"I must say, I'm impressed," Ken said after wolfing down the last bite from his plate. "That actually tasted like real bacon and eggs."
"Glad you like my cookin'," Jennifer teased. "I knew we'd have at least a couple of meals under thrust, so I made sure the Logistics folks packed some gravity-friendly vittles." She turned to the Centaurian. A full bowl of loose grain sat on the counter in front of it, a shallow finger dent the only mar on the grain's otherwise symmetric surface. "Torra, you've hardly touched your . . ." she searched for the word, "odvrutl."
"I ate yesterday," Torra Zorra replied matter-of-factly. "I did sample a couple of kernels, but this oood(v)(r)uut(l) tastes a little funny."
"What do you mean?" Jennifer seemed a little hurt. "I made sure they packed the strain native to your homeworld."
Torra puzzled for a moment, then raised all four hands in understanding. "Now I recognize the flavor. That's the western Go'orla strain. Clan Zorra isn't from Go'orla, we're from Alpha Centauri B-II! We moved there even before First Contact."
"Is the flavor really that different?" Jennifer asked.
"You bet!" Torra replied. "B-II is a water world — no land masses. All the colonies basically float on the ocean surface, which meant the early colonists couldn't afford to pile the soil in their 'farmlands' very thick. But the undergound water table on Go'orla is basically at sea level, which means normal oood(v)(r)uut(l) has a really deep root system to reach the water. The original colonists had to engineer the grains to have short roots so that they could thrive in the thin, artificial soil of a B-II colony. They'd been breeding in that environment for a century-and-a-half when Clan Zorra left for New France, and it was the seeds for those grains that the clan took with 'em. So of course they're going to taste different."
"So," Jennifer said, "Your ancestors we New France colonists, then? They weren't first generation Human-Centaurian?"
"Mine weren't either," Ken interjected.
It was almost imperceptible — Torra certainly missed it — but Jennifer's eyes opened just a tiny bit wider when Ken said that.
"My great great grandparents came over in the second wave," Ken went on. "We were Martian — er, by which I mean, South Martian."
Jennifer smirked. "I figured you weren't North Martian. You don't exactly look it."
"I also don't speak a lick of Mandarin," Ken agreed. "But, actually, there were a surprising number of Martians and North Martians that came over at the same time. To this day, I still hear folks occasionally refer to Human-Centauri II as New Mars."
"My ancestors are first-generation," Jennifer offered. "We immigrated here before it was trendy. We made a home for ourselves in the Capital before it was called the Capital. Human-Centauri wasn't even a star system yet. We had to figure out centrifuge-making as we went."
Ken countered, "And you had to walk 40 klicks uphill both ways in a blizzard just to go to school, right?"
"Blizzard?" Torra asked.
"Terrestrial weather phenomenon," Ken explained. "Snow and wind."
Torra could only reply, "And what's 'snow'?"
"Don't they have cold weather on Gorla?"
"They might," Torra answered, "I wouldn't know, the closest I ever got to Go'orla was when I caught a connecting flight on one of its orbiting spaceports. But they don't have cold weather on B-II, I can tell you that. The high carbon dioxide levels and constant cloud cover mean the whole planet's pretty much the same temperature all over. I take it 'snow' is something you get in cold weather on Earth?"
"Yeah," Ken clarified, "Ice crystals falling from the sky, kind of like frozen rain. It can accumulate in big, thick layers on the ground. You can play in it and even ski on it."
"You might," Torra twitched. "That much cold would send me into hibernation in no time flat."
A chime interrupted from the wall speakers. The S.I.'s voice intoned, "Mercurand will rendezvous with the run-up intercept point in ten minutes."
Ken glanced at his data pad. He'd set it to receive constant updates from Mercurand over intracraft wireless, and it now showed the latest Nav display. "Yep," he confirmed the S.I.'s assessment.
Jennifer said, "We've got a few more minutes before we need to get back to our stations. Have either of you ever stepped foot in the Sirius system before?"
Torra pushed away with its hand, making the Centaurian gesture for "no."
"Actually," Ken said slowly, dredging up an old memory, "I did once, back before I joined the HCDF. A buddy of mine —" He cut himself off as he looked at Jennifer, then waved a quick hand in dismissal. "Oh, you don't know him. He and I paid a very brief visit through the HC/Sirius hyper hole in a mini."
Torra pointed an eye directly at Ken in astonishment. "You have a mini?"
Ken chuckled slightly. "Are you kidding? I could never afford something that extravagant. This was my buddy's mini. At least, I think it was his. Knowing him, there was always the off chance he might have 'borrowed' it from someone else and neglected to tell them about it. All I know for sure is that he prodded me to come with him up to synchronous station 23 because he had a 'surprise' waiting, and when we got to the terminal there, boom, there on the far side of the airlock was the main hatch of a Keylance. It couldn't have been more than a month out of the Ceres assembly plant. I remember we had to pre-breathe pure oxygen to get the nitrogen out of our blood before we went in, because the cabin was pressurized at only a fifth of an atmosphere instead of the standard half-atmosphere pressure. The Keylances do this so that they can install these humongous windows in the flight deck. The view is just unbelievable from inside it, almost like you're in a giant observation bubble. He got departure clearance, we undocked, and we did a near-brachistochrone straight into the departure queue for the HC/Sirius hyper hole. Man, was I ever excited. The hole was only three years old back then, and the whole idea of visiting another star on a whim still felt more like fantasy than reality."
"Three years," Torra muttered, counting on some of its tentacle-fingers. "So . . . this would've been ten years ago?"
"Just about, yeah," Ken confirmed. "And I'll tell you, when our nose poked through the hyper hole and that whole new star system slid into view around me, it was like being in a storybook land. Sirius A is huge. It's almost half as big around as Human-Centauri's entire Habitat Ring. We came out of the hole almost two A.U.s away from it, and even with the window's glare tint engaged it still hurt my eyes to look at the star. And the star system had so much elbow room in it! The three million klicks separating our habitat ring from that tiny little red dwarf in the center of our system seems positively cramped by comparison."
"But then again," Jennifer offered, "We have something Sirius doesn't. We have Human-Centauri."
Ken nodded almost dismissively. "Yeah yeah. 'The plague shall pass.'"
The Colonel looked as though she were about to reply, but at that moment another chime ushered from the speakers, followed again by the S.I.'s voice: "Mercurand will rendezvous with the run-up intercept point in eight minutes."
"Time to get back to the command center," Jennifer said.
Torra picked up its uneaten bowl of oood(v)(r)uut(l) and dumped its contents back into the grain storage bin, making sure the seal wouldn't let any grain float out when microgravity returned. It wheeled down the short hallway to the command center, Ken and Jennifer following behind with those slow human legs of theirs. It was hardly worth gloating about, though; 1g was just about the upper limit of Torra's foot wheel tolerance, and that only because it had had plenty of opportunity to practice wheeling about in 1g on Marsidor. If circumstance called for the engine to be throttled up to even 1.1g, its wheels wouldn't support its weