The future-history of

The Pentagon War


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The Human-Centauri sun

Found in constellation: Hydra
Catalog names: [formerly] Haberd's Brown Dwarf 629
Right Ascention, Declination, and Distance: 8h47m, -6°45', 6.80 light-years
Galactic (X,Y,Z) coordinates in ly: -4.50, -3.90, 3.30 (almost directly between CN Leonis and Sirius)
Velocity vector in A.U.s/yr: 2.3, 0.6, -0.8
Light-Years to neighbors: Wolf 359 4.4, Sirius 4.5, Procyon 5.6, Lalande 21185 5.7, Bonner Durchmusterung +5°1668 6.7, Sol 6.8, Alpha Centauri 7.6, Ross 128 7.7, Ross 614 8.8, Kapteyn's Star 11.0, AD Leonis 11.1, Epsilon Eridani 11.4, Barnard's Star 11.8, FL Virginis 11.9, UV Ceti 12.2, CC 658 13.6, Groombridge 1618 13.8, Omicron-2 Eridani 14.5, WX Ursa Majoris 15.0, Ross 154 15.85
Arity: singular
Spectral class: M6
Luminosity class: V
Visual luminosity: 0.00002 x Sol
Bolometric luminosity: 0.0002 x Sol
Mass: 0.07 x Sol
Diameter: 0.12 x Sol
Age: At the start of the War, 139 years.
Heavy element abundance: 130% of Sol
Comfort Zone (visual): 0.0045 AU (670 000 km)
Orbital period in Visual CZ: 0.42 days (10 hours)
Comfort Zone (bolometric): 0.014 AU (2 120 000 km)
Orbital period in bolometric CZ: 2.3 days
Angular size of star in sky in bolometric CZ: 4.5° (about 9x Sol)

Future history of the Pentagon War universe:

(A number at the beginning of a paragraph indicates mean Solar [Earth] year, with year 1 being arbitrarily set as the year of first contact between humans and Centaurians.  Humans still use the Gregorian calendar year; Centaurians use their own calendar except when communicating with humans.  For reference, the year "x" is sometimes called "x AC", with AC being variously interpreted as "Alpha Centauri", "After Centaurians", or "Anno Contacti".)

-43 – Manned (or should I say Centaurianned) survey of Alpha Centauri B performed by the Centaurians.  The second planet from the star is found to harbor life; however, nothing more advanced than a trilobite-like species has evolved.

-38 – First colonists sent to Alpha Centauri B II.  The oxygen atmosphere means there is no need for terraforming — er, A-III-forming.  However, all native life is completely inedible, so imported grains have to be planted.  These eventually get out into the wild and begin displacing the native autotrophs.  A mass extinction of native life begins; the colonists must study the ecosystem rapidly before it is so disrupted as to be nothing like what it once was.

-35 – Centaurians lay plans for a spacecraft using what humans would call the Bussard interstellar-hydrogen-collection principle.  They have not yet overcome the ramscoop drag problem, so this spacecraft's top speed is limited to its own exhaust velocity.  It is to be sent to Alpha Centauri Proxima.

-30 – First Centaurian ramscoop completed and sent on its mission to Proxima.  In the years that follow, new designs emerge that could make the trip considerably faster, but the Centaurians figure, hey, we can wait, it's only Proxima Centauri.  Their attitude turns out to be completely correct.

-15 – Details of the bleak, lifeless rendezvous with Proxima Centauri reach Alpha Centauri A III.  These results aren't too surprising, seeing how ol' Alpha Centauri C is a flare star.  Centaurians realize they're going to have to literally reach for the stars if they want any hope of contacting another intelligent species.  Several decades ago, the Sol system nearly doubled its total radio energy output; some Centaurian astronomers have interpreted this as a sign of emerging technological life in that system.

-9 – Centaurians complete their first true starship, a proton-fusion-powered Bussard-like Scramjet, which can fuse collected hydrogen in a lengthy QC&C reactor that doesn't slow the incoming materal down.  A vast interstellar plasma deflection field makes up the majority of the craft's "scoop", and is tuned to create drag during the deceleration phase (as well as collect some hydrogen to replenish the fuel tanks).  This spacecraft does have to carry some fuel for the "boost" phase (it can't gather a lot of interstellar medium below about 10% of c or so), giving it a modest 3-to-1 fuel-to-empty-mass ratio.  They put a crew aboard it and accelerate it at a steady 0.8 g toward their nearest Truly Interstellar neighbor, Sol.

1 – Arbitrary [Earth] year some time in the 21st century.  First contact with Alpha Centauri is made.  We detect their starship on its way to the inner Solar system, it enters a direct circular orbit about the Earth at an altitude between the two Van Allen belts, everybody gets jumpy, and then some paranoid general orders two ground-lanched tactical nuclear missiles (which were originally ICBMs for use against strategic thermonuclear launchers) to attack the starship as their target.  The Centaurian spacecraft is blown to pieces in a fission fireball.  (The Centaurians had never encountered nuclear weapons before, and weren't expecting to get shot at anyway.  The only other place they'd found life had been Alpha Centauri B II.)  The U.S. government, which had been working toward being the World Federal Government anyway, kind of takes over and launches a massive defense program, and redesignates its Air Force as its Space Force, to prepare for the inevitable Alpha-Centaurian counterattack.

2 – Analysis of the fragments from the destroyed Centaurian spacecraft show that it was almost certainly a Bussard-Ramscoop-like design.  It also seemed to be able to force ordinary light-hydrogen (protium) to undergo controlled, sustained fusion.  Although the engine assembly is in nowhere near one piece, the QC&C core is more-or-less intact.  The painstaking process of reverse-engineering QC&C technology begins.  This helps to further prepare for the inevitable Alpha-Centaurian counterattack.

3 – World Federal Government formed.  In some ways it's less oppresive than the previous national governments it supplants; in other ways, it's more oppressive.  In less than two decades, though, this won't really matter.

15 – The inevitable Alpha-Centaurian counterattack.  Some of the paranoids heading up the Alpha Centauri government perceived Sol as a potential threat to their own home soil, reasoning that any species that could vaporize one of their spacecraft in one stroke must also be at least that much farther ahead of them in interstellar travel capabilities.  (We're not, they're just afraid we are.)  Ten combat-oriented interstellar spacecraft (all proton-fusion scramjets) enter low Earth orbit, looking for missile launch sites to shoot down.  Nuclear missiles converge on them both from ground launch sites and newly-installed orbital launchers, but this time the Centaurians manage to shoot them down before they hit their spacecraft.  Well, most of them, anyway — a few get through and destroy seven of the ten Centaurian craft while crippling another.  The crippled starship has to be abandoned in orbit.  Big fighting ensues.  Ground sites where missiles and suspected missiles are stored are attacked by the Centaurians from orbit.  Troops at these sites, of course, die.  After a few [Earth] days, the fighting reaches an uneasy cessation, and the Centaurians send down an illustrated dictionary and analog LP-like recordings of their language.  The World Federal (formerly U.S.) Government responds by sending them an illustrated English dictionary and some digital optical discs (mostly to boast about the level of our technology).  Although their language is unpronounceable to a human vocal mechanism (while our discs are, at the time, beyond their ability to read), communications are established, diplomats meet behind hermetically-sealed windows, and the Centaurians and Humans agree to an uneasy ceasefire — which, of course, leads to a cold war by both sides.  Having seen the real state of our space capabilities, the Alpha-Centaurians no longer consider humankind to be as much of a threat as previously supposed.  Captured human satellites provide the Alpha-Centaurians with a computer technology the likes of which they have never seen before.  Conversely, the one abandoned Centaurian craft was in good enough shape that humans were able to figure out the final secrets of its QC&C proton-fusion scramjet engine; this marks the beginning of the end of the Ballistic Age of Space Exploration.

16 – First QC&C proton-fusion electric power plant begins operation.  It's a single-stage proton-proton reactor, originally designed to address the burgeoning market for deuterium and sell its electric output as a by-product.  As the supply of deuterium skyrockets, however, the reactor quickly shifts its business focus to the power generation market.  The process is so cheap and efficient that within two decades, no other kind of large scale power plant (other than the hydroelectric dam) is in use anywhere on Earth.  The Age of Cheap Energy begins.  With deuterium now available in such great abundance, both protium-deuterium hot fusion and QC&C deuterium fusion allow humans to really pick up the pace of space exploration and exploitation.  Humanity had already gotten its act together with every aspect of spaceflight except launch costs; now, boosting people and cargo into or past Earth orbit is no longer a big deal, and orbiting spacecraft construction facilities spring up practically overnight.  Human colonies on Earth's moon follow almost immediately.

19 – Alpha Centauri learns of the shaky armistice reached on Sol's third planet and decide they need to develop an antimatter arsenal.  Positron collectors and starlight-powered antiproton factories are set up on Proxima Centauri's first solid planet.  (Proxima's flare activity means its planetary system must remain uninhabited, which makes it ideal for dangerous operations such as antimatter manufacture.)  [Note: at this point in history, antiprotons are considered the most useful form of antimatter, since they are 2000 times heavier than positrons and, thus, more grams can be herded into magnetic bottles more easily.  Positron collecting is only of fringe interest to any star system's military.]

20 – Martian colony follows soon after the lunar one, and terraforming begins (in the form of planting lots of dark-colored plants wherever there might be water).  Humans begin colonization of the larger asteroids and the Galilean moons.  The World Federal Government that started these colonies makes many overtures about freedom and self-sufficiency, but still considers them subject to World Federal Government control; however, this policy has yet to be tested.

21 – North Mars colonized.

22 – Colonel Ira Henderson makes his address to the Earth Committee for Space Travel.  Of the nearby star systems, Sirius, Lalande 21185, and V1216 Sagittarii (alias Ross 154) are at the top of the list of candidates for colonization.

23 – Mars and North Mars colonies grow to each others' borders.

24 – The Mars/North Mars conflict.  After months of bloody fighting, Earth intercedes by taking strict control of both of them.  (At an average opposition, a 1g brachistochrone flight from Earth to Mars would take about 2 days.  At an average conjunction, it would take four-and-a-half days.)  This marks the solid beginning of the transition from the World Federal Government to the Solar Federal Government.

27 – Alpha-Centaurian "check up" starship arrives in Sol space and reports current state of events to Alpha Centauri.  The starship's personnel consist of one very large Centaurian clan.  Some of the visiting Centaurians decide to stay in North Mars, forming their own split-off clan (and coining their new clan's name on the spot.)  The World/Solar Federal Government's constabulary in North Mars allows it.  They're greeted with open arms; but as soon as the starship leaves, their human hosts order them into confinement under armed threat.  One of the Centaurians, when told the implement being pointed at them is a deadly weapon, shrieks and charges at the gunman, who shoots and kills the Centaurian.  The rest are rounded up, quarantined, and studied intently (two of them with microscopes and scalpels) — but not before some of each species' xenobacteria are exchanged.  The way in which the Federal Government lured these Centaurians into their clutches is to blame for the lack of epidemiological precautions.  While on its way out of the Solar system, the check-up spacecraft surreptitiously leaves some hard-to-detect reconnaisance satellites between the orbits of Uranus and Neptune.  Our progress disturbs them.  When the humans find one of these satellites, they too are disturbed by this interstellar spy and figure the best course of action is to branch out outside of our own star system.  The SBI is formed, and the first plans for the colonization of Sirius are begun.

28 – One of the many strains of airborne Alpha-Centaurian bacteria to be brought to North Mars causes a lethal epidemic there.  Over a quarter of the human population in North Mars dies before the disease is contained and an anti-xeno-biotic is developed.  Conversely, plain old harmless-to-humans E. coli kill each and every one of the quarantined Centaurians, since the visiting Centaurians had no natural resistance and weren't equipped to handle a plague.  Before all the captive Centaurians die, though, the clan's medical expert provides crucial assistance to their human captors, helping them to ultimately find a cure.

30 – Bussard scramjet starships, though much smaller than the designs the Alpha-Centaurians visited us in, leave Sol for Sirius en masse.  And not all Federally backed, either.  Several rag-tag groups of people that can't stand the Federal government take off to Brave the Wilds themselves.  As do some criminals, much like the indentured servants that came to America in the 17th and 18th centuries.  The Federally-backed starships carry a small army of assembly robots that can mine and smelt the native ores, build QC&C generators, construct housing, raise food crops, etc..  However, as it turns out, these robots can also be programmed to assemble military hardware as well.  Since each scramjet can only carry a couple dozen people tops, they also carry along an ample supply of frozen embryos, and each of the women must agree before departure to implant pairs of these frozen embryos in her uterus, and thus bear twins, over-and-over again for the rest of her healthy adult life once they reach their destination.  This is the only way the colony can reach a stable population size in a short time, and raise these children in families large enough to rival a full school classroom.  Nearly all the colonists are women; due to their constant pregnancy and the demands of child rearing, assembly 'bots are expected to be the primary labor force.  [Note that at this time, hibernation technology has not yet been discovered by humans.  These colonists have a long ride ahead of them.]

32 – A second wave of small starships, all Federally backed, depart Sol for Sirius.

34 – Via their outer-Sol-system-orbiting satellites, the Alpha-Centaurians learn of our colonization fleet and send a small fleet of their own to Sirius.  They also like our idea of colonizing a new star system and, fearing Sirius might be used as a second staging area for human military assaults, send out a slightly larger colonization fleet to CN Leonis (alias Wolf 359), consisting mostly of malcontents.  (V1216 Sagittarii, while closer, larger, and with less frequent flare activity, has bigger flares when they do occur; plus, it has a lower abundance of heavy elements, making its resources both scarcer and harder to exploit.  UV Ceti has so much flare activity as to be uninhabitable.)

36 – By this time, all the cheap energy created by QC&C fusion on Earth has ushered in a worldwide post-scarcity economy.  Government oppression is no longer an issue, since starvation (or even the threat of starvation), which drives the kind of strife that prompts most government intervention, has become a thing of the past.  Poverty, in the sense of some being wealthier than others, still exists, but a "poor" person in this world never has to worry about life's necessities.

39 – The fledgling SBI reports the outbound Centaurian starships to the Solar Federal government on Earth.  Two spacecraft were positively identified as being aimed for CN Leonis; the rest could not be pinned down as to their destinations.  Sol assumes the entire Centaurian fleet is headed there.

40 – Sol: Several armed starships are sent to CN Leonis.

42 – Sirius: First human interstellar scramjets arrive at Sirius A.  The fourth planet from the star lies closer than the traditional Comfort Zone, yet, because of the extremely low CO2 content of its atmosphere, has pre-aerobic life on it at the middle-to-high latitudes.  Colonies are established and terraforming slowly begins, with an eye on keeping CO2 levels down.  The population of this new colony is frighteningly low — you can only make an interstellar scramjet so heavy before you reach the upper limit of how wide your scoop field can be — but thankfully they brought along robotic assemblers to help build their infrastructure.  Eight-and-a-half light-years worth of distance from their original home makes the three months of travelling time between England and colonial America look like a trip around the block.

44 – Second wave of starships arrive at Sirius.  These more gung-ho Solar Federalists quickly learn just how much On Their Own they really are.  It doesn't take long for Sirius to declare its independence.

47 – First Alpha-Centaurian scramjets arrive at CN Leonis.  Colonization of CN Leonis II begins.  Since CN Leonis is a mild flare star, CN Leonis II can never be terraformed (at least on its surface), but this means its surface is ideal for setting up the antimatter production facilities that nobody wants in their back yard.  A period of "salutory" neglect follows, during which the colonists engage in a massive military buildup.

50 – First Alpha-Centaurians arrive at Sirius.  First thought to be another wave of human colonists, the Sirians transmit the news of their independence to them.  When they discover that they aren't human at all but Alpha-Centaurian, panic ensues, and the entire Sirian military is mobilized against the starships.  (A few of the scramjets the humans had made their journeys in have been converted to weapons platforms, in anticipation of attempts by Sol to re-take the system.)  Being primarily colony spacecraft and not expecting this kind of resistance, the visiting Centaurians soon surrender.  The secrets of the Alpha-Centaurian interstellar plasma deflection fields, used in these colony craft, are unlocked by humans for the first time; they are more efficient than the methods humans used for surviving relativistic speeds.  Since the starships' occupants are still alive and can be questioned, the Sirians discover that certain cooling rooms on board — which had been glossed over by analysts back on Sol when examining the damaged Centaurian starship after Second Contact — are actually hibernation chambers.  Being cold-blooded, Centaurians will hibernate whenever the temperature falls below 5° Celsius, during which time they consume practically no food or water and little oxygen, and age at about 1/5 the normal rate.  When Sirius broadcasts this discovery back to Sol, human hibernation technology — once considered "too risky" — is unshelved and given center stage, lest Sol suffers a "hibernation gap."

51 – CN Leonis: News of Sirius's declaration of independence arrives.  And so does Sol's military force, with gun ports open.  The Solar folks weren't expecting the massive military buildup that had happened in the past five years, and the Leonians blast hell out of some Solar spacecraft while capturing the rest.  The prisoners (all of whom are human) are paraded around on CN Leonis-II like captured slaves.  News of this little replay of the Bay of Pigs invasion has been sent back to Sol before Sol's forces are completely vanquished, though.

52 – Sol: News of Sirius's declaration of independence arrives at Sol.  Sentiment among interplanetary colonists there, and even on Earth, is mixed, so the Federal government can only send a small military force to Sirius to restore order there without losing face.  That military force consists of one interstellar craft carrying four automated "fighter" spacecraft which had originally been engineered to fight the Alpha-Centaurians.

59 – Sol hears about the victory at CN Leonis and decides to leave the damn place alone — in part due to a small, grass-roots group of "learned" citizens calling themselves Humans for Better Interspecies Relations.

60 – Alpha Centauri hears about the victory at CN Leonis, but only by indirectly inferring it from the least official of their communications.  They're not sure who to be infuriated at more: Sol for attacking their colony, or CN Leonis for not acting like they were an Alpha-Centaurian colony any more.  Not knowing how strong CN Leonis is, Alpha Centauri sends its own military force there to prevent them from "breaking off" the way Sirius did from Sol.  Some concerned citizens become worried by all this warmongering and begin stepping up personal correspondences with Solar citizens in an attempt to bridge the species gap.

62 – "Peace Keeping" force from Sol arrives at Sirius.  The Sirians, who had been expecting such a turn of events, had converted some of the scramscoops they made their journeys in into weapons-carrying spacecraft.  Although outmatched in terms of maneuverability by the fighters, the extra armor plating and Alpha-Centaurian interstellar plasma deflection fields (now beefed up to "battle screens") are all the edge the Sirians need.  They win the Sirian War for Independence in a matter of days.

65 – New slew of messages from the more concerned citizens of Alpha Centauri reaches Sol.  The Humans for Better Interspecies Relations grows as a result.

66 – The Humans for Better Interspecies Relations cause a minor backlash movement among some old-timers, resulting in the most hawkish election turnout in twenty years.

70 – News of the outcome of Sirius's War of Secession reaches Sol.  The Solar Federal government grudgingly accedes to Sirian independence; it works to the advantage of the hawks, who can now point to Sirius as a "new outside threat" to further Sol's cold-war footing.  The Humans for Better Interspecies Relations are now the best place to go if you want to correspond with a Centaurian in another star system.

71 – The Humans for Better Interspecies Relations reaches a critical mass.  Citing emotional-plague behavior and so-called "intolerance" as the main cause of xenophobia, they announce the intention of building a new, independent colony in a new star system, and send an open invitation to any other humans or Centaurians who wish to join them.  The only restriction on citizenship in this new "Human-Centauri", they insist, is that emotional plague behavior will not be tolerated, and that they will be free to deport any emotional plague characters.

72 – Alpha Centauri's military force arrives at CN Leonis.  The fleet is devastated within minutes of announcing their role as enforcers.  Leonian independance has been waiting to happen, and this provides all the impetus it needs.

75 – News of the Human-Centauri project reaches Alpha Centauri.  There is a large degree of interest — and some suspicion from the Alpha-Centaurian government.  The interested Alpha-Centaurian citizens realize that the best solution to avoid interference from any of the three existing governments is for Human-Centauri to be in a star system that nobody else is interested in.

78 – News of the Human-Centauri project reaches CN Leonis.  No Leonian with interstellar travel capability is interested.

79 – Sirius: News of the Human-Centauri project arrives.  Few Sirians are interested.  Sol: Agreeing with the interested Alpha-Centaurian citizens, the Humans for Better Interspecies Relations have already chosen one of the least interesting Human-Centauri locales imaginable: a substellar ball of heavy-element-rich hydrogen named Haberd's Brown Dwarf 629.  It didn't even manage to ignite into a star under its own weight, but is large enough to be ignited artificially.  (It's also situated closer to Sirius and CN Leonis than to either Sol or Alpha Centauri.)  The brown dwarf also never underwent a planetary formation period, and is instead surrounded by a densely-packed ring of orbiting debris.  The first wave of emigrants leaves for this newly-christened Human-Centauri system, carrying with them an antiproton bomb which they figure will start a fusion reaction within the substar.

79 – News of CN Leonis's sovereignty arrives at Sol.

80 – Sirius: News of CN Leonis's sovereignty arrives.  (The Leonians have enough of a resource base to feel comfortable in broadcasting this fact, unlike Sirius.)  Alpha Centauri: News of CN Leonis's independence arrives.  This causes Alpha-Centaurian government to fear it's losing control and clamp down on its own populace somewhat.  The Human-Centauri enthusiasts get even more antsy to leave.

83 – Alpha-Centauri: News of the location of Human-Centauri arrives.  A few Centaurians back away out of skepticism over the ability to "create" a star — not to mention the insane logistics of living in an asteroid field that puts Sol's asteroid belt to shame — but in light of the more militaristic political situation in their home system, most of the previously interested citizens embark for this new frontier.  With enough supplies to get back home if stellar ignition fails, of course.

88 – First Solar immigrants arrive at Haberd's Brown Dwarf 629 and prepare to convert it into a star system.  The debris ring orbiting the brown dwarf turns out to be thickest right at the distance from the future star that they wanted to build their civilization, meaning any "worlds" they might have planned on building would be right in the middle of an asteroid freeway.  While stellar ignition preparation continues, the homesteaders decide to turn the disadvantage of this debris ring into an advantage.  They build their new homes right into one of the biggest asteroids itself.  They have to live in pressurized dugouts with almost no gravity, but lacking gravity has its advantages too.

89 – First emotional plague behavior incident at the future site of Human-Centauri.  The perpetrator is given a choice of one year's private confinement, or deportation back to Sol.  She leaves.  Many feel the situation was not handled well and that new standards for dealing with plague-characters should be adopted.

90 – Human-Centauri stellar ignition.  A star is born.  Asteroid scaffolding construction crews can now work by the light of this new candle, instead of their portable fusion furnaces.

93 – First Centaurian immigrants arrive on (Gregorian) June 5th to a warm welcome at the still-under-construction Human-Centauri habitat ring.  The human inhabitants of Human-Centauri officially name June 5th "Grand Opening Day".  Sadly, a few Centaurian's are found to have character structures tainted with their own species' version of the emotional plague, and have to be sent back.

94 – Sirius: Light from the newly-ignited star arrives.  Sirians are flabberghasted that these independent malcontents could actually pull it off.  CN Leonis: First light from Human-Centauri arrives.  The Leonians are frankly amazed, but have had political and economic problems of their own so can't pay it much attention at this point.

95 – Construction on the first Human-Centauri major asteroid has progressed to the point where the Citizens start eyeing the second.  The asteroid is officially christened Human-Centauri I, but among the inhabitants it's simply known as "The Capital.".  1.0 g centrifuges start springing up in the more densely-human-populated areas, as places to keep the human occupants from suffering muscle and bone mass degeneration.

97 – First light from Human-Centauri reaches Sol.

98 – First light from Human-Centauri reaches Alpha Centauri.

100 – First disgruntled Human-Centauri reject arrives back at Sol.  Her story blurts "Human-Centauri unfair!" in tabloid-like news media across the system.  Those who've actually met her tend to agree with the Human-Centaurians' decision, however.

101 – Second major Human-Centauri asteroid now inhabited with its own underground centrifuges; due to the influx of new waves of immigrants, Human-Centauri II is now christened "New Mars".  Another lange asteroid is commendiered as a "greeting area" where prospective Human-Centauri citizens, emotional plague bearing or not, may arrive and live before being accepted or rejected.

107 – Human-Centauri III asteroid now home to underground centrifuges too.

113 – Human-Centaurian projections indicate that their population may exceed the capacity of all three major asteroids within the century.  Plans are laid for a "higher class" neighborhood, consisting of the future Human-Centauri IV and V, the two largest asteroids in the star system.  (Human-Centauri I was chosen not for its size, but for the usefulness of the ice and carbonaceous materials near its surface.)

124 – Human-Centauri IV added to the artificial star system's usable real estate.  Its inhabitants name it "New France."  It is considerably larger than any of the first three asteroids.

143 – Human-Centauri V inhabited.  Human-Centauri VI is not planned for the near future.

150 – Mad Scientist's phased antimatter bomb experiment approved by the Solar Federal government's Board of Research.  He is granted Luyten 726-8 B IV for his personal testbed; the extreme flare nature of UV Ceti makes the system too hostile for habitation.  Mad Scientist departs Sol system for good old UV Ceti.  Pre-assembled materials for the Phased Antimatter device follow soon thereafter.

151 – SBI issues Arnold Hassleberg NK438CH5, a top-of-the-line Bussard fusion scramjet, which has external inflatable fuel tanks that allow it to reach a much higher ramscoop speed before burnout, and which is built to sustain a continuous 2g of acceleration or deceleration.

152 – SBI agents Arnold Hasselberg and Jerry Redlands depart Sol for UV Ceti.

161 – Mad Scientist arrives at UV Ceti IV and begins setting up shop.

162 – Start of the story.  Mad Scientist test-detonates first Phased Antimatter device on UV Ceti IV, destroying the planet (and himself).  SBI observers Arnold Hasselberg and Jerry Redlands discover double-sided hole in space (filled with utter darkness) at the flashpoint.  Arnold accidentally falls into hyper hole and is believed gone forever.  Jerry violates orders and sends the secrets of the terrible, planet-rending destructive power of the Phased Antimatter Bomb to all five star systems.

177 – Jerry's data-transmission signal reaches all five systems simultaneously.  The problem of What Happened At The Flashpoint becomes the hot topic in the various scientific communities. Sirius's physicists quickly stumble upon the answer to the riddle of the Phased Antimatter Bomb by codifying the Energy Density Limit.  The news is sent to the other four star systems.  Since the realization involves the fact that the Phased Antimatter Bomb essentially produced a four-dimensional stairstep into a parallel 3-D space, the bomb is re-christened the "Hyper Bomb".

186 – News of Sirius's discovery reaches Sol and Alpha-Centauri.  Sol had gotten pretty close to this answer themselves, but Sirius still beat them to the punch.  Alpha Centauri has a large enough positron stockpile to attempt building a hyper hole tunnel between themselves and another star system.  Since trade with Sol would be the most profitable to them, and since Sol also has the largest positron stockpile of all five systems, Alpha Centauri sends a message to Sol detailing how the two of them could build a hyperlink.

190 – Alpha Centauri's hyperlink idea reaches Sol.  The Solar Federal government had a similar idea a couple of years ago, and they're ecstatic to try it.  They send the go-ahead signal to Alpha Centauri.  They even send precise aiming and timing information to Alpha Centauri as to when (5 years hence) and where (between the orbits of Jupiter and Saturn) they're going to blow their hyper bomb.  They figure that even if Alpha Centauri doesn't agree, or misses their target, or the theory doesn't work, they'll get to put the hyper bomb through a real domestic test.

194 – Sol's acceptance and plans reach Alpha Centauri.  The A-III government finishes its own hyper bomb and starts lining it up to within a thousandth of an arc-second of the precise location Sol said they'd be detonating theirs.

195 – Both Sol's and Alpha Centauri's hyper bombs go off.  The aiming and timing were superb on both ends.  Despite the monumental odds against them, the hyper link was successfully created.  (One photographer poised behind the Sol bomb was killed, though, since no one had anticipated the foreflash from the other guy's hyper bomb would come though the hole to their own side.)  The English-language radio transmission of "Can you hear us?" was greeted with an English "yes!" from the other end almost immediately.  Less than a week later, the first manned (Centaurianned?) Alpha-Centaurian spacecraft crosses the hole to Sol space, and the next day, Sol's first passenger craft voyages to Alpha Centauri in a like manner.  Sol and Alpha Centauri immediately relay plans for similar hyper holes to Sirius and CN Leonis, respectively.

196 – Analysis of the blast and hyper holes indicates that there was more of a margin for error on angular alignment than had been anticipated (which was why the first dual detonation had been successful).  Sol and Alpha Centauri each place a communications relay station in matching orbit with its end of the Sol/Alpha-Centauri hyper link.

197 – Border patrol functions are added to the communications relay stations, first by Sol and then by Alpha-Centauri within the same year.

198 – To ensure the border patrol stations stay put, Sol and Alpha Centauri each move an asteroid a few miles in diameter into hyper hole orbit, and anchor their station to it.

201 – Sol's good news arrives at Sirius.  They suspect a trick, but have been looking for an excuse to test their own hyper bomb.  Like Sol before them, they transmit intended coordinates and timing back to the system that suggested it to them.

203 – News of the Sol/Alpha Centauri hyper hole arrives at CN Leonis.  Although it would deplete them of almost every positron they've cultivated (they'd been stockpiling primarily antiprotons prior to the success of the Phased Antimater Bomb), CN Leonis agrees to detonate their own hyper bomb and transmits the intended time and position to Alpha Centauri.

208 – The Sol/Sirius hyper hole detonations work.  Communications relays are set up on either side of the hole immediately.  Sirius begins its second hyper bomb and asks its other neighbor, Human-Centauri, if they'd like to link with them.

212 – The Alpha Centauri/CN Leonis hyper hole detonations are a success.  Now Human-Centauri is the only one of the five major star systems to be lightspeed-isolated.  CN Leonis tells of this success to Human-Centauri, and accelerates its positron collecting operations in an effort to build another hyper bomb as soon as possible.  (Not just for linking with Human-Centauri, either; the Leonians, who are primarily Centaurian, are wary of their species' homeworld.  A planet-killer bomb would make quite a deterrent.)

213 – Sirius's request to establish a hyper bomb link with Human-Centauri reaches Human-Centauri.  Positron collecting has been slow at best, but they figure they'll have enough in three or four years to make an attempt.  The details of where and when they intend to detonate are transmitted to Sirius; since four years is only enough time for a one-way message between these two worlds, Sirius will not have the option to ask them not to make the attempt if they so choose.

215 – A Leonian "Would you like to establish a hyper hole link with us?" request arrives at Human-Centauri.  They agree, but tell them it'll take some time to accumulate the necessary positrons since they're already planning to link with Sirius.

217 – Human-Centauri's "We're going to detonate" message arrives at Sirius, who obliges them.  The two systems successfully establish a hyperlink and use the new trade route to request some extra positrons for their proposed link with CN Leonis.  Sirius refuses.  Human-Centauri begins the ten-year process of positron accumulation to produce the necessary 250 kg of positronic antimatter for a hyper bomb.

218 – By using the four existing hyperlinks, the Leonians actually deliver 20 kg of their own positrons to Human-Centauri.  They are really intent on having a direct Human-Centauri link.  The Human-Centauri Defense Force gets a bit suspicious about this, but the go-ahead for the next link detonation is given to the Leonian courier, who takes it back to CN Leonis.

219 – Human-Centauri completes its second hyper bomb.  The communications relays on all the existing hyper holes greatly facilitate the process of synchronizing their detonation with CN Leonis's.  Creation of the fifth hyper hole link is a success.

220 – The formerly small inhabited region on Human-Centauri's "greeting area" asteroid expands into a tourist spot, as it is the only place in the Human-Centauri system that noncitizens can go.  An embassy is established there.

223 – Sirius completes another hyper bomb.  They do not use it to create a hyper link with Sol or CN Leonis, and have no intention of doing so.  For the first time in the history of post-first-contact space, a star system holds the threat of planetary annihilation over its neighbors.

224 – Alpha-Centaurian intelligence discovers that CN Leonis has had their own spare hyper bomb for at least as long as Sirius has.  An emergency summit of representatives from all five governments is held on Human-Centauri II.  The first SALTY treaty is signed, banning positron stockpiling for any purpose other than creating hyper hole links.  All star systems begin a build-up of conventional antiproton warheads and military spacecraft.

225 – Sirius and CN Leonis refuse to comply.  Sol is discovered to have made two hyper bombs since it coestablished the Sol/Sirius link.  SALTY II, requiring all hyper bombs to be phased out over six years, is proposed and signed by four of the five systems (CN Leonis refuses), and, since unanimous participation was needed, is rejected.  SALTY III, a more palatable solution allowing each star system to stockpile at most one hyper bomb at a time, is signed unanimously.  The border-patrol installations on both sides of each hyper hole link are beefed up into massive "gate guards" capable of holding their own against an entire carrier's complement of fighters.

226 – Sol refuses to dismantle or use its second hyper bomb, giving excuses like "Well, what if a new alien species showed up and decided to attack us?".  SALTY III breaks down.  Sol proposes SALTY IV, which, after cutting through pages of legalese, basically says that everybody else gets to keep one hyper bomb in reserve, but Sol gets to keep two.  No other star system signs this treaty.  Tensions mount.  To avoid threats of blockade, Sol reluctantly signs SALTY V, forcing them to dismantle their second hyper bomb but (in a loophole their diplomats discovered) allowing them to stockpile as many raw positrons as they liked.

227 – Discovering the SALTY V loophole, the other star systems demand another summit with Sol.  This one is held on Alpha Centauri A-III.  After heated discussion and the threat of war, SALTY VI is ratified, which does not limit the size of a positron or hyper bomb arsenal but requires that each star system keep all of its positrons (and hyper bombs) in plain sight for the other systems to inventory.

228 – SALTY VI seems to be working.  With the exception of Human-Centauri, which has only one hyper bomb in reserve, all 5 star systems have two hyper bombs and some extra positrons on the way to building a third bomb.

229 – Alpha Centauri discovers a third Solar hyper bomb that they've been keeping hidden.  Sol's transit privileges through Alpha-Centaurian space are revoked.  Yet another conference is held, this time on Human-Centauri II.  While James Carter (Sol's representative) is en route to the conference through Sirian space, he receives an encrypted message from the SBI telling him that that a secret extra Alpha-Centaurian hyper bomb has just been discovered.  At the conference, Sirius, CN Leonis, and even Human-Centauri are strongly suspected of having an extra hyper bomb (or in the Leonians' case, two) in reserve that they weren't telling the others about.  Blockade decisions fly around the room.  Tempers flare, tolerance limits break.  Finally, Alpha Centauri's representative (Holsteader) declares war on CN Leonis.  And James Carter declares war on Alpha Centauri.  And Holsteader declares war on Sirius.  And CN Leonis's representative (Krammer) declares war on Human-Centauri.  And Sirius's representative (Håkan Brezhnev; at one point I thought of naming him Ivan Harlbjorg) declares war on Sol.  And on it goes, until every star system is formally at war with every other star system.
   Realizing the strategic threat of two hostile neigbors, Sol decides to make a quick strike against their weaker neighbor so that they can focus on their more powerful foe.  They don't have the fighter carriers to commit to a full-scale military win against Sirius, so they opt instead to smash the bulk of the Sirian transmute-tanker fleet.  This hugely limits Sirian fuel supplies for over a year.

230 – A year into the war, Torra Zorra, Ken Tractor, and Jennifer Doe receive The Message.  They request a starship — something for which little or no use has existed for over a decade — to make the voyage to UV Ceti IV's remains.  Yukariah Heap agrees.  The Message indicates that they had better get there inside of 10 years; unfortunately, UV Ceti is over 13 years away from Human-Centauri.  Only the Sol system is close enough to UV Ceti to cut a non-hyper-hole interstellar voyage down to less than 10 years of travel time.  Taking a prototype interstellar warship built for hypothetical colonizing missions (yet small enough to fit through a hyper hole), they run a deadly gauntlet across Sirian space and past three hostile gate guards into Sol space, and take off for UV Ceti.  Thankfully, Sol does not pursue, since the three are not maneuvering toward any potential targets and the Solar military has its hands full with Sirius at that moment anyway.
   A quick relativistic calculation shows that a continuous 1g acceleration will not be enough to cross the 8.554 light-years from Sol to UV Ceti in 10 years' time, but a continuous 2g acceleration will.  At 2g, it will take 4.734 years of rest-time [1.442 years "proper time"] to reach the half-way point, at which point they will be travelling at 0.99479 of c (at which speed γ = 9.812).  If you can sustain 2g, though, you don't have to accelerate all the way to the half way point.  You'll reach 0.95c in 1.446 years rest time, at which point you can coast for 6.798 years, then decelerate at 2g for another 1.446 years — total travel time: 9.69 years.  If you accelerate to only 0.92c (γ = 2.72), it'll take you 1.116 years of rest time to get going that fast, duing which you'll cover 0.738 light-years; you'll coast for 7.08 ly at 0.92c, which'll take 7.69 years of rest time, for a total trip time of 9.925 years.

236 – Sirius drops antimatter bombs on several major Human-Centaurian metropolitan areas, including New France and New Mars.

237 – The war is going badly for Human-Centauri.  Although CN Leonis has been leaving them alone, Sirius has been dealing them heavy blows.  They need help.  They give CN Leonis permission to transit their space to put pressure on Sirius, since CN Leonis is at war with Sirius too.  The Leonians say they'll need to operate from the Human-Centauri habitat ring if Human-Centauri is going to get their help.  In one of its most self-destructive long-term moves ever, Human-Centauri grudgingly allows the Leonian military — including its Fanatic Brigade — to inhabit Human-Centauri citizen territory.  The emotional plague poisoning begins.

238 – Throwing off the gloves, CN Leonis authorizes its Fanatic Brigade to use a Leonian hyper bomb on Alpha Centauri A III.  They succeed, and Alpha Centauri A III is half-shattered.  The homeworld of all Centaurians is reduced to a floating hulk.  So much for the history, art, archaeology, biology, paleontology, geology, etc., etc., of the planet.  Thoroughly appalled, Human-Centauri revokes its permission for CN Leonis personnel to inhabit citizen areas and begins to round them up and herd them out, but the social damage has already been done.

240 – The Chosen Three arrive at UV Ceti.  No news has been beamed to them, since the signals would've had to have originated from Sol.  The Messages are found to be from the "ghost" of Arnold Hasselberg, who points out the Zero Drive that the Mad Scientist had developed before he shattered the fourth planet.  Ken recovers it, Jennifer tries to kill him, Torra Zorra (in attempting to subdue her) accidentally kills her.  They install and test the Zero Drive, then use it to enter a Limbo (neither wholly in Real nor in Parallel space) while moving through the hyper hole.  (This is done by calculating the movement of the hype hole through absolute space as it orbits UV Ceti, and letting it envelop them while their zero-drive makes them stand rock-still.)  On the trip back, they learn the news of the Sirian bombings of Human-Centauri's habitat ring, Human-Centauri's allowance of the CN Leonis military into its citizen areas, and A-III's annihilation.  They emerge from the Human-Centauri end of the Human-Centauri/Sirius hole and, using the decisive maneuverability the Zero Drive gives them, vanquish a Sirian assault force just moments before they would've hyper-bombed Human-Centauri I.  They tell Human-Centauri about the impending End of the Galaxy, who tells of this catastrophe to the other four star systems, who stop mucking about with fighting each other because, darn it, the galaxy could end at any moment.  Ken Tractor and Torra Zorra then take the Sirian hyper bomb originally intended to blow up their homeworld, go back into Limbo through the CN Leonis hyper hole, race to the center of the galaxy, and (using the hyper bomb) squelch the impending explosion of Sagittarius X in the nick of time.  And everybody lives happily ever after.  (Until I write the sequel, that is.)

The Planets

Alpha Centauri A III:

The Centaurian homeworld, abbreviated A-three in human speech, orbits Alpha Centauri A at a distance of 200 million kilometers, making its "year" last 1½ Earth years.  (If the orbit is exactly 200,000,000 km, assuming Alpha Centauri A's mass is exactly 1.1 solar masses, its orbital period will be 1.46795 Earth years.)  It has only one moon, which is about the size of Phobos, and a sidereal rotation period of 17 hours, 43 minutes (thus one A-III year is around 740 A-III days long).  Its axis of rotation is tilted 20° with respect to its orbit, whose eccentricity is nearly zero.  Its size and density are about the same as Venus, making its surface gravity about 80% that of Earth.  The lower concentrations of heavy metals in the planet means naturally occurring radioactives are rarer, which was one of the reasons the Centaurians didn't develop nuclear fission weapons before they met us.

The revelation after Second Contact, that our alien neighbors hail from a planet orbiting in the habitable zone of Alpha Centauri A, put to rest once and for all the debate over whether a planet that close to Alpha Centauri B's gravitational interference could remain in a stable orbit for more than 250 million years.

Its atmosphere, like Earth's, consists almost entirely of biologically-created oxygen and nitrogen gas, the nitrogen comprising about three-quarters (rather than four-fifths) of the atmospheric partial pressure.  Mean sea level atmospheric pressure is about 0.85 Earth atmospheres.  Geological activity on this planet is far more subdued than it is on Earth, resulting in shallow oceans and great, flat expanses of land.  (The lower heavy-element abundance of the planet in relation to the Earth means that these oceans aren't quite as salty as ours.)  Rocky areas on the land masses can be as flat, hard, and vast as the salt flats found in the North American deserts.  It was for swift crossing of these giant natural parking lots that Centaurian foot-wheels evolved.

Its oceans cover the majority of its surface, but are shallower that Earth's and not as saline.  (The lower salinity is due to the lower abundances of chlorine and sodium thoughout the planet.)  The weather tends to be drier than on Earth, meaning fewer freshwater lakes and rivers and not as much groundwater.  The lower level of radioactive materials, relative to Earth, means that the planet doesn't produce as much interior heat as the Earth does, which means less geological activity.  This, coupled with its lack of a large moon, means less of a difference between the highest points and the lowest points on its surface.  The oceans are shallower, and the mountains aren't as high.  There are more continents than on Earth but each continent is smaller, and the coastlines are a lot more convoluted with long inlets and peninsulae than their terrestrial equivalents, providing local access to salt water from much of the land surface.  In the relatively small amount of inland area that's away from these spiny coasts, the topography is mostly vast flat plains, dotted with a few high upthrusting cliffs here and there.

It should be noted that A-III is the most distant whole planet in orbit around Alpha Centauri A.  Farther out is just a thin asteroid belt, and there are no planets or debris of any kind orbiting A any farther out than that.  This is due to the fact that anything orbiting A or B at a distance of more than 2.9 AUs would be thrown out of the star system due to the perturbations of the other star.  There are, however, a few gas giants orbiting the A-B pair out at distances of a hundred AUs or more, the way Proxima does.

The closest English-pronounceable approximation to the name the Centaurians give their homeworld is "Go'orla."  (The o'o sound is actually two o's pronounced in rapid succession with each of two adjacent mouths.)

Ecosystem: A-III has an ecosystem nearly as rich and varied as that on Earth.  Cellular salinity levels for A-III lifeforms are lower than in cells from Earth, since they evolved in less-salty seas.  No A-III cells are Eukaryotic in the sense of having a self-contained nucleus; however, the double-chromosomes necessary for gamete production are present in all multicellular life forms.  As far as organelles go, there are plastids but no mitochondria (the bacteria that evolved double chromosomes were themselves capable of aerobic respiration, so no "guest" respirators were needed).  Endoplasmic reticula are also present in double-chromosomed cells.

There are some flying insect-like invertebrates but no flying chordates (like birds or bats or pteradactyls).  Historically, there was no age of giant land creatures, so Earth's ancient dinosaurs are of particular fascination to Centaurian paleontologists.

Alpha Centauri B II:

The only other world besides Earth and A-III to harbor multicellular life, B-II orbits Alpha Centauri B at a distance of 150 million kilometers, making its "year" last 1.1 Earth years.  It has no moons, and a sidereal rotation period of only 8 hours.  Its atmosphere is thick with CO2, allowing it to trap more heat from Alpha Centauri B, and distribute it more evenly over the planet's surface, than either Earth or A-III.  This is how the planet is warm enough for liquid oceans of water to exist despite its extreme distance from its sun.  The high carbon dioxide concentration in the atmosphere makes it unfit for human or Centaurian consumption directly, but its biologically-created ozone layer combined with cheap and plentiful CO2 filtration technology allow one to walk (or wheel) around outside comfortably wearing little more than a mouthpiece.  The sky above is awfully dreary, though, what with the continual, hazy, Venus-like cloudcover.

The planet's size is akin to that of Mars, but its density is closer to Venus's or Earth's, giving it a surface gravity of about 50% that of Earth.  Only its greater-than-the-normal-comfort-zone distance from Alpha Centauri B allows the planet to retain such a thick atmosphere despite its low surface gravity.

The surface of the planet is a water world, covered everywhere by one vast planet-wide ocean.  Its lack of a large moon means there is far less variation in terrain altitude than there is on Earth, even with the planet's lower surface gravity.  The planet does exhibit some tectonic activity, however, leading to at least a little bit of terrain variation on the sea floor.  The depth of the planet-wide ocean varies from 2 to 4 kilometers, depending on latitude and longitude.  Due to the lack of land for the ocean waves to break against, hideously tall waves are possible.

Ecosystem: Life on this planet has progressed to about the stage of life in the early Paleozoic era on Earth, since multicellular organisms only got around to making their appearance a couple hundred million years ago.  The more successful species do sexually reproduce.  Most critters are fuelled by sea floor volcanic vents so deep under water that no light can penetrate.  Thus, photosynthesis is a recent development, relative to the timescale of evolution on Earth or Alpha Centauri A III, having emerged only in the last few hundred million years in the form of "riser" organisms that ascended from the volcanic vent ecospheres to the ocean's surface as part of their life cycle.  All photosynthesis is accomplished by a chemical mechanism similar to terrestrial Bacteriorhodopsin, so all photosynthestic organsims have a purplish hue.  Since there is no such thing on this planet as "dry land" — there aren't even polar ice caps, since the CO2 and cloud cover eliminate most latitude-based temperature variation — it goes without saying that no life forms, not even the plantlike ones, have migrated out of the oceans.  However, some plantlike organisms have managed to "colonize" the surface of the oceans, forming floating vegetation mats.  These purple mats float just barely below the ocean surface, and form complete ecosystems unto themselves, with small herbivores that feed on the plants and small carnivores that feed on the herbivores.  Some of these floating vegetation mats are several kilometers across, and would qualify as features big enough to show on a map — except that they're not anchored to the ocean floor and thus tend to meander around in the surface currents and winds.

CN Leonis II:

A lifeless world before the Centaurians arrived, CN Leonis II orbits its star at a distance of two million kilometers, giving it an orbital period (a "year") that lasts only 42 hours.  It is locked in synchronous rotation with the star it orbits; the only thing keeping its day side from frying and its night side from freezing is the steady, howling wind.  The atmosphere resembles that of Jupiter, but with a higher CO2 and a lower water concentration.  Surface gravity is 0.65g.

Although CN Leonis II technically lies within the bolometric Comfort Zone for its star, CN Leonis is a flare star.  Its flares aren't as intense as those on UV Ceti or Proxima Centauri, but they occur with greater frequency.  So, the surface of CN Leonis II can never be terraformed.  However, surface-based energy collectors and subterranean tunnelling have allowed for a thriving underground community, populated by Centaurians and some humans.

Sirius A IV:

The only known planet other than Earth, Alpha Centauri A III, and Alpha Centauri B II to harbor life, Sirius A IV orbits its host star at a distance of 300 million kilometers, giving it an orbital period of about 1.85 Earth years.  It rotates once every 13 hours, and has two decently-sized natural satellites.  It's slightly smaller than the Earth, but is more dense due to the star system's high metallicity, giving it a surface gravity of about 1.1g  Since the star system it's in has only existed for some 300 million years, and since it is so close to its host star, the planet's interior is still quite warm, and its surface is highly tectonically active.  The lower latitudes are too hot to prance around in without reflective shade or air conditioning, but the middle latitudes are habitable and the upper latitudes are actually a bit on the cool side.  (The planet's 27-degree axial tilt helps in this regard.)

("Habitable" here refers to the temperature range, not to its habitability by humans or Centaurians. The atmosphere resembles that of pre-oxygen-holocaust Earth, consisting primarily of nitrogen with substantial amounts of methane, mmonia, and water vapor mixed in, along with trace amounts of carbon dioxide.)

The tropics are not only too hot for human comfort, they're too hot for liquid water, period. Two great oceans gird the planet, one in the far north and one in the far south. These oceans visibly shrink during their hemisphere's summer and grow during their hemisphere's winter. As each ocean shrinks, its salinity increases; as each grows, it gets more and more dilute. Spring and summer are marked by a complete and utter lack of rainfall; autumn and winter consist of almost continuous, torrential rains. Islands and small continents dot both oceans; as the oceans grow and shrink with the seasons, so the land masses' coastlines retreat and advance. Even at the height of summer, though, none of these continents is much larger than Madagascar. Polar ice occasionally forms during the winter darkness, but melts away quickly every spring.

The human population has nicknamed this planet "America".

Ecosystem: Life does exist in the middle-to-upper latitudes of Sirius A IV. Amazingly, life seems to have gotten started in the northern ocean completely independently of life in the southern ocean, as organisms from each region have strikingly different biochemistry from one another. Fossil evidence suggests that neither ecosystem has existed for more than a hundred million years, so it's no surprise that neither ocean has yet produced aerobic life forms. There just hasn't been enough time for them to evolve. The most advanced native organism on the planet is similar in size and structure to a terrestrial mycoplasma, complete with actual DNA in little free-floating plasmid-like loops. The rest of the planet's single-celled inhabitants still use RNA. (Of course, their genetic code(s) are as different from humans' genetic code as the Centaurians' is.) Judging by Earth's evolutionary timetables, cyanobacteria are still about a billion years off — and Sirius A isn't going to stay on the main sequence that long. More likely, the transplanted humans and Centaurians now inhabiting Sirius A IV, and the plants, animals, and microorganisms they have brought with them, will displace most indigenous life forms.

The Human-Centauri Habitat Ring:

Human-Centauri has no planets.  Instead, it has a plane of orbiting debris similar to the debris disk around Vega or the asteroid belt around Sol.  Most of the material in this debris disk is concentrated in a ring that averages 0.02 AU away from the star.  Some of the asteroids in this debris ring are a little bit closer, some a little bit further; an object orbiting exactly at this distance would have an orbital period of 3 days 21 hours 43 minutes and an orbital circumference of 18 850 000 kilometers.  This is somewhat farther away from the star than the conventional comfort zone (which would be at 0.014 AU).

In the earliest history of the star system, long before modern humans or Centaurians existed, Haberd's Brown Dwarf 629 went through a protostar epoch just like any main-sequence star, where it shone very brightly due to its own gravitational contraction (with some help from deuterium fusion in its core) for many thousands of years.  In this protostar phase, it shone more brightly than at any other point in its history (even its current post-artificial-ignition phase).  This protostar phase sublimated all the methane, water, and ammonia ice on every asteroid in the main debris ring, but was too short to sublimate the cometary material in highly elongated, very long-period orbits.  Some of these comets later got deflected by the gravity of the larger asteroids and settled in to much shorter-period orbits.  This means that with the coming of artificial stellar ignition, many many icy objects in the system have been boiling their surfaces into space, surrounded by great clouds of vapor.

Even post-ignition, to gather enough stellar energy for a comfortable surface temperature (or for growing plants on an exposed asteroid surface), an asteroid would have to be locked in synchronous rotation with the star so that one side would heat up to be at or near the substellar temperature.  Despite the debris ring's small orbital radius compared with Sol's asteroid belt, the total combined mass of all the material in the ring turns out to be substantially higher than that of the asteroid belt.  There are dozens of large asteroids, ranging in size from 200 to 700 kilometers across, with surface gravities ranging from 0.5% to 1.5% of 1g  With the ability to position smaller asteroids in close orbits around one another, locked in synchronous rotation with each other, the early colonists also had the option of constructing pairs of "bridged asteroids" for additional living space.

The five largest asteroids are named Human-Centauri I through Human-Centauri V in order of their colonization.  Human-Centauri IV and V are the two largest asteroids in the system.  Another large asteroid became home to the Greeting Area; this only covered a small region of the asteroid's surface at first, but eventually expanded to cover the bulk of the asteroid.  The habitats are all underground or in transparently enclosed areas on the surface.  A few of the exposed surface regions have strong artificial magnetic fields generated by means of supercondicting magnets to keep out cosmic rays and the occasional stellar flare.  The five major asteroids all have space stations in synchronous orbits above their equators, with space elevators leading to (and below) their surfaces.  The experimental scaffolding-connected asteroid pairs have transport tubes between them.  Due to the lack of planetary gravity, many neighborhoods are built entirely out of an underground centrifuge, adjustable to 1g for those coming from Earth, 0.8g for those coming from Alpha Centauri A III, 0.5g for those coming from Alpha Centauri B II, 0.4g for those coming from Mars, etc..

In addition to their official designations as Human-Centauri I through Human-Centauri V, each major asteroid has a name.  Human-Centauri II is "New Mars," while Human-Centauri IV is "New France."  The satellites, natural and artificial, are usually arranged in synchronous orbit and connected to the asteroid by space elevators (even the largest asteroid has a shallow enough gravity well that a space elevator cable won't snap under its own weight).  Shuttles ferry passengers and cargo between asteroids, docking with the smaller asteroids or with the synchorous satellites of the larger asteroids.  The "Greeting Area" asteroid is 200 km across its widest part, with a density of 3 grams per cubic centimeter (along with its requisite synchronous satellites).  This works out to a mass of 1.2 x 1019 kg, giving it a surface gravity of 0.084 m/s2, or 0.0086 g.  It rotates once every 4 hours 20 minutes, giving it a synchronous-orbital altitude of 70 km (at a lateral velocity of 68.7 m/s).  The regular spacecraft docking that occurs at such a synchronous satellite means that good, reliable station-keeping hardware is necessary, because just a fraction of one meter-per-second of delta-V would cause the satellite to get ahead of, or behind, the rotating equator below it, which would pull on and eventually break the space-elevator cable.

Ecosystem: The entire ecosystem in all 5 metropolitan areas has been artificially introduced.  It consists primarily of humans, Centaurians, their pets, oxygen-producing plants (in the star-exposed regions), and food plants and animals for both species.  Agriculture is seen as a somewhat dangerous business by the underground inhabitants, as it requires venturing out into exposed areas to tend the crops.

UV Ceti IV

A granite ball about the size and mass of Mars, cloaked in a thin atmosphere of short-chain hydrocarbons (created by starlight having long ago broken down the original atmosphere of methane).  It orbits its parent star at a distance of 3 million kilometers, three times as far away as what would be the Visual Comfort Zone distance if UV Ceti weren't a flare star.  At this distance, the star appears 3.5 degrees in diameter as seen in the planet's sky, and the orbital period is 3.56 Earth days.  The planet is locked in synchronous rotation with the star, so its sidereal "day" is the same as its orbital period (85 hours 26 minutes), but UV Ceti never appears to move in its sky.  In order for a satellite to be in stationary orbit above UV Ceti IV's equator, it would need to orbit at an altitude of 43,400 km above its surface.

Fusing 1 kg of silicon and oxygen into titanium-44 would release 2.5 x 1013 Joules of energy.  As a quick approximation of what it would take to blow the planet apart, lifting the entire mass of the planet 100 km in the air would take on the order of 1029 Joules, or the fusion of 4 x 1015 kg of silicon and oxygen (about 0.00000063% of the planet's mass).  Accelerating the entire mass of the planet to its own escape velocity (5 km/s) would take 8 x 1030 Joules.

UV Ceti IV has one small (but not tiny) airless moon.  It's 120 km in diameter (sound familiar?), with an average density of 3.35 g/cm3 (sound familiar?).  This works out to a mass of 3 x 1018 kg, a surface gravity of 0.0057g, and an escape velocity from the surface of 82.12 m/s.  The moon is locked in synchronous rotation with the planet, which has circularized the moon's orbit (the moon was originally a captured asteroid).  The moon orbits a scant 10,000 kilometers above the surface of the planet, giving it an orbital period (and, due to the tide-locking, a sidereal "day") of 13 hours 4 minutes.  At that separation distance, UV Ceti IV would have an angular size of a whopping 26.4 degrees as seen from the surface of its moon.  By contrast, the moon as seen from the skies of UV Ceti IV would have a respectable angular diameter of 0.69°, slightly larger than the Earth's moon as seen from Earth.

Centaurian Biology

Centaurians are sexually reproducing, multicellular oxygen breathers with RNA/DNA.  That's about their only similarity to humans.

Seen from the outside, Centaurians look like small versions of the Xorns in AD&D, with four stubby little legs, four long triple-jointed arms each ending in four finger-like tentacles, four mouths with cartilage-ridge teeth situated between and below each pair of arm-pits, and a three-pointed eye-and-ear stalk at the very top of their artoo-detoo-shaped torso.

A three-pronged retractable eye turret sticks up 6-10 centimeters from the top of a Centaurian's torso.  The three eyes on the turret stick out 3-6 centimeters and are 120 degrees apart (facing sideways from a vertical base) with a 118-degree field of view (each); they look like miniature elephant trunks, but unlike elephant's trunks are rigid in terms of their side-to-side motion.  Unlike a Centaurian's foot wheels (see below), the eye turret is not free to rotate.  It's on a "neck" of sorts that can twist up to 90 degrees in either direction.  This allows any one eye to point directly at an object of interest without having to rotate the torso.  Annular muscles on the front of each eye stalk keep the lens clean and control the aperature size.  Focus is achieved by moving the (immaleable) lenses closer to or farther from the photosensitive surfaces at the back of each eye stalk near the center of the turret, like a camera.  Each eye also has vertical "wiggle" muscles that can move the eye up or silghtly down; the photosensitive surface rotates up or down along with the eye-wiggle.  Vision can resolve details down to two arc-minutes, can see wavelengths anywhere from 10 000 Ångstroms to 2 000 Ångstroms (peaking at around 5 500 Å as human sight does), and can see colors in light levels low enough for a human to only be able to distinguish grayscales; however, even in bright light, Centaurians don't have nearly as great an ability to distingush colors as humans do.  They can tell strong shades of blue from everything else, but that's it. Focal deficiencies are rare but do exist; traditionally, these were corrected with glasses that looked and fit like the one-eye eyeglass Gypsy sometimes wears on Mystery Science Theater 3000, but at the time of the story can also be fixed by contact lenses, laser lens sculpting surgery, or sometimes vision therapy.

The center of the eye turret contains the Centaurian's one and only ear, sticking straight up and ending in a closable duct; Centaurians have no sense of smell.  Their sense of hearing has a broader frequency range than a human's does; however, its sensitivity to quiet sounds is not quite as acute.

Body parts requiring rigidity (such as the arms, legs, braincase, and eye turret) have an endoskeleton of a tough cartilage-like substance like a shark does, which ranges in rigidity from the soft, pliable inner pelvic plate to the bone-hard foot wheels.  This cartilagenous substance can heal or "knit" much faster than human bone can, and does not require setting if broken.  Running through the near-centers of their bodies are four backbone-like jointed columns composed of alternating rigid rods and thick-walled pliable sacs made of the same cartilagenous substance, called simply the support columns.  The sacs in the columns can be inflated with air to increase the Centaurian's vertical reach, or deflated to allow the Centaurian to fit through smaller openings without crawling; the sacs in one column can be inflated while deflating the column on the other side, allowing the Centaurian to bend its torso.  They have no hair, feathers, leaves, moss, or the like, but are instead encased in a soft but leathery skin in varying mottled shades of light brown.  They are ectothermic (cold-blooded), and so were traditionally restricted to operating during the warmer A-III daylight hours.  If the temperature falls below 5°C, a Centaurian will automatically hibernate.  The muscles in its extremities will lock into place when this happens, so as to avoid falling off a cliff face should it get caught in a sudden cold front.  The lack of endothermy also means they don't have to eat as much as humans do; one meal every A-III day or two is sufficient.

The four radially-arranged mouths evolved with their ancient ancestors, who garnered most of their nutrition from lichen-like plant matter growing on the sides of cliff faces.  Clinging to the sides of the cliffs was a tricky affair, involving rolling from one set of hands to another, and a proto-Centaurian could never be sure which side of its body would be facing the cliff when it rolled over such vegetation.  Even before the invention of agriculture, anatomically-modern Centaurians gained the bulk of their sustenance from grains that grew on flat ground instead, but still supplemented their diets with cliffside vegetation.  Rock climbing is still a popular sport with Centaurians at the time of the Pentagon War.

Their bodily wastes vaguely resemble the fecal matter of some terrestrial species, but they do not urinate.  Unlike terrestrial vertebrates, Centaurians never went through an evolutionary period where they lived in fresh water and had to excrete excess water via kidneys.  They prefer to drink water as salty as that found in Alpha Centauri A-III's oceans, and find fresh water intolerably bland.  Excessive fresh water intake is toxic to them.

Mounted in the bottoms of each of their four feet are a single, hard-shelled, five-centimeter-diameter retractable wheel.  These wheels evolved in response to the wide, flat plains that cover so much of A-III's land mass, and are present in other Alpha-Centaurian species.  They are spun by means of two central Rotational Muscles (one for clockwise and one for counterclockwise), similar to the rotational muscle group beneath the eye turret but more powerful.  These kinds of muscles are unique to Alpha-Centaurian physiology as they can spin for several thousand or million revolutions in the same direction without getting wound up like a rubber band or anything.

Their reproductive system is a bit odd by human standards in that there is only one Centaurian sex (much like with terrestrial slugs).  Any two Centaurians may mate, and either or both of them may produce offspring.  Centaurians ovulate once every 35 A-III days (26 Earth days), and remain fertile for three A-III days following.  During this time of fertility, they indicate their sexual readiness to each other with honk-like mating calls.  Humans call this their mating "season", being "in heat", "that time of the month", or a number of other terracentric labels.

All Centaurians have a vagina, and a retractible cartilage-reinforced (i.e. constantly erect) penis right next to it on a line oriented 23° from one leg.  Their cloaca sphincter is to one side of this line.  Both the penile tip and a point one centimeter inside the vagina (on the penile side) must be stimulated simultaneously for orgasm to occur. This sexual anatomy requires that two Centaurians mate bottom-to-bottom; their climaxes are usually simultaneous and involve contracting straight down the lengths of their bodies until they are only about 2/3 of their normal height.  The Centaurian "uterus" fills most of the way with oxygenated saltwater and the rest of the way with a slightly heavier (and insoluble) nutrient-rich fluid during the fertility period; the ocean-water and nutrient fluid are internally recycled if pregnancy doesn't occur but are constantly resupplied by the parent's "bubbler" and "albumen" glands if it does.  Almost all litters are of one child; twins are exceedingly rare and triplets are unheard of.  The total gestation period is a little over one-quarter of an A-III year (5 Earth months), and pregnancy shows as a bulging below the central hard-cartilage ring after the 2nd or 3rd Earth month.  Young are born alive and breathing as from a terrestrial mammalian uterus and placenta, although there is no umbilical cord (the Centaurian "uterus" is effectively an egg).  Newborn Centaurians look like miniature versions of adult Centaurians except that their eye turret is disproportionately wide (almost the width of the torso, i.e. as wide as it will be when the Centaurian is an adult).

The parent doesn't produce anything like "milk" and has to feed its baby mashed grains and water.  (Alpha-Centaurian grains are absolutely nutrient-free to a human, consisting of starchlike chains of L-glucose instead of the D-glucose humans normally metabolize; terrestrial grains are downright poisonous to a Centaurian.)  The modern Centaurian parent can buy packaged pre-mashed grains the way humans can buy baby food and formula, but some Centaurian parents insist that it's more rewarding to mash the grains themselves.  Centaurians can extract the water they need by drinking water as salty as their home planet's oceans; however, these oceans aren't as salty as Earth's, which would present a problem to them if they drank from them.  ("Fresh" water is considered bland by Centaurian standards, and most will add a pinch of salt to such water before drinking it.)

The closest living relatives to Centaurians — about as closely related to modern Centaurians as gorillas are to modern humans — are another herbivorous species that looks very similar but is shorter. This close relative also has four feet with wheels embedded in them, and four triple-jointed arms ending in four tentacle-fingers each, but they are built much lower to the ground than Centaurians, being roughly the size and shape of a giant tortoise. Their hands lack a Centaurian's grip strength, because they use them solely to grab handfuls of grasslike plants on the plains — they are not adapted for climbing sheer cliff faces the way Centaurians are. Likewise, the fronts of the mouth ridges that serve as their teeth lack the sharp, incisor-like projections that Centaurians use to scrape baaai(t)i off the rocks.

Genetically, the only similarity between Centaurian chromosomes and human ones is that they are both made of DNA.  The Centaurian genetic code — which nucleotide sequences code for which amino acids — is completely different from terrestrial eukaryotic DNA and RNA, although both are organized into codons of 3 nucleotides each and the same 20 amino acids are coded for.  Centaurian chromosomes are much smaller than human chromosomes, with each Centaurian cell containing about 5000 chromosome pairs.  This is due to the inability of Centaurian chromosomes to exchange genes during meiosis.  Normally, the chromosomes huddle together near the center of the cell, but there is no nuclear membrane confining them.  Their cells also contain organelles and thus probably evolved via the same kinds of symbiotic relationships that created terrestrial eukaryotes; however, don't confuse the organelles that fulfill the same function as terrestrial plastids with actual plastids.  In fact, no analogue to terrestrial mitochondria exists in Alpha-Centaurian cells; cristae-like respiratory structures were apparently present in the earliest double-chromosomed cells and no respirational symbiosis was necessary.

Alpha-Centaurian nerve cells use electrical impulses to convey data, just like terrestrial nerve cells do; however, unlike terrestrial neurons, which send messages from one cell to the next by means of chemical signals, Alpha-Centaurian nerve cells send messages between linked nerves solely by means of electrical conduction.  There are no Centaurian chemical synapses.  You could replace an entire Alpha-Centaurian nerve path (except for the nerve endings which signal muscles and provide feedback) with a wire.  This means that signals not only propagate more quickly up or down Centaurian nerves than they do along terrestrial nerves, they also consume less energy since there's no need to translate them from electrical impulses to chemical messengers and back into electrical impulses every time they cross a cell boundary.  The longest nerves in Centaurian bodies run up-and-down along the four support columns, kind of like a spinal cord, and can easily collapse and extend.  About half way between the tops of the legs and the bottom of the mouths, hugging the geometric center of the body, is a gigantic bundle of nerves that functions as the Centaurian's brain.  This is the only part of the torso intenally plated in a wide, continuous, hard cartilage ring; the rest of the torso is protected by much narrower cartilage ribs, none of which are anchored to other cartilage pieces (they float free so that the torso may expand and contract vertically).

The main "pulsation" movement of a Centaurian body is vertical expansion when inhaling and vertical contraction when exhaling (as opposed to the horizontal expansion and contraction in human breathing).  They express yearning by stretching their arms upwards, not forwards.  The three eyes on the eye stalk have swing-up and swing-down muscles as well as stick-out and shrink-in muscles.  A Centaurian intent on leering at something will bend the top of its torso in the direction he wishes to look and arch all three of its eyes toward it; this results in a triple image, however the visual centers of a Centaurian brain cannot "fuse" the images into a 3-D picture the way a human's can.

For the most part, the internal organ arrangement is as symmetrical as the outside of a Centaurian's body.  They have four lungs and four cowlike stomachs, arranged in a circle between the four support columns.  These lungs are capable of extracting a little oxygen from water as salty as A-III's oceans, but not enough for any kind of sustained physical activity unless the Centaurian is very young.  Thus, you can't drown an adult Centaurian by holding him under water, but you may be able to knock him out that way.

Centaurian skin is quite delicate at birth.  It takes several years to develop the firm, tough, leathery hide of an adult Centaurian.  (It also takes at least one A-III year for the foot wheels to be usable.)  The skin is toughest on the soles of their feet and the bottoms of their hands (which hardens during pregnancy so they can use it for grain-mashing when parents).  It lacks both sebaceous and sweat glands (Centaurians' ectothermy means they don't have excess heat to radiate away; plus, not sweating conserves water).  Despite its similarity to reptilian skin, Centaurians shed continuously as mammals do.  As they age, their skin gradually becomes harder, until after the age of 40 or so Earth years, it is rigid enough to impair their bodies' natural bending.  A healthy Centaurian can be expected to live to the age of fifty Earth years or more, and will be fertile in both directions from the onset of "puberty" at the age of 5 A-III years (7½ Earth years) until death.

The Centaurian immune system does not possess anti-parasite antibodies.  This means they don't experience allergic reactions.

The vocal mechanism of a Centaurian can produce a much wider range of frequencies than a human's can.  Furthermore, the common Centaurian language takes advantage of using more than one mouth to produce some of its syllables.  Certain sounds in the language even require chord combinations of up to four separate pitches.  The most dedicated human attempts to reproduce Centaurian speech with the human vocal mechanism sound like a bad speech impediment at best, and are incomprehensible at worst.  However, since Centaurians lack any kind of nose, they also lack sinuses, so any attempt at reproducing human speech with a single Centaurian mouth sounds like the speaker has a head cold with a stuffed-up nose.  A savvy Centaurian gets around this problem by producing nasal sounds (e.g. the letter "N") with a second mouth on the same vocal pitch.

When they do sleep, Centaurians prefer to sleep standing up, as it allows them to breathe without grating against the floor.  While sleeping, their eyes droop down at an angle from their turret's center, and all three eyes plus the ear orifice are closed.  However, most Centaurians require only 3 hours sleep every Centaurian day (17¾ hours), and can go 2 or 3 days without sleep with no problems.

Centaurian psychology and social structure

Although Centaurians do group-bond and parent-child-bond, they do not pair-bond with their mates, so the "father" of a given baby is not socially important.  Therefore, one's paternal ancestry isn't socially important either, but one's maternal ancestry is.  Centaurians tend to group together in extended families which, for want of a better term, are called "clans" by humans.  Siblings and "mother" parents may be part of this clan, but so may friends born into other clans.  One clan may contain up to 50 Centaurians of all ages; however, 50 Centaurians is kind of pushing it, and when a clan gets that big it will often splinter off into smaller clans.  Adult clan members will usually assist in caring and providing for all of that clan's children, although "mothers" will of course give their own offspring special attention.

Centaurians on their own often have a strong urge to find a clan.  In fact, a Centaurian group-bond is almost as strong as a human pair-bond.  There are even rituals, much like most human cultures' marriage ceremonies, by which a Centaurian formally becomes a new member of a clan.  And in similar fashion, dissociation from ones former clan can be as painful as going through a human divorce, with property disputes and even occasional arguments over child custody if the child is no longer an infant.  (However, it should be noted that the dominant Centaurian cultures do in fact treat adolescents as full adults, much like the ancient Israelites do on Earth; child custody is generally not an issue with Centaurians who are at least 5 A-III years old.)  If a Centaurian's clan has a specific name, the Centaurian will often attach it to its own.

Within a clan, the division of labor is almost egalitarian.  Every clan member has their own specialty, and is deferred to — almost as a "leader" — whenever their area of expertise is called on.  Centaurians don't cook, but if for whatever reason cooking were called for, for example, the other Centaurians in the clan will follow orders from the "cooking expert"; if a bridge needs to be built, they'll follow orders from the clan's "civil engineering expert."  Centaurians within a clan will instinctively divide up the labor, moving almost automatically to whatever tasks are not already taken up by a clanmate.  There are no "menial" jobs, unless a Centaurian's area of expertise applies in a particular situation and its clanmates are overlooking it.  In order for Centaurians to adapt to a human military structure, where there's a commander giving all the orders, they have to train this instinct so that they defer to their commander as the "combat expert," and treat their unit as though it were their clan.

Between clans, however, there is a definite hierarchy.  Clans have dominated other clans throughout most of the Centaurians' recorded history.  Civilization basically began when clans began to make friendship pacts with other clans, either to ensure their mutual survival against a harsh environment or to gang up on another clan that would otherwise dominate both of them.  These larger clan-groups eventually evolved into what, for want of a better word, humans would call "nations."

Taking personal risks for the good of your clan is considered a noble trait.  Hunting parties in the ancient past that deliberately stalked a predator, if the predator was threatening their clan, were lauded as heroes.  (It is telling that, by the time Centaurian civilization reached the point of agrarian settlements on Go'orla, no large preditors existed on any landmass anywhere on the planet.  Centaurians had already wiped them out.)  Taking suicidal actions for the sake of your clan, however, is another matter; this is usually frowned upon (although Centaurian emotional expression doesn't physically "frown" by turning down the corners of one of their mouths or anything).

A Centaurian in heat doesn't exhibit any odd behavior except for the mating call, unless it hears another mating call, in which case it will likely pursue the other call; it can even become aroused by hearing mating calls while not in heat, though this is less common and milder.  However, a Centaurian will in general not be aroused by a mating call that sounds like its own; this tendency away from identical mating calls helps the species prevent inbreeding.  A Centaurian will completely ignore its own mating call and any other mating calls that sound exactly the same; these won't even be a distraction.  (Thus, actively trying to block out the sounds of someone's mating call is viewed as a sign of sexual rejection.)  "Foreign" mating calls are one of the few motivations for Centaurians to venture into the space of other clans, and possibly even join that clan if the Centaurian hangs around long enough after mating and perhaps engages in some food-sharing.

In some areas, particularly where Centaurians need to concentrate, there is social repression of the Centaurian mating call.  Human-Centauri blames much of the Centaurian version of the emotional plague on this social repression.

Unlike humans, Centaurians evolved as herbivorous gatherers, hunting only to kill potential threats (not for food).  Centaurians feel the same way about eating animal meat of any kind (or at least the Go'orla bio-equivalent of animal meat) the way humans do about scavenging off of roadkill; in other words, "Eewww!".  Like humans, though, Centaurians evolved as nomads, and as such have a natural curiosity and a desire to explore.  This is how they found us to begin with.

The user-interfaces of their technology are, obviously, designed for users with 360-degree nonstereoscopic vision, monaural hearing, 4 arms with 4 finger-like tentacles on each "hand", and 4 legs ending in feet with wheels in them.  Any apparatus with "dumb pedals" that don't take wheel input was designed for handicapped Centaurians.  (In fact, inoperability of one or more wheels is probably the most common of the Centaurian birth defects considered crippling; it's usually remedied with something resembling a roller skate.)  Conversely, human tri-vid displays and stereophonic sound systems are useless to them.  Having 4 digits on each hand, their numeric system is in hexadecimal, which made the transition to digital technology somewhat easier for them to handle when they picked it up from humans.

Since Centaurians are only one gender, our concepts of male and female are alien to them (although there are a few gender-specialized species on their own planet they can use as study models).  Next to learning to use Base Ten, the proper use of "he" and "she" and "him" and "her" is probably the hardest challenge facing a Centaurian when it tries to learn English.

The main Centaurian language is verbal; however, it utilizes all four of a Centaurian's vocal mechanisms at once.  Thus, although a human may learn to comprehend spoken Centaurian (with difficulty), he or she cannot learn to speak it.  The written language is phonetic, where each symbol stands for an atomic or nearly-atomic sound in the spoken Centaurian language.  Written Centaurian is much easier for a human to get a handle on than the spoken language is.

Because Centaurians are cold-blooded, they don't express affection by hugging or nuzzling.  Centaurians also have no circadian rhythms tied to Go'orla's year; thus, they don't don't feel the strong urge that humans do to hold annual festivals or holidays.  Furthermore, they are simply not as superstitious as we are.  In the words of one Centaurian psychologist, "If humans had evolved on Go'orla rather than Earth, they would hold a big festival every 53 [A-III] years to celebrate [Alpha Centauri] B's peak brightness and closest approach, and dance for their gods in the intervening years to pray for the fading light's return.  They would attach spiritual, even omen-like, significance to the brightness-phases of our tiny moon, and fear for the end of the world when the moon partly eclipses B.  But their celestial superstitions mean that they would also have been able to predict the precise motions of these bodies millenia before we could."

Body language equivalents
agreeing nod tentacle-finger pointing upward
shaking head "no" pushing-away gesture with hand
pointing at X bending torso and craning all 3 eye stalks at X
sigh sigh
chuckle gutteral snort with 2 mouths
shrug tilting slightly away from listener
furrowed brow closing other 2 eyes

Centaurians feel perfectly comfortable wheeling around in public with no clothes on.  (It should be noted that some tribes of humans are at home with their own public nudity, too, so this shouldn't come as too much of a surprise.)  The placement of the Centaurian genitalia means they aren't normally visible while standing up, so even those few Centaurians with a "Victorian" sense of shame can hide their anatomy without cloth.  Protective clothing is usually designed to protect from the wind rather than the cold; the species' lack of endothermy means that wearing clothes to "hold in ones own body heat" is ridiculous.  When clothing is worn, its colors are either terribly drab or the most striking, gaudy clashes of solid toddler-toys-bright pastels imaginable to the human mind — and in either case slight blemishes or stains will go completely unnoticed.  (This is all because of Centaurians' reduced color sensitivity.)  Shoes are sometimes put on infants' tender feet, and are often worn by adults whose feet are more sensitive; but they always have a hole in the bottom for the wheel.  Body wraps that fit snugly below the mouths are another staple of those Centaurians who wear clothes.  Rarely will a Centaurian submit to clothing that hangs down from the shoulders over any of the mouths, and all clothing for the top of the body must have a hole big enough for the eyes-and-ear stalk to fit through. Since the rank structure of human-inspired militaries (such as the HCDF) requires the display of rank insignia, Centaurians in the HCDF will wear a rank insignia on one or two arm bands while on duty.

Since Centaurians can rest standing up, they don't use chairs.  This makes titles such as "chairperson" sound a little odd.

Politics at the time of the Pentagon War


The Solar Federal government, headquartered in New York City, is similar to the representative-democracy of the Constitutional United States, considering it grew out of the U.S..  Its Territories do not have representatives in the House or the Senate; its States do.  Early in its off-Earth-colonization period, even moderately populated territories were granted Statehood almost as soon as they requested it.  After the break-off of Sirius, the Solar Federal government throttled way back on State admissions; there hasn't been a new State admitted since Ganymede.

States: North America, South America, Eurasia, Asia Minor, China, India, North Africa, South Africa, Australia, Antarctica, The Moon, Mars, North Mars, Ganymede.  Territories: all other Solar system bodies that aren't States, Lalande 21185, UV Ceti (and Luyten 726-8 A).  Mercury is a major antimatter production facility.

The intelligence and security functions of the 20th-century FBI, CIA, NSA, and Secret Service are rolled together into the Solar Bureau of Investigation, or SBI.  Like the NSA, it's a scary organization.  Like the FBI, it's also rather clumsy.

The Sol/Alpha-Centauri hyper hole orbits the sun with an aphelion distance of about one billion km, putting it is aphelion about two-fifths of the way between Jupiter's aphelion and Saturn's perihelion.  Being the first hyper hole, the fact that it would orbit the sun like any other planet wasn't known for certain and definitely wasn't worried about much; accordingly, its orbit is highly eccentric as planets go, with a perihelion distance of only 480 million km, grazing the outermost reaches of the main asteroid belt.  (This gives it an aphelion velocity of 3500 m/s.)  A few kilograms of asteroid belt dust have already fallen through it; but, fortunately, its orbital plane is tilted from the ecliptic enough that it will never physically intersect Jupiter or its moons.  (At least, not within the next few millenia.)  Given its semi-major axis of 740 million km, its orbital period around the sun is a hair shy of 11 years.  The Sol/Sirius hyper hole, on the other hand, has a nearly circular orbit not too much farther out than that of Jupiter, with an orbital period of about 12 years.  This gives the Jovian system a high degree of economic and military significance, since every few years one of the two holes comes close enough to Jupiter to make the gas-giant a convenient first stop for travellers or attackers.  Thus, by the time the War breaks out, most of the military might of the Solar Federal government has been concentrated in the Jupiter-orbiting spacecraft hangar known as Station Jove.

The principal language spoken by all humans, Solar or otherwise, is English.

Alpha Centauri:

Alpha Centauri A III is still the central power hub of the Alpha-Centaurian government.  The lesser colonies on the planets in the three-star Alpha Centauri system that used to be lifeless — and even the large, self-sustaining "floating city" colonies on Alpha Centauri B II — are all subsidiary to Alpha Centauri A III.  In that sense, A-III holds much the same role that Rome did to its subject nations, as the center of an empire.

At any one time there will be one clan leading A-III.  The various duties involved in running the nation — military, diplomatic, economic, etc. — are divided up among clan members; there is no one individual within the ruling clan that has "absolute authority".

The Centaurians were more cautious about the placement of the Alpha-Centauri/Sol hyper hole than their Solar counterparts were.  It orbits Alpha Centauri A on the same ecliptic plane as the star's 3 planets, in a nearly-perfect circle 2 A.U.s distant from the star.  The Alpha-Centauri/CN-Leonis hyper hole follows the same orbit on precisely the opposite side of Alpha Centauri A.  The two holes were intentionally placed so that they'd always be on opposite sides of the star system; this allowed the Alpha Centauri system to place itself as a "toll road" for all traffic between Sol and CN Leonis.  (There's no system transit fee or anything; the long transit distance simply makes it convenient for spacecraft to reload and/or refuel in-system).

CN Leonis:

CN Leonis is a monarchy, always ruled by a single Centaurian clan.  The second planet from the primary, since it was the most hospitable, has the highest population and is the system capital.  The ruling clan can only be deposed by force.  Like Alpha Centauri's government, the ruling clan governs as a whole; there is no one individual with higher authority, although there are experts within the ruling clan who have specific areas of authority.  Warlike tendencies abound; one would call the government "patrist" save for the fact that there is no biological distinction between a Centaurian father and mother.  The humans which are not officially slaves of the Alpha-Centaurian majority are treated little better than slaves.  The inability for humans to speak the Centaurian language (although some have learned to understand it without their masters' knowledge) is just one of the many differences held by the local Centaurians as a sign of their species' superiority.

The scariest Leonians, though, are those subservient humans who have sworn their loyalty to the CN Leonis nation above their own lives.  These hyperpatriotic fascists form the backbone of the Fanatic Brigade, that sect of the Leonian military willing to go on self-orchestrated suicide missions or other military tasks with low odds of success.  Many of them were tortured and isolated early in life by local Centaurians to ensure this kind of behavior.


Authoritarian empire, with the capital on Sirius A IV.  There is a figurehead electorate, but, like the U.S. Federal government of the 18th-20th centuries (and the modern Solar Federal government, for that matter), voters cannot vote on issues, only candidates.  The real ruling faction makes it to power the same way the ancient Roman emperors did, i.e. by defeating the previous faction.  The electorate gives the emperor a good look at public opinion, but the word of the imperium is always final.  A figurehead Ayatollah serves as the state's diplomatic arm.

Every half-century, Sirius A and Sirius B pass within 8 A.U. of each other, meaning the maximum stable distance at which any object can orbit Sirius A or Sirius B is 2 A.U..  Sirius A IV orbits Sirius A in a 2 A.U. circular orbit, putting it right on the cusp of that maximum stable orbital distance.  This means that both the Sirius/Sol hyper hole, and the Sirius/Human-Centauri hyper hole, had to be created inside Sirius A IV's orbit.  The Sirius/Sol hyper hole, for example, orbits Sirius in a circle only 280 million km in radius.  Sirius is the only nation whose hyper holes orbit their star more closely than the capital world does.


A participatory democracy. Those that wish to participate, participate; those that don't, don't. (Politics just plain does not interest some people, and there's no social pressure to vote if you don't want to.) Major nonemergency issues with far-reaching fiscal or policy implications must be decided by anonymous popular vote. The leader — officially refered to as the "Chairholder" even if of Centaurian physiology — as well as other political officers are elected on a more or less regular basis, using an instant-runoff voting system to avoid spoilers. It should be noted that any persons running for an elected office are scrutinized thoroughly for any signs of neurotic behavior that could interfere with their work if elected (this scrutiny is much more severe than the usual Emotional Plague weeding-out that the rest of the populace is subjected to).

The lack of Emotional Plague behavior among the general population means that the Human-Centaurian Defense Force is going to have hardly any of the usual mindless, fascist soldiers in it.  This presents a lot of manpower problems from the standpoint of system defense.  HCDF members are very serious about their work, but are usually sickened by the prospect of making a career out of fighting.  Sometimes the knowledge of the terrible power of the Emotional Plague so prevalent in the militaries of the other star systems is the only thing keeping the HCDFers vigilant.  History is a deadly-important subject in the Defense Force academy, since most recruits have grown up entirely within Human-Centauri culture and have never had direct Plague contact.  Note that prior to the war, participation in the HCDF was entirely voluntary, and volunteers could quit at any time.  With the war, tours of duty and even small-scale non-combat drafting were instigated.

Land areas are not divided into arbitrary "countries" or "provinces" or "congressional districts"; instead, each of the five metropolitan areas is partitioned according to the solid asteroids it's made up from.  "Scaffolding cities" consisting of very small asteroids networked together into a single larger living space are treated as a whole asteroid-like partition.  For locale efficiency, the postal and transportation services have divided each asteroid into a 3-D grid of 20 kilometer cubes, but the inhabitants still navigate locally using the older asteroid partition naming system.

The Human-Centauri/Sirius and Human-Centauri/CN-Leonis hyper holes both orbit the star in the same ecliptic circle, some three million kilometers farther out than the habitat ring.  This gives them an orbital period of about 11 days, and an orbital velocity of some 39-and-a-half kilometers per second.  Unlike Alpha Centauri, these two hyper holes are only a few tens of thousands of kilometers apart, with orbital periods lined up to within a hair's breadth of one another.  Human-Centauri had no desire to become a "tourist spot" for transients not interested in the system itself.

Hyper Bombs and Hyper Space

A "hyper bomb" is a phased antimatter bomb, as developed by the Mad Scientist around 150 AC.  Physically, it is an immense device, requiring the containment of 250 kilograms of positrons.  This requires literally millions of smaller positron-containment units to be interleaved with the units that store the 250 kilograms of free electrons, so that the electrostatic forces don't tear the bomb apart.  Thus, it is too big to deploy on a normal spacecraft-launched missile.  It is not too big, however, to be deployed by a full-sized fighter programmed for a suicide mission.

Successful detonation requires the 250 kilograms of positrons and 250 kilograms of electrons to be brought together on a wide, flat plane of annihilatory contact.  If aligned just right, and fed into one another at the proper rate, the first layer of positrons and electrons will emit all of their annihilation gamma rays in phase with one another, and thus stimulate the next layer of e+ and e- to annihilate and emit their gamma rays in phase with the first layer.  The result is a unidirectional, phased, coherent wavefront, much like what one would expect from a gamma ray laser.  This phasing of the bomb's output packs so much power into the beam in such a short space that it actually exceeds the Energy Density Limit for the universe, sending half the energy into a super-powerful gigaton-of-TNT-equivalent beam of destruction called the "foreflash", in Real Space, and the other half of the energy through a hyper-spatial hole, or "hyper hole", into Parallel Space.

(Some have theorized that the twin beams of intense gamma rays emitted by a Gamma Ray Burster as it collapses into a black hole may also exceed the Energy Density Limit for the universe, and would thus also create hyper holes.  If this is so, then the amount of gamma ray energy we're measuring when we detect a Gamma Ray Burst is only half the amount of energy the gamma-ray beam actually emitted, since the other half will have vanished into Parallel Space.)

The hyper hole stays around after the blast subsides.  In fact, it behaves like an ordinary gravitational object, obediently orbiting any nearby star or planet.  Gravity is the only known force that will affect a hyper hole, however.  You cannot grab onto it and "pull" with a physical object or a static-electric or magnetic field, nor can you "push" it with a blast of vapor.  Even attempts to move a hyper hole with a gravitational tug a la Edward Lu et al. have failed.  Furthermore, all attempts to detect its actual gravitational mass (by putting known masses really close to it and seeing how those masses move) have come up with zero or as close to zero as can be tested.  And, finally, since the wavefront from a phased antimatter bomb is directed, the hole is, too — it is two-dimensional and two-sided.  And it has a definite circular outer boundary some 200 meters in diameter.

Three other models for hyper holes that I've rejected:

  1. Making the hole single-sided, with the "rear" side acting like an infinitely hard, infinitely inertial mirror to any matter or energy coming into contact with it.  There are conservation-of-momentum issues that come about when dealing with hyper holes that supposedly have zero gravitational mass, but infinite inertial mass.  Worse, though, is the issue of how a spacecraft under the influence of a Zero Drive can transit a hyper hole while the hole's relative velocity, at this particular point in its orbit, has it moving hard-side-forward.
  2. Making hyper holes spherical rather than circular.  This would avoid all the problems that could come up with a spacecraft at Absolute Zero Velocity trying to intercept a hyper hole that's moving at an angle, or trying to emerge from another hyper hole after shutting the Zero Drive off.  Boundary shear would still occur, too.  However, a spherical hole in space causes some of its own issues, such as the fact that there is now no preferred direction to enter a Hyper Hole from, meaning that one Gate Guard won't be sufficient protection and that staring into it from any angle results in seeing the other system from that direction.  Worse, since the surface is curved, a large object stuck part way through a spherical hyper hole would have a concave border on both sides!  Either that, or the hole would have to have an "interior", which causes no end of problems.
  3. Keeping the holes double-sided, but having the "rear" side unlinked, i.e. behaving like the rogue hyper hole at UV Ceti.  My original model didn't involve any kind of permanent link-tunnel between two hyper holes; it required the two holes to be precisely lined up with each other because anything that entered a hyper hole travelled through parallel space at infinite speed.  An object came out the other side because the other hyper hole happened to lie along the object's flight path through parallel space.  At the time I came up with this model, I hadn't yet taken high school physics — I didn't know anything about orbital mechanics, the lack of a preferred inertial reference frame to the universe, etc..

Anything entering a hyper hole (from either side) will move through an infinitely-thin fourth-dimensional layer of hyperspace into Parallel Space, a three-dimensional universe fourth-dimensionally adjacent to our own.  Little is known of the nature of this Parallel Space, except that everything that has gone into it has disappeared for good, and that nothing ever comes out (not even light).  Theoretically, matter, energy, and even time as we know them should have no meaning whatsoever in Parallel Space.

When two hyper bombs are detonated facing into one another and within a few seconds of each other, the two hyper holes that are created become "linked".  They will forever after face each other, no matter how far or in what direction either of them moves in Real Space.  (A side effect of the link-creation process is that the Parallel-Space portion of each bomb's foreflash will race out of the other bomb's newly-created hyper hole as a "backflash", with all the punch of the bomb's Real Space foreflash.)  This link means that anything entering one hyper hole will go into Parallel Space, travel in a straight line however it is that things travel in Parallel Space, and emerge out of the other, linked hyper hole the very next instant.  The actual transit time is undetectably small and is probably mathematically zero.

Note that the two holes must always face in the same direction to ensure that the momentum of transiting objects is conserved:

Two linked hyper holes that face different directions would spit out a transiting object in a different direction than the one it entered from, violating the conservation of momentum.

(Such a requirement also ensures that the angular momentum of transiting objects is conserved, although this can also be accomplished by having the two holes rotate at the same rate regardless of facing.)

The weird thing is, since both hyper holes are two-sided, anything entering from the "rear" of one hyper hole ALSO makes this transit, and comes out on the "rear" side of the other one.  So a spacecraft in Sol, entering the side of the Sol/Alpha-Centauri hyper hole that faces Alpha Centauri, will emerge from the Alpha-Centauri/Sol hyper hole also facing Alpha Centauri; but if the same spacecraft instead enters the side of the Sol/Alpha-Centauri hyper hole that faces away from Alpha Centauri, it will emerge from the Alpha-Centauri/Sol hyper hole facing away from Alpha Centauri.

There's a second problem with the conservation of momentum that I have yet to solve. Two linked hyper holes in two different star systems are orbiting their parent stars at different velocities. The Sol/Sirius hyper hole is orbiting Sol at around 5300 m/s, while the Sirius/Sol hyper hole is orbiting Sirius A at around 13200 m/s. We know from measurements of Sirius's proper motion and radial velocity that Sirius itself is moving at ~19000 m/s relative to Sol. The orbit of Sirius B around Sirius A is inclined at 136° from our vantage point here in the Sol system, and any planets it has will orbit in the same plane; the engineers who detonated the Sirius/Sol hyper hole would have put it in the same orbital plane as well.

Let's say that, relative to sol, at one moment the Sol/Sirius hyper hole is moving at 5300 m/s toward galactic east, and the Sirius/Sol hyper hole (8.6 light-years away) is moving at 7000 m/s toward galactic north. A slow-moving freighter that edges into the Sol/Sirius hyper hole at only 1 or 2 meters per second, relative to the Sol/Sirius hyper hole, would come out of the Sirius/Sol hyper hole at the same 1 or 2 meters per second but relative to the Sirius/Sol hyper hole. Its velocity relative to Sol has just been changed from 5300 m/s eastward to 7000 m/s northward!

We know how this conundrum is solved in the case of wormholes.  The ends of a wormhole have their own mass and electric charge, like any other object in the universe.  Anything that enters one end adds its momentum to that end of the wormhole, just like in an inelastic collision.  Anything that exits one end subtracts its momentum from that end of the wormhole, just as though a physical object had split in two.  So, you end up with either extremely massive wormhole ends getting nudged ever-so-slightly every time something transits through them, or you end up with low-mass wormholes getting bopped around all over the place.  Unfortunately, hyper holes have zero mass, and never gain mass.

The only solution I can think of to this conundrum, other than having the departure side of the link spit out the spacecraft with a huge velocity relative to the hole, is to have the holes themselves always move in lock-step with the same velocity. This would mean they couldn't actually orbit the stars they were created around; instead, their velocities through space would always be tied together. This would wreak havoc on the scenarios for creating them, and also mean that as Sol and Sirius drift through space at 19 km/s relative to each other, at least one of the two hyper holes would have to get progressively farther and farther away from "its" star until the hole was way out in interstellar space.

Another alternative is to just say that in this case, the conservation of momentum is violated. But on average, as spacecraft enter one hole and leave the other, the momentum changes will eventually more-or-less cancel out. They will never cancel out perfectly, however, and can intentionally be made more and more unbalanced. And, frankly, if I'm going to allow hyper hole transit to violate the conservation of momentum, there's no need to have both linked hyper holes face the same direction any more.

The diameter of a hyper hole varies with all the little, subtle, uncontrollable nuances of the hyper bomb that created it, anywhere from 200 to 210 meters.  It is also not perfectly circular, although it's quite close.  If two hyper holes are created simultaneously, such that they become linked, the linking process will ensure that the two holes are exactly the same shape and size, even if that shape isn't a perfect circle.  However, a hyper hole's outer circular boundary is infinitely sharp and will shear off any part of a transitioning object sticking out past it — this is called, originally enough, "boundary shear".  Spacecraft wishing to transition through a hyper hole therefore must be built so that their maximum cross-section never exceeds 200 meters, and have to aim for the hole's dead center and fold down any communications antennas before proceeding — slowly — to the other side.  Entering the hole on a perpendicular course is not necessary, though, since any particle of the spacecraft entering from one side will instantly appear at the other side at the same distance from the remote hyper hole's center and moving with the same velocity as when it entered.  In fact, the matter and intermolecular bonds going "through" the hole exist at both ends as though the hole wasn't there.  From the standpoint of the transitioning observer, looking through the hyper hole is like looking at the destination star system, since light travels through it just as infinitely-fast as matter does.

Besides the potential benefit for shortening interstellar travel distances by a factor of several million, the extremely costly hyper bomb is also useful as a doomsday weapon of last resort.  The intensely powerful foreflash travels over ten thousand kilometers before the phased nature of its gamma ray photons dissipates.  If detonated right next to a planet, and pointed straight into the planet's core, the foreflash will drill a path of destruction straight through the center of the planet, turning all the rock and metal it passes through into supernova-hot plasma.  The resulting nuclear fusion that this heat creates will in turn will vaporize a shaft of material several kilometers in diameter surrounding the foreflash shaft itself.  And when that much solid and liquid material suddenly turns into a gas, the resulting pressure is more than enough to break the whole planet apart.  In less than an hour, there will be a red-hot expanding cloud of small asteroids where the planet used to be, or at the very least the planet will be turned inside-out in a jumbled heap.

Near the end of the story, our heroes discover that by creating a Zero Velocity effect around themselves and their craft (by using the late Mad Scientist's Zero Drive) before they enter a hyper hole, they can enter a state of "Limbo" neither totally in Real Space nor totally in Parallel Space.  They exist in Real Space as tachyons, and in Parallel Space as whatever unknown stuff Parallel Space things are made of.  They can see the light given off by stars and radio beacons, and even be affected by gravity (which seems to operate at infinite velocity, at least in Limbo).  Since they are tachyonic, and therefore on the other side of the energy curve, they have to maneuver "backwards"; i.e. firing a thruster (or throwing any material from inside the Zero Velocity effect to the outside, for that matter) will accelerate the craft toward its own exhaust rather than away from it.  The accelerations given to their craft while in limbo are "remembered" by the craft, in the directions they would be applied if they were in Real Space as a normal inertial object, when the craft exits limbo and shuts off its Zero Drive.

The Quantum Confinement & Constriction Field

The Centaurians developed this technology over a century prior to human contact.  A QC&C field is neither an electrostatic nor a magnetic field; I'd call it a "strong nuclear force field" if I wasn't afraid of the unforeseen consequences a field made out of that force might have.  A Quantum Confinement & Constriction field takes a considerable amount of energy to create, but once created is practically self-sustaining.  It can be shaped to form a "cell" confining some subatomic particles, which can then be constricted to force the particles into quantum states they would normally avoid.  A QC&C cell can only confine a handful of subatomic particles at a time, however, and performing quantum constriction on more than two nuclei at once is hellishly tricky.  The field can also convert a limited amount of incident electromagnetic radiation into useful electric energy with almost 100% efficiency, so when a charged particle strikes a QC&C field and rebounds off of it, the resulting bremsstrahlung can be recaptured and fed back into the system to sustain it.

At maximum constriction, the inside of a QC&C cell is extremely tiny.  It's smaller, in fact, than the Compton wavelength of the particles contained within it.  Since a confinement to a very tiny region means you know the location of each particle with great precision, this means (via Heisenberg) a correspondingly large uncertainty in the particles' momentum and therefore their energy.  A number of extremely short-lived particles are thus created when a QC&C cell constricts, but they all go away when the cell re-expands.  This property makes a QC&C cell an ideal environment for particle physics experiments (much cheaper than a particle accelerator), but thus far has no practical applications.

One consequence of the existence of QC&C fusion is that there is no longer any such thing as a rare element.  Any two nuclei can be fused together in a QC&C cell.  Therefore, any isotope of any element can be synthesized by fusing together 2 lighter elements.  The process always consumes more energy than it produces when synthesizing elements heavier than iron, of course, but when you have QC&C proton fusion at your disposal, energy is cheap.  Gold is no longer a rare and valuable commodity.  The metals needed to build spacecraft are never in short supply.  Most importantly, no one place can ever have a monopoly on any one element, so a rich deposit of (say) praseodymium no longer makes for a super-valuable piece of real estate worth warring over.

QC&C proton-proton/deuteron-deuteron fusion:

QC&C field technology allows a "cold fusion" technique involving super-tight quasi-magnetic confinement at the quantum level.  The protons are constricted so close together that they have no choice but to tunnel through the Coulomb barrier.  This eliminates the traditional problem of proton fusion taking a very very long time to progress (the catalized CNO reaction inside the core of large stars has a typical reaction time of about a thousand years).  However, a separate QC&C cell is required for each and every pair of particles that need to undergo fusion, so even in a "massively parallel" system of many such cells the amount of material undergoing fusion at any one time is going to be very small compared with the mass of the apparatus.  Furthermore, a separate "stage" of such cells is required for each step in the fusion chain.  A typical QC&C proton fusion reactor has 2 stages: A proton-proton stage, which feeds the resulting deuteron into a subsequent deuteron-deuteron stage.  (Actually, it's a proton and a neutral hydrogen-1 atom (protium) that get fed into the first stage.  This is so the positron created by the proton-proton constriction can annihilate with the electron; the resulting gamma ray photons are intercepted by the QC&C field and turned into useful electric energy.)  The deuteron-deuteron stage produces 89.2% of the system's total energy.

The need to have a separate QC&C cell for every pair of particles limits the maximum thrust a proton fusion engine can produce to a few g.  In fact, to produce enough thrust to accelerate a 1000-tonne spacecraft at a mere 2.5g, assuming a single QC&C cell can force a whopping 100 billion reactions to occur per second one-after-another, you would need an array of 2.2 x 1015 QC&C cells for the first proton-proton stage, and another 1.1 x 1015 QC&C cells in the second deuteron-deuteron stage — and that's assuming all of the energy released by the full proton-to-4He fusion process is funnelled entirely into the kinetic energy of the exhaust.  Fitting that many cells into a 10-meter-square array would mean each cell could be no larger than 200 nanometers across.  For this reason, many QC&C fusion powered spacecraft are built with only a deuteron-deuteron stage, and must carry deuterium in their fuel tanks.

Even so, a fully-fuelled fighter deployer with its fighter complement docked masses about 4 million tonnes.  To get a 2g acceleration out of such a beast with deuteron-deuteron QC&C fusion, you'd need to burn 2360 kg of deuterium per second, which works out to 3.5 x 1029 reactions per second, which (assuming one QC&C cell can perform 1011 reactions per second) requires 3.5 x 1018 QC&C cells.  If a QC&C cell is 200 nm across, you'd need a square grid a ridiculous 374 meters on a side.  Thus, fighter deployers cannot use a square grid.  They must use a cubic grid, a stack of square grids that's (say) 30 meters on a side and 155 layers thick.  The layers must be aligned such that 155 pairs of deuterons can enter each column of QC&C cells simultaneously, then each cell will constrict around an individual pair in that column.

Proton fusion, combined with electric arc-jetting, is the main thrust energy source of the Bussard-ramscoop "scramjet" spacecraft that were the staple of interstellar travel before the advent of linked hyper holes.

Assuming 100% perfect efficiency, and not adjusting for relativistic effects:
Exhaust velocity from an engine using both stages (proton+deuteron) of QC&C fusion: 0.120c.
Exhaust velocity from an engine using both stages of QC&C fusion, but not using the energy released from the positron annihilation to accelerate the exhaust: 0.115c.
Exhaust velocity from an engine using just the second stage (deuteron) of QC&C fusion: 0.113c.
Exhaust velocity from an engine using just the first stage (proton) of QC&C fusion: 0.039c.
Exhaust velocity from an engine using the first stage of QC&C fusion and not using the energy released from the positron annihilation to accelerate the exhaust: 0.021c.

Active Radar Absorption:

Also known as Radar Invisibility.  A QC&C field is spread over the entire hull of the spacecraft, tuned to absorb incident radiofrequency radiation.  This requires a bulky array of emitters, costs a tremendous amount of energy to switch on, and can only absorb a few Watts of incident radiation.  It also won't prevent the spacecraft's prodigious thermal emissions from being detected.  Its main military purpose is to prevent enemy weapon systems from attaining a radar lock, so as to make the spacecraft harder to hit.

Other technology available to all systems at the time of the Pentagon War

Positron factories:

Making positrons is easy.  Make some fast electrons — by electrostatic linear acceleration, magnetic (synchro)cyclotron acceleration, high-energy laser, or what have you — shoot them at a dense target of the proper thickness to create gamma rays, and when those gamma rays pass close to another nucleus in the target, voilá, an electron-positron pair is born.  The tough part is separating these newly-minted positrons from all those noisome electrons traipsing about in the target before they annihilate, and packaging them up in useful, transportable, failsafe bundles afterward.  Antimatter containment is usually achieved through good old-fashioned magnetic circulation, surrounded by a QC&C field to trap accidental strays and recapture the energy that would otherwise be lost to cyclotron radiation.  A single containment unit, about the size of a hockey puck, is limited to a million coulombs of stored particles, which is about 5 milligrams of positrons or 10 grams of antiprotons.

Human-Centauri got around the macro-electrostatic charge problem by storing antimatter in the form of neutral antihydrogen.  They lowered the temperature to a few millionths of a degree above absolute zero, which causes the antihydrogen to condense into white snowflakes.  Charles Pellegrino, in Flying to Valhalla (1993), claimed that "wave functions do not overlap enough to produce an appreciable reaction" if the temperature is less than 20 microKelvins.  Such whiteflake antihydrogen can be suspended inside a normal-matter fuel tank and kept away from the tank walls by electrostatic forces and/or magnetism.  Note that the density of frozen antihydrogen would be the same as the density of frozen hydrogen, 0.088 grams per cubic centimeter; so a hundred tonnes of solid antihydrogen would occupy 1136 cubic meters of space.

Aside from such a dangerous balancing act, Uncharged particles can only be contained by means of QC&C fields, and one QC&C field can only act on a handful of particles at a time.  Even a massively-parallel array of QC&C fields, as is used in proton fusion, can't contain any more antimatter per cubic centimeter than a conventional magnetic containment unit operating on charged particles.  Storing the antiprotons inside fullerenes won't help either, since you're still not balancing the negative charge of the antiprotons with positive charges (doing so would compromise the electron-cloud-containment strength of the fullerenes), and you'd incur a huge mass penalty (60 or so worthless carbon atoms for every antiproton).

What this all means is, although it's much harder to manufacture a single antiproton than it is to manufacture a single positron, it's far easier to manufacture and store a given mass of antiprotons than of positrons.  Depending on its size, a positron factory can manufacture anywhere from ten grams to one kilogram of usable positrons per year.

Due to the radiation and containment-failure hazards, all antimatter factories tend to be located in uninhabited areas, on uninhabited planetary bodies, or on artificial satellites.  At the time of the Pentagon war, Human-Centauri has fewer positron factories than any of the other 4 nations.

Proton-deuteron hot fusion:

Before Second Contact with the Centaurians, which resulted in humanity getting QC&C technology, Earth had been working on making hot-fusion technology a practical reality for over a century — tokamaks, polywells, etc..  The result, from these totally independent lines of research, was the hot-fusion of deuterium with protium (normal light-hydrogen), self-sustaining without the need for tritium.  (Due to the higher temperature required for proton-deuteron fusion, tritons are usually introduced to start the reaction but are not required to sustain it.)  Proton-deuteron fusion results in a helium-3 nucleus and a gamma ray photon, so protium-deuterium hot-fusion reactors are designed with very high density plasma to maximize the chance for the gamma ray photon to get absorbed and converted into thermal energy.  The process isn't perfect, though, and a few stray gamma ray photons escape, which means spacecraft sporting such engines need a little bit of ionizing-radiation shielding between the reactor and the occupants/electronics.  The process also occasionally results in deuteron-deuteron fusion, which makes a free neutron half the time it happens; the reactors are engineered to minimize the chances of these unwanted deuteron-deuteron reactions, but very small amounts of radioactive contamination are inevitable.

My original thinking was that proton-deuteron hot-fusion technology didn't come into existence before Second Contact, and thus always lived in the shadow of QC&C fusion.  However, I'm beginning to rethink that position.  If hot fusion did pre-date QC&C — and thus would also have pre-dated Second Contact — it could be used in fending off the inevitable Centaurian counterattack.  We could even have started colonizing the moon before Second Contact.  Perhaps development of this technology took on a new urgency after First Contact, and some (but not all) of the ICBMs in our arsenal when Second Contact finally arrived would have had fusion engines.  ("I got into fusion research because I wanted to save civilization in the long run.  Now, it might be the only thing that gets humanity through the next decade.")  If that was the case, it would not be inconceivable for a few hot-fusion power plants to be built on Earth before QC&C fusion took over.

The energy produced by the fusion of a proton and a deuteron into a helium-3 nucleus is 5.4935 MeV, including the energy of the gamma ray photon.  Ounce-for-ounce, this is 41% as much energy as is released by the fusion of protons into alpha particles.  (For comparison, the fusion of deuterons into alpha particles produces 89.2% as much energy as the fusion of protons into alpha particles.)  However, hot-fusion is far from perfect, and allows much of the unburned propellant through into the exhaust.

Deuterium is more expensive than ordinary protium, but the reaction doesn't require QC&C cells and can happen in bulk; a protium-deuterium hot fusion engine of a given mass can generally produce much more thrust than a QC&C engine of the same mass.  However, it is not nearly as efficient, with an exhaust velocity of only 0.044c.  This is less than two-fifths of the exhaust velocity a proton fusion engine creates (less, even, than 2/5 of what a QC&C deuterium engine creates), which means it's only 15% as energy-efficient as a QC&C deuterium engine.  Nearly all of this inefficiency is due to unburned protium and deuterium making its way into the exhaust, although a little of the inefficiency is due to its high thermal component (unlike QC&C exhaust, hot-fusion exhaust has a strong blackbody glow, with an effective temperature above the point at which all objects appear blue-white to human eyes).  In this regard, it's like a solid rocket booster: high thrust-to-weight ratio, but low Isp.  It is the preferred means for propelling spacecraft too small to sport a QC&C engine, or which need to produce very high thrust levels.

Types of spacecraft:

Newman Energy Machines:

At one point, I really believed that these things worked.  Now that I know they're pretty much a load of wishful thinking, though, I have no intent of including them in my story.  Their technological, economic, and social implications would be enormous.  Hot fusion wouldn't play such a crucial role in energy production any more.  Fusion may in fact be secondary to spacecraft thrust; synchrotron beams can have specific impulses in the millions of seconds, and Newman devices would mean practically limitless electric energy.

Even while I still believed in Newman's electromagnetomic motor, though, I realized that including them in this future history would risk alienating a lot of my potential readership.  One possibility was to declare that Newman devices merely make a vast increase in the amount of electrical power available from a given system, but still can't recharge a bigger battery from a smaller battery or anything.

Semi-Intelligent computers:

While not bestowing "sentience" in any sense, the ability to pack a vast knowledge base into a small space that allows super-high-speed access, combined with various adaptive-learning algorithms, have resulted in machines which, in their own narrow areas of expertise, can think as well as (or better than) any human specialist.

These semi-intelligent, or "SI", controllers are crucial to fighters (see below under "Standard military issue").  Not only must these combat vessels react to changing conditions in high delta-vee environments in a matter of milliseconds (if not microseconds), they also routinely accelerate at over a hundred g's, requiring "brain" hardware that can withstand such extreme force.  (No human or Centaurian can remain conscious beyond 9 or 10 g's.)

Interestingly, computer technology seems to be more readily graspable by humans than by Centaurians.  Only a tiny fraction of the human population had what it took to bring computing machinery into reality in the 20th century; among Centaurians, the traits necessary for this particular mental skill are practically nonexistent.  Prior to their capture of human satellites after first contact, semiconductor transistors had been produced in Alpha-Centaurian laboratories only, and the idea of using switching elements for manipulating information digitally had never been seriously pursued.  Alpha Centauri is continually playing catch-up with Sol in the computer department.

Hibernation chambers:

Euphemistically called "coffins" by humans due to their resemblance to burial caskets, these low-temperature pods reduce human biological activity to almost nil while still allowing the passenger to be revived later.  Human hibernation using this technology is officially called "submetabolic sleep."  Various inhaled and insinuative gasses are used to preserve the living tissues; the mixture must be varied slightly for first-time hibernators.

Magnetic focusers:

The second major technology, besides QC&C, that humans stole from the Centaurians after Second Contact.  A magnetic focuser allows a magnetic field to be focused so that all its field lines loop out in one direction.  Focusing is laserlike; spreading with distance isn't an issue, although diffraction still occurs so the range isn't infinite.  Until the onset of the Pentagon War, a magnetic focuser could only operate for a quick jolt; Sol and Alpha Centauri independently discovered how to make it operate continuously, and developed it in two different directions (the Directional Screen in Sol's case; the Liquid Metal Gun's guidance and course-correction system in Alpha Centauri's case).  Forms the basis for magnetic snares, Zelta Dee's Directional Screen, the guidance system on Alpha Centauri's liquid metal gun, and the ability for a slug launcher to keep accelerating its cargo past the end of its barrel.

Mass drivers:

Also know as electromagnetic launchers, slug launchers, or "railguns", these super-cannons can fire unguided projectiles at the relativistic speeds needed for spacecraft-to-spacecraft combat.  A typical muzzle velocity is 10 permil (1% of c), or 3000 km/sec.  A 1 kg slug fired at this velocity would have a kinetic energy of 4.5 trillion joules, which is slightly more than 1 kiloton of TNT, or the energy released from running 7 grams of protium through two-stage QC&C fusion.  If early 21st century EDLCs ("supercapacitors") were used to deliver this amount of energy to the launcher, they would have to mass at least 15 thousand tonnes; clearly, the capacitor technology that exists at the time of the Pentagon War far exceeds this meager energy density.

Most spacecraft only have enough room for a launch tube that's 10 meters long or so.  If the entire 10 permil muzzle velocity were imparted to the slug along such a short length, the slug would have to undergo an acceleration of 45 billion g for a little under 7 microseconds.  Instead, the impetus is provided by a magnetic focuser, whose pusher beam extends several kilometers past the end of the barrel.  A 10 kilometer magnetic-beam launch to 10 permil would involve a much more moderate average acceleration of 45 million g, and last a hair over 20 milliseconds.

Launching guided projectiles at these accelerations is impossible.  There's nothing you could build a guidance mechanism out of that would survive a multimegagee force like this.  This means the "message missiles" launched toward one's home hyper hole in an enemy system, which guide themselves toward the hole and transmit their message as soon as they're through it, cannot be launched at such high speeds.  They must carry their own drive mechanism with them so that they can accelerate — smoothly — to the relativistic speeds necessary to reach their transmit point quickly.  They'd be limited to the same load factors as unmanned Fighter craft, i.e. about 100g.  This, of course, makes them vulnerable targets during their initial slow-moving phase.

Magnetic snares:

Using a magnetic focuser as a simple "magnetic beam" which can pull on a ferromagnetic object from quite a distance away.  It can only apply a radial force, either pulling or pushing, never a lateral force.  Since continuous magnetic focusing technology was not available until the start of the Pentagon War, a magnetic snare could only impart a quick yank or shove to its target, making it impractical for docking maneuvers.

Gate Guards:

These are military space stations built into an asteroid, stationed next to the linked Hyper Holes in each system.  In peacetime, they double as customs inspection stations, emergency outposts, etc.  The guts of each gate guard are built underground, relying on the rocky mass of the asteroid for protection from attack.  Each Gate Guard is unique, depending on what asteroid was available to construct it out of; they can be over a hundred kilometers in diameter.

Needless to say, such a massive chunk of rock could not have been towed into place on a brachistochrone trajectory.  Instead, a suitable candidate was nudged into an orbit that would eventually bring it to the Hyper Hole it was needed at, then nudged again to match the Hyper Hole's own orbit.  Construction took place while the asteroid was en route.  Each Gate Guard has station-keeping thrusters on it to keep it in position near the Hyper Hole it's guarding; these thrusters are QC&C reactors that would qualify as the main engine on any normal-sized spacecraft.

Once the War began, it was quickly discovered that a fast-moving intruder stood a chance of zipping past a Gate Guard untouched.  To combat this, each nation began building "Second Guards" — Gate Guard installations positioned a couple thousand kilometers away from either side of the Hole.  Since Hyper Holes are basically flat, an intruder has to have a velocity vector almost perpendicular to the hole's face, so there is a very limited arc of possible positions that a fast intruder can move to once it's through the Hole.  Second Guards are stationed in the dead-center of that path.  Note that Sol had the problem of having its Hyper Holes on long trans-Jupiter orbits, so it took years to orbit its Second Guard asteroids into position; in the meanwhile, all they could plug the gap with were fighters.

Antiproton bombs:

The terror of the phased antimatter bomb has not eclipsed the need for good old-fashioned "conventional" antimatter weapons.  Antiprotons are over 2000 times as massive as positrons, and can be stored in a magnetic bottle with just as much ease, making them ideal for use in both warheads of large-scale destruction and supercompact one-megaton bombs.  Their use against planetary targets en masse is only slightly less distasteful to international politics as is the antiplanetary use of hyper bombs.

Meteorite bombs:

Also called "asteroid bombs" or "surface renders", these are magnetic bottles filled with antiprotons encased in big rocks.  Haul them over to the planet you want to attack and then de-orbit them so that they land on the military base (or city) of your choosing.  Like real meteor strikes, these rocks will plow deeply into the ground before lithobraking to a stop.  Unlike ordinary meteor strikes, the force of the impact will destroy the magnetic bottle inside the rock, releasing all the antiprotons to react after the rock has plowed some distance down into the ground.  Depending on the size of the encased warhead, the surface destruction of said rock can be multiplied by a factor of ten, a hundred, or even a thousand.  The surface waves will tend to do much more structural damage than an ordinary nuclear or antimatter aerial burst would.  One meteorite bomb can utterly annihilate even the sturdiest and most deeply buried of ground installations.  However, the radius of destruction is much smaller than that of an aerially detonated antiproton bomb, so they tend to be used more selectively against single, hardened targets than against large areas.

Meteorite bombs are not to be confused with "bunker buster" bombs designed to take out underground installations.  Meteorite bombs are designed to detonate only after penetrating through many, many, many meters of rock and dirt, thereby going off under what it is their users intend to destroy.

Antiproton beams:

The ultimate charged particle beam weapons.  They have a devastating effect on anything they hit.  Their only drawback is cost: the craft firing such a weapon must either carry all the antiprotons with it that it will fire, or be able to manufacture antiprotons as it needs them.  In either case, the total long-term energy consumption will be enormous.  They are used on special missions and are not standard military issue.

Standard military issue:

Proton beams, electron beams, guided missiles (with or without mass driver assistance), gamma ray lasers, ball bearing shotguns and sand blasters, the Solar system's Radiation Gun.  Sirius' Acid Gum Gun to corrode reflective armor into nonreflectiveness.  Magnetic plasma deflection fields for defense against charged particle beams and explosives, which may be augmented with short-range ultraviolet lasers to ionize monatomic hydrogen on interstellar voyages (if the spacecraft is capable of interstellar travel).  Alpha Centauri's Liquid Metal Gun.  Long-range radar.  Various antiradar countermeasures not unknown in this century.  Many low-powered weapons may be linked together in a point-defense system for use against incoming missiles or other nearby, small targets.

Fighters and Deployers: The usual military spacecraft is alternately called a fighter deployer, a carrier, and/or a mobile base.  It is a QC&C powered, manned vessel that tows 3-6 smaller unmanned vessels, called fighters.  (Do not be deceived by the name.  These "fighters" have nothing in common with fighter aircraft of the 20th century.  They are quite large, heavily armored/screened, and are not restricted to weaponry pointing in one direction only.)  One fighter is typically a cylinder 60 meters across by 200 or so meters long, with a mass of about 100,000 tonnes including all ordnance but not including its fuel.  Fully fuelled with protium and deuterium, a fighter weighs in at 270,000 tonnes (i.e. it has a mass ratio of e, giving it a delta-v budget equal to its exhaust velocity).  This means that a 4-fighter Deployer, carrying all 4 of its fighters fully fuelled and a full load of its own deuterium fuel, will have a total mass of about four million tonnes.  This means that to sustain 1g of thrust, a fully loaded fighter carrier will have to put one-and-a-fifth tonnes of deuterium through QC&C fusion per second.

A deployer's fighter complement is called, as you might expect, its squadron.  Fighters are semi-intelligent in their own right, capable of extremely complex tactics, strategic decision making, coordinating its actions with other fighters in the same squadron, and following orders the way a military pilot would.

The primary function of the fighter deployer is as a repair and resupply station for its fighters.  A fighter may burn a substantial fuel load and discharge an enormous amount of destructive force in a single engagement; it cannot afford to carry large stockpiles of protium and deuterium, or ammunition, due to the added weight.  Since fighters use protium-deuterium hot fusion engines that can be throttled up in excess of 100g, but deployers cannot exceed the physiological g limits of their crews, a deployer is considerably less maneuverable than a fighter.  It makes up for this deficiency by deploying its fighters a good distance away from the action, and by being armed and armored to the teeth.

Personal weaponry includes all the good old-fashioned (but messy) weaponry available at the end of the 20th century, plus: stundart pistols tailored for human or Centaurian physiology, a kevlar-like high-temperature plastic for body armor, ...

Whipple armor: A multi-layered steel-vacuum sandwich, similar to a modern Whipple shield but with more (and progressively thicker) layers.  It's designed to turn an impacting hypervelocity projectile into a progressively thinner and thinner cloud of plasma, until it's too weak to penetrate the inner layer(s).  The outermost layer is often made reflective to repel attacks by lasers.

Missiles: Missiles are small, unintelligent spacecraft designed to ram their target.  The bulk of their mass consists of protium and deuterium fuel for their tiny 100g hot-fusion engine.  They're usually shaped like long, narrow cylinders so that they can fit in missile launch tubes.  The missile launch tubes themselves are very weak mass drivers, which throw their cargoes away from the launching spacecraft at only a few kilometers per second.  This isn't done to give a missile a hefty initial velocity — a few km/s is peanuts compared with the missile's total dalta-v budget — it's done to put some distance between the missile and the launcher before the missile lights off its (rather destructive) engine.  Missiles can also be deployed without a launch tube, e.g. connected to hard points on the outermost layer of the spacecraft's whipple armor as external ordnance, but care must be taken before starting such a missile's engine to ensure that it neither blasts the launching spacecraft with its exhaust nor rams into it.

Too small for an S.I., missiles rely on radar emitters and passive thermal sensors to home in on a single designated target, and they can be fooled by thermal decoys (flares/"chaff") dropped at the last moment.  The hot-fusion engine has a highly gimballed nozzle for thrust vectoring; in many shorter missiles, this is the only means of steering, while in most others, a thruster quad on the nose allows the missile to rotate more rapidly.  Extremely rapid rotation is absolutely essential; a missile needs to point its thrust vector exactly where it's needed at an instant's notice, because its target will probably be undergoing unpredictable evasive maneuvers, particularly right before impact.  A missile designed to hit a hardenened target (a target with whipple armor like a fighter's) generally stays in one piece to minimize the area its impact will be spread over; a missile designed to shoot down an unarmored target in deep space often contains a small fragmentation warhead that blows the missile into many tiny pieces just before impact, to maximize the chance that at least one piece will score a hit.  Cruise missiles are larger, so that they can carry more fuel, and will accept encrypted orders from the launching spacecraft in mid-flight to change targets or abort (assuming the order arrives in time with the light-speed delay).

Drones: Both fighters and their deployers may also carry extremely small remotely-controlled unintelligent spacecraft called drones.  A drone resembles an EVA pod in 2001: A Space Odyssey or the escape pod seen at the beginning of Star Wars; it's a small unmanned spacecraft similar to a missile that carries a single secondary-caliber spacecraft-to-spacecraft direct fire weapon — a high-energy laser, a proton beam, even an electromagnetically launched missile or two of its own.  Like a missile, a drone has a small proton-deuterium hot-fusion engine.  Not only is a drone too cheap for its own SI Controller, it's too small for a useful radar emitter; a nearby fighter or manned spacecraft must provide it with weapon locks, and must pass along any maneuvering instructions more complicated than "home in on target."  Kinetic-kill drones aren't even reusable; they're basically a one-use electromagnetic gun with an engine.  The gun destroys itself on firing, and the recoil does so much damage to the engine that it's cheaper just to scrap it and buy a new one than it is to repair; in fact, the remains of the spent drone will be sent flying backwards nearly as fast as the slug is sent flying forwards!

Ascenders and Atmospheric Descent Pods: If an offensive campaign gets to the ground assault phase, victory is all but assured.  Any orbital defenses will have been taken out first (including the gate-guard sized space stations protecting any important planet), then any ground-based orbital strike installations and air/spaceports capable of launching orbital strike vehicles; then, any military targets exposed to the sky can be picked off at leisure from orbit.  Only after the enemy's military installations have been whittled down to next-to-nothing and their means of communications severed or interfered with as much as possible (a deaf enemy is a confused enemy, and a confused enemy is a vulnerable, low-morale enemy), will troops be landed on the surface.  The least expensive means of landing troops is an atmospheric descent pod (essentially a large Mercury spacecraft) — this requires a substantial atmosphere and cannot re-ascend once it has landed.  For hit-and-run raids, or for temporary troops, an ascender can be used.  These fusion powered aerospace craft are hardly taller than an Apollo spacecraft and have enough fuel to land, ascend to orbit at 9 g's, and even attain an interplanetary trajectory if necessary.  An ascender's nosecone is plated in nonablative Heat Bolide™ (similar to Space Shuttle tile material but not nearly as expensive), allowing it to be used for re-entry aerobraking as well as hypersonic ascent.

Typical starship mission profile

The typical starship is a Bussard fusion scramjet.  It scoops up hydrogen ions (mostly protium with a teeny weeny little bit of deuterium mixed in) from the interstellar medium, and fuses them into helium using a two-stage "at speed" QC&C engine.  The empty mass of such a spacecraft is typically 1000 tonnes, and the scoop field extends out to about a 4500 kilometer radius (about 63 trillion square meters in area).  We assume the interstellar medium in the local fluff has a density of roughly 50 hydrogen ions (plus another 50 atoms of non-ionized hydrogen) per liter.  Due to the abyssmal performance of a Bussard collector at low speeds, they carry enough fuel to accelerate them at a full g until they reach 10 percent of the speed of light, by which time the collection field is scooping up ionized hydrogen rapidly enough to sustain 0.5g of acceleration.  (This is roughly 1000 tonnes of protium.)

For the first phase of the trip, the starship is accelerating at a steady 1.0g from a dead stop to 0.1c.  It will be using its own fuel exclusively at first, and slowly ramp up the contribution from the scramjet until the scooped-up material accounts for half the total thrust.  The time it takes the spacecraft to accelerate at a constant acceleration a from a dead stop to a final velocity v is:

t = (v/a) / sqrt (1 - v2/c2)
This takes 0.097 years, and covers 0.00489 light-years.

For the second phase of the trip, the starship switches over entirely to its scramscoop for thrust.  The acceleration drops to 0.5g, then ramps up from 0.5g to 1.0g as its speed increases from 0.1c to 0.2c.  Determining the spacecraft's velocity at an arbitrary time t during this phase, even before relativity is taken into account, requires solving a differential equation; the pre-relativity solution works out to:

v = v0et/r
... where r is the ratio of current speed to acceleration.  In the local fluff with a 4472 km radius scoop, perfect proton fusion will produce 166.7 Newtons of thrust for every km/s the scramjet is travelling at.  Thus, for a 1000 tonne fusion scramjet, r works out to 6,000,000 seconds.  It takes 0.131787 years (before taking relativity into account) of burning all incoming material to double the spacecraft's speed.  This phase covers 0.038 light-years.

For the third phase of the trip, the starship accelerates at a steady 1.0g from 0.2c until it reaches the half-way point to its destination.  Relativity will be significant during this phase.  The rest-time it takes to cross a distance d from the end of the second phase to the midpoint of the trip, at a steady acceleration a from the starship's frame of reference, assuming an initial velocity at the end of the second phase that gives you a gamma of γ0, is:

t = c/a * (sqrt ((a*d/c2 + γ0)2-1) - sqrt(γ02-1))
(If the third phase of the trip begins at a speed of 0.2c, γ0 = 1.0206.)

For the fourth phase of the trip, the starship de-tunes its scoop field so as to cause drag, and scoops the interstellar medium into its fuel tanks to replenish them.  In the spacecraft's reference frame, it isn't merely deflecting the oncoming material backward, it's actually braking it to a halt inside its fuel tanks; this means that using the onrushing interstellar hydrogen to refuel in flight is going to generate a lot of heat.  There will have to be some kind of heat radiating system on board.  In the case of a conventional Bussard scramjet, the fuel tanks are external mylar balloons, and so the outer walls of the tanks themselves can serve as heat radiators (assuming enough convolutions are added to their design).  Assuming a 4472 km radius scoop, the maximum amount of drag braking force available at any velocity v, before adjusting for relativity, is 450,000,000 Newtons * (v/c)2.  Using drag braking alone, the starship will be able to sustain a 1.0g deceleration all the way down to 0.21c or so, by which point the starship's fuel tanks will have been completely filled with 1000 tonnes of fuel.  Since you're sustaining 1.0g of deceleration, the rate at which you'll refill your fuel tanks is inversely proportional to your velocity; at very high speeds, to keep the braking force down to 1.0g, you'll have to either let some of the incoming material pass right on through, or shrink the radius of the collection field.

For the fifth phase of the trip, the starship must burn some of the scooped-up hydrogen and jet it forward as exhaust, in order to sustain 1.0g of deceleration.  The amount grows until it's burning all incoming hydrogen at 0.16c.  This phase lasts 0.0475 years and covers 0.0088 light-years.

For the sixth and final phase of the trip, the starship burns fuel from its onboard tanks — in addition to the interstellar material being scooped, braked, and burned — to keep the braking force at a steady 1.0g.  This would pretty much use up all the remaining fuel.  This phase lasts 0.152 years and covers the final 0.0122 light-years.

During the very last days of that final phase, depending on your destination, you might get a very big boost in the amount of braking you'll get from your environment — in the form of your target star system's stellar wind.  If it's strong enough, the last 1 or 2 percent of the speed of light can be bled off without expending an ounce of your own fuel, and even allow you to replenish a little of the fuel in your once-again-empty tanks.  The amount of fuel you have to expend during the first and last few days of the journey depends severely on the extent of the asterosphere within that star system.  Outbound from the sun, you don't reach the heliopause for an impressive 110 A.U., or about 0.0017 light-years; but outbound from a dim red dwarf, you'll run into the asteropause far earlier.

For Arnold and Jerry's scramjet, they accelerate at 2.0g and carry enough fuel (roughly 5x their empty weight) that they can sustain this until 0.2c before switching over entirely to ram-generated thrust.  They go through the same phases as above, but the cutoff speeds and durations/distances covered by each phase change.  Phase 1 covers 0-0.2c, lasts 0.099 years, and crosses 0.01 light-years.  Phase 2 covers 0.2-0.4c, lasts 0.131787 years as before, and crosses 0.076 light-years.  Phase 3 starts at 0.4c0 = 1.091), and covers d = half-way trip distance minus 0.0855 light-years — for an 8.554 light-year trip from Sol to UV Ceti, phase 3 will last 4.4811 years.  Phase 5 starts at 0.52c, continues down to 0.46c, lasts 0.0285 years, and covers 0.014 light-years.  Phase 6 lasts 0.219 years and covers the remaining 0.0503 light-years.

Now, you may be asking yourself: Self, how does the "collection field" of a scramjet's scoop work?  How does it reach out to a forty-five hundred kilometer radius, grab non-ionized hydrogen, and draw it in to its voracious maw?  Well, the usual way proposed by most folk is to make sure that the hydrogen isn't non-ionized, and then just use a plain old magnetic field or electrostatic field to draw it in.  In order to do that, you'd need to hit every hydrogen atom with enough energy to ionize it.  The ionization energy of a hydrogen atom is 13.6 eV; this corresponds to an ultraviolet photon of wavelength 91.16 nm (frequency 3.289 Petahertz).  So, if you were to sweep the region with a 911.6 Ångstrom ultraviolet laser at sufficient beam wattage, you could ionize all incoming hydrogen.  The big question is, how much beam wattage would you need?  At 10% of the speed of light, you'd need to ionize 150 grams (i.e. 150 moles) of hydrogen per second.  That works out to 196.7 megawatts.  But that assumes that every photon your laser emits strikes a hydrogen atom within 4472 km.  That is only possible if you know the location of each hydrogen atom before you reach it, which you won't.  You're going to have to waste a lot more power than that, simply sweeping the forward space in the hope of catching all the hydrogen atoms.

How much more power?  Well, let's assume that a photon has a "capture radius" equal to its wavelength — that is, if one of our UV photons passes within 91.16 nm of a hydrogen atom, that atom will absorb the photon and ionize.  (This may be an incorrect assumption; according to the hydrogen link on this page, the photoionization cross-section of a hydrogen atom at 13.6 eV is only on the order of 1 Megabarn, or 10-4 square nm.)  A corridor of interstellar space 1 square cm in cross-section and 30,000 km in length will contain 3 x 108 hydrogen atoms, giving it a total capture cross-section of 7.8 x 1012 square nm.  At 1014 square nm per square cm, nearly a tenth of the whole area has a hydrogen atom somewhere in it that will absorb a photon that passes through that point.  So, we might be able to get by with an ultraviolet laser beam output of only 2 gigawatts.

Of course, lasers aren't 100% efficient, so the laser's power-draw requirements will be several times higher than its beam-power output.  (And the power that doesn't go into the beam, due to the laser's inefficiency?  That's gonna be heat.  You'll need radiators, or a way to dump that heat into the exhaust stream.)

Since the power released from the fusion of 150 grams of protium into helium per second is 94.5 terawatts, we might be able to afford the energy drain caused by this sweeping UV laser.  It all depends on how efficient our laser is.

The good news is, all this may be unnecessary.  About half of the hydrogen in the Local Fluff — and nearly all the hydrogen in the broader and thinner Local Bubble — is already ionized.  Phototonization would only be necessary directly ahead of the physical structure of the starship, to ensure that it doesn't smack into any material that doesn't get scooped up.

Electrostatic scoops: the proton vs. protium replenishment problem

The interstellar medium in the Local Fluff consists of about 50% ionized hydrogen (protons) and 50% non-ionized hydrogen (protium).  Protons are positively charged, and so can be drawn in magnetically or electrostatically; protium is not, and cannot so be drawn in.  A starship will have a forward-facing UV laser that constantly sweeps the area immediately in front of the spacecraft, to turn all protium directly in front of the 'craft into protons, thus allowing them to be scooped in instead of slamming against the forward hull.

This means the stuff a starship scoops up will be positively-charged hydrogen ions, instead of neutral hydrogen.  Theoretically, a magnetic scoop could suck up the free electrons just as easily as it could suck up the hydrogen ions, and could in fact inhale both at the same time; but with an electrostatic scoop, you can only suck up one or the other.  There are two problems with this, a minor one and a major one:

(1) In a scramjet, the scooped material is run through QC&C nuclear fusion.  The result of the nuclear fusion of two protons is a deuteron and a positron.  If none of the incoming material is electrons, you won't have any electrons to annihilate your positron with.  This means you must dump your positrons directly out of the exhaust.  This could theoretically make the trip much more perilous for the next starship that follows your path through space, except that by that time the positrons will have had time to mix with the electrons that are naturally present in all that ionized hydrogen out there.  You might get a few gamma ray flashes in your wake, but this is a minor problem.

(2) A more serious problem comes when it's time to undergo braking.  You'd like to be able to use the braking phase to replenish the hydrogen (protium) in your starship's fuel tanks, which you had to expend to get it up to speed in the first place.  But you're not scooping up protium, you're scooping up protons.  If you tried to store those, you would very quickly pick up an electric charge imbalance, which is a very bad thing.  You would need to alternate the electric charge on the scoop from time to time, to attract electrons instead of protons; or you would need to be able to scoop up neutral hydrogen instead of ionized hydrogen, which only Poul Anderson can get away with; or you would need to forego the whole process of replenishing your fuel tanks while braking and instead carry enough fuel for both the outbound acceleration phase and the final braking phase, which doubles your rocket-based delta-v requirements.  Another possible solution to this dilemma is to ground your fuel tank, so that the charge imbalance ends up spread out over the outer hull.  Then as the starship accumulated a net positive charge, electrons from nearby space (the ones that were bound to the ionized hydrogen before it became ionized) would naturally be attracted to the hull, and would neutralize the ions in its fuel tank on their own.  This might work with a starship with a magnetic scoop, but a starship with an electrostatic scoop (like Mercurand) would have trouble overcoming the net negative charge of its drogue-wire.

An analysis of the feasibility of Alan Bond's RAIR

The Ram-Augmented Interstellar Rocket, or RAIR, was once considered as a promising compromise between the true Bussard ramscoop and a pure rocket.  In theory, you could scoop up the interstellar medium and use it as extra reaction mass for your fuel combustion to push against.

However, there are two problems.

First, the interstellar medium is exceptionally thin.  In the "local fluff" in which the sun and a few neighboring stars are embedded, the density of the interstellar medium is only about 1 atom of hydrogen for every 10 cubic centimeters.  (Outside the local fluff it's about half that.)  This means that if your starship had a ridiculously huge 1000 km radius scooping field, at 10% of the speed of light you'd only be scooping up 15 grams of hydrogen per second.  Even a modest spacecraft would have to weigh in at at least 100 tonnes empty to carry anything even remotely interesting, and that's the empty mass, before the mass of its unexpended fuel is added in.  Accelerating a 100 tonne fusion rocket at 1 g requires burning 28 grams of protons.  The extra 15 grams you're scooping in at 0.1 c aren't going to provide much to push against.

Secondly, the reaction mass isn't standing still when you scoop it in.  If you're moving at 0.1 c, those 15 grams of interstellar medium are zipping down your gullet at 30,000 kilometers per second.

This second point is actually the most significant.  Remember, dumping the energy you get from burning your fuel into the exhaust increases its kinetic energy — but it's the change in the exhaust's momentum that drives your starship forward.  Adding a given amount of energy to 15 grams of matter that are already going at 0.1 c is going to give you a much smaller momentum change than adding that same amount of energy to 15 grams of matter that are standing still (relative to you).

How much smaller?  Well, when increasing any object's velocity, the increase in kinetic energy is:

ΔKE = ½m (v0 + Δv)2 – ½mv02

... where m is the mass of the object, v0 is its initial velocity, and Δv is the increase in its velocity.  The spent fuel has a v0 of zero; the incoming ram-scooped material has a v0 equal to the speed of your spacecraft.

So, for comparison, to give 15 grams of spent fuel a nudge of 1000 km/sec would take:

ΔKE = ½(0.015 kg) (0 + 1,000,000 m/s)2 – ½(0.015 kg)(0)2
  = ½(0.015 kg) (1,000,000 m/s)2
  = 7,500,000,000 Joules

... and to give 15 grams of ram-scooped material travelling at 0.1 c (30,000 km/s) the same 1000 km/sec nudge would take:

ΔKE = ½(0.015 kg) (30,000,000 m/s + 1,000,000 m/s)2 – ½(0.015 kg)(30,000,000 m/s)2
  = 7,207,500,000,000 Joules – 6,750,000,000,000 Joules
  = 457,500,000,000 Joules

... or 61 times more energy.

However, it's possible to use some of the kinetic energy of the oncoming interstellar medium to your advantage.  You can "mix" it with your fusion reactor's own exhaust stream, so that some of its momentum is transferred to your fusion fuel products.

Then, you're not talking about "dumping" the energy from your fusion burn into the ram-scooped matter stream anymore.  You're talking about "pooling" the kinetic energy of the oncoming material with the energy released from fusion, and applying that combined energy total to the entire combined mass of your exhaust.

Say you're going 0.2 c.  At that rate, you're taking in 30 grams of interstellar medium per second.  Normally, if your 100 tonne spacecraft were a pure rocket, burning 28 grams of onboard protons over the course of one second would produce an impulse of 980,000 kg m/s, giving you an acceleration of 1.0g.  But if we combine this with the 30 grams of inert mass we've just scopped up, we get:

Initial momentum of collected material = 60,000,000 m/s * 0.03 kg = 1,800,000 kg m/s
Kinetic energy of collected material = ½ * 0.03 kg * (60,000,000 m/s)2 = 5.4 x 1013 Joules
Energy released from fusion of 0.028 kg of fuel = 1.764 x 1013 Joules
Total energy E available to put into exhaust = 5.4 x 1013 J + 1.764 x 1013 J = 7.164 x 1013 Joules
Exhaust velocity = SQRT (2E / (0.03 kg + 0.028 kg)) = 49,702,564 m/s
Momentum of exhaust = 49,702,564 m/s * 0.058 kg = 2,883,000 kg m/s
NET momentum transferred to starship = 2,883,000 kg m/s – 1,800,000 kg m/s = 1,083,000 kg m/s

... which would impart an acceleration of 1.105 g to the spacecraft.

This advantage dwindles, however, the more we increase the spacecraft's mass.  If we assume that 100 tonnes is the empty weight of our starship, and at 0.2 c we're still carrying enough fuel for another ~0.1 c worth of acceleration (again assuming near-perfect nuclear fusion with a 0.1c exhaust velocity), that means our spacecraft currently has a mass of e times its empty weight, or 272 tonnes.  It takes about 75 grams of proton fusion to accelerate this much mass at 1.0 g in a pure rocket design.  If you add 30 grams of RAIR material to this, your new optimally-mixed acceleration works out to only 1.07 g.

But now suppose that instead of using a "normal" magnetic scoop, we use a much more efficient scoop, such as the Matloff and Fennelly electrostatic scoop-line or the similar design that I'm calling "the Drogue" on Mercurand.  Let's say that at 0.2 c, this scoop can gather up a whopping 100 kg of interstellar medium per second.  Then, for a 100 tonne spacecraft, we get:

Initial momentum of collected material = 60,000,000 m/s * 100 kg = 6,000,000,000 kg m/s
Kinetic energy of collected material = ½ * 100 kg * (60,000,000 m/s)2 = 1.8 x 1017 Joules
Energy released from fusion of 0.028 kg of fuel = 1.764 x 1013 Joules
Total energy E available to put into exhaust = 1.8 x 1017 J + 1.764 x 1013 J = 1.8001764 x 1017 Joules
Exhaust velocity = SQRT (2E / (100 kg + 0.028 kg)) = 59,994,541 m/s
Momentum of exhaust = 59,994,541 m/s * 100.028 kg = 6,001,133,975 kg m/s
NET momentum transferred to starship = 6,001,133,975 kg m/s – 6,000,000,000 kg m/s = 1,133,975 kg m/s

... which would impart an acceleration of 1.157 g to the spacecraft.  Bleah.  That's hardly what I'd call an improvement.

Mercurand's antimatter engine:

As originally designed, Mercurand carried 100 tonnes of antiprotium, and the rest of the spacecraft massed an additional 100 tonnes, including 1 tonne of normal protium it carried for its boost phase.

When burning its internal hydrogen supply, 1 antiprotium atom is annihilated with 1 protium atom, and the resulting thermal energy is used to accelerate an additional quantity of protium as exhaust.  Each kg of protium and antiprotium annihilated yields 1.8 x 1017 J of kinetic energy.  Let's see how much momentum this will impart to Mercurand when applied to different masses of propellant.  Since Mercurand only carries 1 tonne of koinohydrogen, we can assume its mass will stay constant at nearly 200,000 kg for the duration of this non-scooping boost phase.  This 1.8 x 1017 J of kinetic energy will have to be split between the exhaust and Mercurand in such a way that the net change in the momentum of both bodies is 0:

Velocities for ΔKE = 1.8 x 1017 J, 200 tonne spacecraft
Propellant massExhaust velocity Spacecraft Δv
1 kg γ = 3  (0.9428c) 4240 m/s
10 kg 189,732,000 m/s 9486.6 m/s
100 kg 59,985,000 m/s 29,992 m/s
1,000 kg 18,920,000 m/s 94,632 m/s
1,000,000 kg 245,000 m/s 1,225,000 m/s
1,000,000,000 kg 268 m/s 1,341,510 m/s
1,000,000,000,000 kg 0.268 m/s 1,341,640 m/s
Note: Other than the first entry, none of these velocities are adjusted for special relativity

So if we can only afford to expend 1 kg of our internal protium supply as propellant per kg each of protium and antiprotium annihilated, we only get 4240 m/s of delta-v.  That's not very much, is it?  Expend all 1000 kg of protium, and you've only got 2120 km/s of delta-v, barely enough to accelerate you to 7 permil.  You'll need at least 10 permil, preferably 100 permil, to sweep up the interstellar medium at a decent rate, and that doesn't even count the 4000 km/s they'll need to expend to accelerate and decelerate across the 200 million km gap between the Sirius/HC and Sirius/Sol hyper holes.

If we allow Mercurand to carry 100 tonnes of protium instead of just 1 tonne, that changes the picture dramatically.  Now we can afford to dump 100 kg of propellant into the exhaust for every 1 kg of protium and 1 kg of antiprotium annihilated.  With a fully loaded mass of 300 tonnes, an "empty weight" after expending all propellant (but not all antiprotium) of 199 tonnes, an an exhaust velocity of 60,000 km/s, that gives us a total delta-v budget of 24,630 km/s, or 82 permil.  Even if we assume that the above table is bogus, and that all the kinetic energy from the annihilation can be funneled completely into the exhaust, that still gives us an exhaust velocity of 60,000 km/s, because the spacecraft is so much more massive than the exhaust fraction that the difference is too tiny to matter.

This is reasonable.  Mercurand, therefore, has an empty mass of 100 tonnes, and carries 100 tonnes of whiteflake antiprotium in one tank and 100 tonnes of cryogenic protium in another tank, giving it a total "takeoff weight" of 300 tonnes.

But let's see what the optimum would be.  We agree to limit the amount of antiprotium we annihilate to 1 tonne during all non-scoop operations.  Annihilating this with exactly 1 tonne of protium yields 1.79751 x 1020 J of total kinetic energy.  Because the amount of kinetic energy is so high, and the amount of "dead weight" propellant it's applied to is so small, we can't just use ½mv2 to calculate the exhaust velocity; it will be necessary to adjust for relativity.  The relativistic kinetic energy of rest-mass m is of course (γ−1)mc2, which means that γ = (1.79751 x 1020 J / mc2) + 1 = (2000 kg / m) + 1 = 1 / sqrt(1 − v2/c2).

If we have the relativistic exhaust velocity, we can use the regular Tsiolkovsky rocket equation.  Although 2 tonnes of the material that is expended is annihilated and is not propellant, the mass-energy from that annihilation is used to accelerate the propellant to relativistic speeds.  Thus the propellant's increased relativistic momentum would make it behave as though it were actually 2 tonnes heavier.  So, if we vary how much "dead weight" propellant we allow Mercurand to carry, in the form of protium that doesn't get annihilated, what does Mercurand's total non-scoop delta-v budget work out to?

Delta-v budgets for 199 tonne "empty" spacecraft
Starting massPropellant mass Unadjusted exhaust velocityRelativistic exhaust velocity Total Δv
202 tonnes 1 tonne 599,585 km/s 282,647 km/s 4,229 km/s
211 tonnes 10 tonnes 189,605 km/s 165,717 km/s 9,703 km/s
301 tonnes 100 tonnes 59,958 km/s 59,076 km/s 24,446 km/s
401 tonnes 200 tonnes 42,397 km/s 42,082 km/s 29,485 km/s
501 tonnes 300 tonnes 34,617 km/s 34,445 km/s 31,803 km/s
601 tonnes 400 tonnes 29,979 km/s 29,867 km/s 33,012 km/s
701 tonnes 500 tonnes 26,814 km/s 26,734 km/s 33,664 km/s
801 tonnes 600 tonnes 24,478 km/s 24,417 km/s 34,002 km/s
901 tonnes 700 tonnes 22,662 km/s 22,614 km/s 34,152 km/s
951 tonnes 750 tonnes 21,894 km/s 21,850 km/s 34,178 km/s
961 tonnes 760 tonnes 21,749 km/s 21,706 km/s 34,180 km/s
971 tonnes 770 tonnes 21,608 km/s 21,566 km/s 34,183 km/s
981 tonnes 780 tonnes 21,469 km/s 21,427 km/s 34,182 km/s
1,001 tonnes 800 tonnes 21,199 km/s 21,159 km/s 34,181 km/s
1,051 tonnes 850 tonnes 20,566 km/s 20,529 km/s 34,164 km/s
1,101 tonnes 900 tonnes 19,986 km/s 19,953 km/s 34,133 km/s
1,201 tonnes 1,000 tonnes 18,961 km/s 18,932 km/s 34,032 km/s
2,201 tonnes 2,000 tonnes 13,407 km/s 13,397 km/s 32,198 km/s

Note that there appears to be a "sweet spot" between the 971 and 981 tonne entries.  Adding more propellant past about that point actually reduces your total delta-v budget.  At the time of the Pentagon War, this optimal mass ratio — around 4.9 for a craft carrying about half a percent of its empty weight in antimatter — is known as the Heisenblatt-Sturnbridge ratio.  (Confusingly, the ~780-to-1 ratio of protium to antiprotium, which the engine will consume while producing its thrust at this optimal delta-v level, is also called the Heisenblatt-Sturnbridge ratio.)

Now . . . what about after Mercurand has expended all of its onboard propellant, and has to rely on Drogue-gathered interstellar ionized hydrogen both for annihilation material and reaction mass?

In chapter 9, they accelerate to 6-and-two-thirds permil in the Sirius system, then decelerate back down to 1 permil, then do a powered turn to hit the hyper hole bound for Sol space.  The powered turn consumes 1.57 permil of delta-v, so their total delta-v expended up through the end of the turn comes to 13.9 permil.  This leaves them with 68.1 permil of delta-v that they can use to accelerate to interstellar speeds before running out of propellant.  This ignores the potential additional propellant they could pick up by deploying the Drogue during this "runway" phase, but let's assume a worst-case scenario and assume that they manage to accelerate to 69 permil at the point their koinohydrogen runs out.

So, at 69 permil, how much interstellar ionized hydrogen will they be sweeping up per second, within the local fluff?

We can assume that the Drogue performs as optimally as Matloff and Fennelly suggest it might, with an effective gathering radius of 100 000 kilometers.  At 0.069c, such a scoop would sweep out a volume of 6.5 x 1023 cubic meters, or 6.5 x 1026 liters.  At 50 hydrogen ions (protons) per liter, and 1.67 x 10-27 kg per proton, that works out to 54 kg of hydrogen ions per second that could theoretically be scooped up at this speed.

Let's assume we're not willing to annihilate more than 1/1000 of the incoming material, so that the rest is just deadweight reaction mass.  0.1% of 54 kg is 54 grams.  Annihilating 54 grams of matter with 54 grams of antimatter produces 9.7 x 1015 Joules of energy.  If we funnel all of that energy into the kinetic energy of the exhaust, operating from the (incorrect) assumption that we're accelerating it from a dead stop relative to the spacecraft (which we're not), the exhaust velocity will be about 18,900 km/s.  Throwing 54 kg aft at 18,900,000 m/s will increase Mercurand's forward velocity by 5100 km/s, or roughly half a million g.  Clearly, this is far more thrust than we need.

Now . . . what's their total delta-vee budget for chapters 14 and onward? I.e. for maneuvering in Limbo, and fighting the invading Sirians in HC space?

For the return trip, their hydrogen tank is full (100 tonnes), but their antihydrogen tank is half empty (only 50 tonnes). Worse, their drogue gets hopelessly tangled and has to be ejected. They will not be able to gather any interstellar hydrogen or stellar wind. They have to run entirely on what they have stored.

Let's assume they're willing to use all of their stored antihydrogen this time. They are in pretty desperate straits, after all. This brings us back to the first case we considered above: 1 kg propellant per kg each of protium and antiprotium annihilated. Their exhaust velocity will be γ = 3 (0.9429c). We need to convert that to its nonrelativistic equivalent for purposes of the Tsiolkovsky rocket equation. Since we're imparting 2 kg * c2 Joules of energy to each kg of propellant, assuming all of this energy gets turned into kinetic energy of the exhaust, we get an "effective exhaust velocity" (for purposes of the Tsiolkovsky equation) of exactly 2c (600,000 km/s). Initial mass of Mercurand is 250 tonnes, final (empty) mass of Mercurand on fuel exhaustion is 100 tonnes. Applying the Tsiolkovsky equation, we get:

Total Δv = 600,000 km/s * ln (250/100) = 549,774 km/s
... or about 1830 permil. Let's see how this synchs up with the relativistic Δv equation from Nyrath's "Slower than Light" webpage, which says that Δv = c * Tanh[(ve/c) * ln(R)]. Plugging the numbers in, we get:
Total Δv = 300,000 km/s * Tanh[0.9429 * ln (250/100)] = 209,489 km/s
... which is considerably lower than what we get from my equation. Note that the Δv that results from this equation is corrected for Relativity, and assumes a spacecraft starting with velocity 0 and spending all its propellant accelerating away (or toward) a fixed observer. If half of this Δv is used to speed up and the other half is used to slow down, the peak velocity in the middle will be higher than 0.5*Δv.

Still, even if it weren't, that's nearly 700 permil of delta-vee, more than enough for any maneuvering Mercurand might have to perform.

The battle in chapter 6

Let's try an initial separation, between Gellimand 3 and the Zelta fighters when the cruise missiles are launched, of 15,000,000 km.
Initial relative velocity: 4500 km/s closing.
Gellimand 3 accelerates at 1 km/s2 until its relative velocity is 6000 km/s closing.
This would cover 7,875,000 km, and last 1500 seconds = 25 minutes.

Covering the remaining 7,125,000 at 6000 km/s would take 1187.5 sec = 19.8 min. Let's say 20 minutes, for a nice round number. So that's a total of 45 minutes from the time the cruise missiles are launched to the time they reach Gellimand 3.

Zelta Cee will be decelerating for the same 25 minutes that Gellimand 3 was accelerating. Their closing speed will be a steady 4500 km/s during that time. When they switch off their engines, they will be 8,250,000 km apart, and closing at 4500 km/s.

Will Zelta Dee be able to match speeds in this short 8,250,000 km stretch? It's going from 4500 km/s to 0 at -1 km/s2. This will cover 10,125,000 km. So, NO, it will not be enough run-up room. They'll need another 2 million klicks or so.

We need to start the approach at 17 million km, not 15 million. Actually, to discourage Gellimand 3 from applying "just a touch" more acceleration and causing Zelta Dee to miss the rendezvous, let's start at 20 million km.

Initial separation: 20,000,000 km.
As before, initial relative velocity is 4500 km/s closing, and Gellimand 3 accelerates to 6000 km/s at 1 km/s2.
Again, this would cover 7,875,000 km, and last 1500 seconds = 25 minutes.

Covering the remaining 12,125,000 at 6000 km/s would take 2020.8s = 33.68 min. Let's say 34 minutes, for a nice round number. So that's a total of 59 minutes from the time the cruise missiles are launched to the time they reach Gellimand 3.

Zelta Cee will be decelerating for the same 25 minutes that Gellimand 3 was accelerating. Their closing speed will be a steady 4500 km/s during that time. When they switch off their engines, they will be 13,250,000 km apart, and closing at 4500 km/s. It will be 2944.4s = 49 minutes from this point that they will meet.

For story reasons, the time between the Zelta-Cee/Gellimand 3 closest pass and the point at which Zelta-Dee and Gellimand 3 encounter each other must be 40 minutes. So, the amount of time that elapses between the launch of the cruise missiles and the launch of Zelta-Aay and Zelta-Bee must be 7227 seconds = two hours and 27 seconds. At the end of this time, Gellimand 3's distance from Zelta must be 108 million klicks, give or take 45 thousand.

Now then ... what about the next encounter, between Gellimand 3 and the other two Zelta fighters? Zelta Aay and Zelta Bee both start out at station-keeping right next to Zelta.

Intruder's initial distance from Zelta: 108,000,000 km
Intruder's initial velocity: -4500 km/s
Defender's initial velocity: 0

Gellimand 3 burns its engine at full thrust, -1 km/s2, for 1500 seconds. Let's see what happens if the defender does the same, i.e. if the defender accelerates at 1 km/s2 to a speed of 5 permil:

Defender's position at engine shutdown:
½ * 1 * 15002 = 1,125,000 km.

Intruder's position at engine shutdown:
½ * (-1) * 15002 + (-4500) * 1500 + 108,000,000 = 100,125,000 km.

At some point in space d, the defender decelerates to match the intruder's velocity. Since relative velocity = 7500 km/s, the defender will have to decelerate at 1 km/s2 for 7500 s.

Defender's position after matching intruder's velocity:
½ * (-1) * 75002 + 1500 * 7500 + d = -16,875,000 km + d

So the point d will have to be at least 16,875,000 km, if the rendezvous is to occur at a non-negative distance from the starting line.

This means the defender will have to coast for 15,750,000 km at a mere 1500 km/s. This will take 10,500 seconds.

Intruder's FARTHEST POSSIBLE position at the start of the defender's velocity-matching burn:
(-6000) * 10,500 + 100,125,000 = 37,125,000 km

BUT, in the 7500 seconds it'll take for the defender to match velocity, the intruder will have moved 45,000,000 km!

So, a rendezvous-intercept will not be possible if the defender only accelerates to 5 permil. But what if the defender accelerates to 10 permil?

Defender's position at new initial engine shutdown:
½ * 1 * 30002 = 4,500,000 km.

Intruder's position at defender's new initial engine shutdown:
(-6000) * 1500 + 100,125,000 = 91,125,000 km

At some point in space d, the defender decelerates to match the intruder's velocity. SInce relative velocity = 9000 km/s, the defender will have to decelerate at 1 km/s2 for 9000 s.

Defender's position after matching intruder's velocity:
½ * (-1) * 90002 + 3000 * 9000 + d = -13,500,000 km + d

So the point d will have to be at least 13,500,000 km, if the rendezvous is to occur at a non-negative distance from the starting line.

This means the defender will have to coast for 9,000,000 km at 3000 km/s. This will only take 3000 seconds.

Intruder's FARTHEST POSSIBLE position at the start of the defender's velocity-matching burn:
(-6000) * 3000 + 91,125,000 = 73,125,000 km

In the 9000 seconds it'll take for the defender to match velocity, the intruder will have moved 54,000,000 km. This means the intercept could occur as much as 19,875,000 km away from the defender's starting line.

So a rendezvous-intercept IS possible, if the defender is willing to accelerate to 10 permil and then back-accelerate by a whopping 30 permil. This will run its fuel tanks completely dry, assuming a 40 permil delta-v budget, and leave it hurtling out of the Solar system at 20 permil.

Putting it all together:

Time vs. separation from Zelta, in the battle against Gellimand 3
Time (s) G3 (km) G3 (km/s) cm (km) cm (km/s) Z-C (km) Z-C (km/s) Z-D (km) Z-D (km/s) Z-A/B (km) Z-A/B (km/s)
0 378,876,000 -1500 0 0 0 0
1500 375,501,000 -3000 1,125,000 1500 1,125,000 1500
80250 139,251,000 -3000 119,249,500 1500 119,249,500 1500 119,249,500 1500
80317 139,050,000 -3000 119,350,000 1500 119,347,755 1433 119,347,755 1433
81750 133,724,255 -4443 121,499,500 1500 120,374,500 0 120,374,500 0
81817 133,425,000 -4500 121,600,000 1500 120,374,500 0 120,372,255 -67
83787 124,560,000 -4500 124,555,000 1500 120,374,500 0 118,299,815 -2037
84717 120,375,000 -4500 120,374,500 0 115,972,955 -2967
85950 114,826,500 -4500 111,554,500 -4200
87117 109,575,000 -4500 109,375,000 -4200
87477 107,955,000 -4500 0 0
87837 106,335,000 -4500 64,800 360
88197 104,650,200 -4860 259,200 720
89337 98,460,000 -6000 1,080,000 720
103828 11,514,000 -6000 11,513,520 720

Landmark times:

The battle in chapters 9 and 10

Mercurand doesn't want to end up reaching the Sirius/Sol hyper hole at velocity 0, but instead wants to reach it going one permil (300 km/s). Since the Sirius/Sol hyper hole is pointed at almost a right-angle from the line between it and the Sirius/HC hyper hole, Mercurand can't just fly straight toward the hole, slow down to 300 km/s, and then dive through. It would have to plot a course that put it far enough to one side of the Sirius/Sol hyper hole that it could follow a circular path into it.

Going 300 km/s with an acceleration of 0.02 km/s2, the circle it would follow would have a radius of 4,500,000 km. It would take 23,562 seconds to sweep out a 90 degree arc of this circle. Mercurand's speed would have to be down to 1 permil (300 km/s) at the start of this circular turn, which would occur after having travelled a grand total of 195,500,000 km in-system. (The angle at which Mercurand would have to fly, relative to the Sirius/HC-Sirius/Sol hyper hole line, is the arctangent of 4,500,000 over 195,500,000, or 1.32 degrees.) This puts Mercurand's turnaround/skew-flip point at 97,750,000 km, which would take exactly 85,000 seconds.

Of course, this assumes that they have to keep following this circular arc RIGHT up to the hyper hole's front doorstep, which doesn't give them a very wide margin of safety. It would be more sensible to pick a trajectory that lets them finish out the circle, and be on a direct course for the center of the hyper hole, when they're still a light-second (300 000 klicks) away from it, thereby giving them ample opportunity for last minute course refinement. (And also giving them the option of putting themselves on a ballistic collision course with the Gate Guard or near-side Second Guard, if they want to be spoilsports.) This means the angle at which Mercurand would have to fly would actually be the arctangent of 4,800,000 over 195,500,000, which is 1.41 degrees.

Now, what about the message missile's trajectory? It can't fly straight toward the hyper hole either. If it's not going to slow down, it needs enough TIME to be able to send its message through the hole with line-of-sight on Sol's Second Guard. That means it needs to come in nearly perpendicular to its surface. It will have to fly a curved path like Mercurand, only at a higher speed and with a 100g engine. This also means it has to hold enough delta-v in reserve to make this "terminal maneuver" against the hyper hole. When turning 90 degrees without changing speed, the delta-v requirement is always (π/2) times your speed. So, a message missile that has to hit a hyper hole facing 90 degrees off from its primary course has to hold not JUST its cruising speed, but π/2 TIMES its cruising speed, of delta-v in reserve. This limits their cruising speed to their delta-v budget / (π/2 + 1).

Message missiles have a total delta-v budget of 18,000 km/s, so the max. cruising speed for hitting a perpendicular hyper hole would be 7000 km/s. BUT, that's the max cruising speed RELATIVE TO ITS LAUNCH PLATFORM. In the case of Mercurand, it's already going 300 km/s when the missile is launched. If it accelerates 7000 km/s on top of this, it'll be going 7300 km/s when it starts its turn, which puts it 467 km/s over budget on its delta-v requirement. If it accelerates only 6700 km/s on top of this, it'll be going 7000 km/s when it starts its turn, but that will leave 300 km/s of unused delta-v left over and wasted. The missile could also decelerate BEFORE making the turn, so that it's not barreling toward the face of the hyper hole at its cruising speed. This also gives it more time to transmit its message to the Sol Gate Guard or Second Guard on the other side of the hole. If we elect to have it close with the hyper hole at a paltry 300 km/s, it'll take 472 km/s of delta-v to make the turn, and with a 100g engine the turning radius will be only 90,000 km. 18,000 minus 472 is 17,528, which is all the accelerating or braking we can do before the turn. Since v0 = 300 km/s, and final v must also be 300 km/s, we can accelerate by a maximum of half that (8764) to a cruising speed of 9064. This will of course take 8764 seconds. Braking from 9064 km/s to 300 km/s will likewise take 8764 seconds and cover 41,033,048 km, so it must begin 41,123,048 km before the hyper hole to allow for the 90,000 km radius turn at the end.

So, assuming our Sirian fighter accelerates for 600 seconds to a course that intercepts Mercurand's, and that the message missile is launched 2 hours before the fighter begins its acceleration, and that the message missile just happens to be travelling on a course that will intercept the fighter (cough cough), here's what we get (calculations assume the missile is on course straight for the hyper hole, not for a point 90,000 km to one side of it, but it's so close as to not make much difference):

Time vs. separation until fighter-Mercurand intercept
Time (s) Merc to ftr (km) Merc to ftr (km/s) mm to ftr (km) mm to ftr (km/s) mm to Merc (km) mm from Merc (km/s) mm to S/S hh (km) mm to S/S hh (km/s)
0 197,321,600 444 171,920,000 7,500 25,401,600 7,056 171,920,000 7,500
300 197,142,500 750 169,580,000 8,100 27,562,500 7,350 169,625,000 7,800
600 196,871,600 1,056 167,060,000 8,700 29,811,600 7,644 167,240,000 8,100
1,564 195,844,323.04 1,075.28 157,743,904 9,664 37,635,771.04 8,588.72 158,966,952 9,064
3,000 194,279,600 1,104 143,866,400 9,664 49,948,552 8,560 145,951,048 9,064
10,000 186,061,600 1,244 76,218,400 9,664 109,378,552 8,420 82,503,048 9,064
10,800 185,060,000 1,260 68,487,200 9,664 116,108,152 8,404 75,251,848 9,064
12,000 183,533,600 1,284 56,890,400 9,664 126,178,552 8,380 64,375,048 9,064
12,191 183,287,991 1,287.8 55,044,576 9,664 127,778,767.19 8,376.18 62,643,824 9,064
14,565 180,174,347.75 1,335.3 32,102,240 9,664 147,607,459.75 8,328.7 41,125,888 9,064
16,000 178,237,600 1,364 19,264,012.5 8,229 158,508,939.5 6,865 29,148,660.5 7,629
18,000 175,469,600 1,404 4,806,012.5 6,229 170,198,939.5 4,825 15,890,660.5 5,629
18,826 174,303,073.24 1,420.52 1,996.5 5,403 173,836,428.74 3,982.48 11,582,244.5 4,803
20,000 172,621,600 1,444 (177,808,939.5) (2,785) (6,632,660.5) (3,629)
23,329 167,703,701.59 1510.58 (185,065,750.83) (-610.58) (92,840) (300)
30,000 157,181,600 1,644
40,000 139,741,600 1,844
50,000 120,301,600 2,044
60,000 98,861,600 2,244
70,000 75,421,600 2,444
77,800 55,750,000 2,600
80,000 50,078,400 2,556
90,000 25,518,400 2,356
100,000 2,958,400 2,156
101,000 802,400 2,136
101,300 162,500 2,130

(9,064 km/s = 30.21 permil. 9,664 km/s = 32.21 permil. 5,403 km/s = 18.01 permil.)

Landmark times:

Note that, due to the bulk of the Sirius/Sol Second Guard, Mercurand does not want to come DIRECTLY into the hyper hole. Assuming the Second Guard is 100 km in diameter (50 km in radius), and that it's 3000 km from the hole, Mercurand would have to come in at an angle of at least 1 degree to avoid colliding with the Second Guard.

Note also that, despite Ken's insistence that they can't afford to waste any deceleration while they're crossing the fighter's engagement envelope, there's an option Ken didn't consider. Let's say they REALLY miss the mark, and reach the turn-start point going a whopping 420 km/s instead of the 300 km/s they need. Mercurand could still brake to a dead stop in only 4,410,000 km, which would leave them on a line nearly perpendicular to the Sirius/Sol hyper hole's face 4,500,900 km away. They could then accelerate directly toward the hyper hole and be going up to 424 km/s (over 1.4 permil) by the time they reach it.

Strategies and tactics

Attacking a star system is like laying siege to a castle.  The defenders always have the edge.  No spacecraft larger than 200 meters across can fit through a hyper hole, but spacecraft and gate guards several kilometers wide will be waiting on the other side to tear apart any intruders.  And even if your fighters or deployers do fit through the hyper hole, any large scale assault force will have to come through one spacecraft at a time.  The first dozen or so fighters sent through will usually be blown to bits before they can inflict enough damage on the gate guards (and neutralize enough gate guard weapons) for the rest of the assault force to squeeze past what's left of the first line of defense.

Missiles that can acquire a target outside the firing craft's line of sight can make the initial assault less costly.  The problem is, such missiles have to be going slowly enough to make sharp, unforeseen course changes, and this makes them easy targets for gate guard point defense systems.  The solution: drones.  Drones are much more fragile and far less intelligent than fighters, but if a missile can be fitted with automatic target selection, hey, so can a drone.

In gate guard assaults, and in the rare fighter-to-fighter clash, drones are also useful for drawing some enemy weapons fire, since drones can usually fire their onboard weapon more than once and can stay outside the range of a point-defense system.

Active radar absorption has limited utility, because it's impossible to hide a spacecraft's heat emissions.  About the only way you can "sneak up" on an enemy spacecraft is if you come at it out of the sun, so as to be in its heat sensors' blind spot.

Evasive maneuvering:

To keep from being hit, military spacecraft engage in evasive maneuvering — either a "full evasive", which maximizes the spacecraft's random movements relative to a specific attacker but throws course-following or on-course-acceleration out the window; or a "partial evasive", which seeks to keep the spacecraft more-or-less on course and accelerating in the correct direction while simultaneously offering a limited degree of random movement.  Both these maneuvers require the spacecraft to rotate extremely rapidly, so as to change the direction the engine is pointing quickly.  A quick calculation shows that, for a 30-meter-long rod-shaped spacecraft with attitude thrusters at either end, achieving an angular acceleration of 1 radian/sec2 requires each of the two attitude thrusters to produce enough force to accelerate the entire spacecraft at a quarter of a gee.  For a 200 meter long fighter, this same angular acceleration requires each thruster to produce enough force to accelerate the entire spacecraft at one-and-two-thirds of a gee.  For a 500 meter long Deployer, four-and-one-sixth gee.  This means military attitude thrusters need to be exceptionally powerful, perhaps being miniature hot-fusion engines in their own right (or using thrust vectoring from the main engine).  It also means that a Deployer, with its 2g main engine, will need thrusters at least twice as powerful as its main engine.  It can do better evasive maneuvering by letting these massive thrusters push it sideways than it can by twisting around to point its main engine in a different direction.

On those rare occasions when actual personnel go into combat, Sol and Sirius use the same traditional army organization structure that's been in use on Earth for hundreds of years:

Ideas for other short stories or novels set in the Pentagon War universe

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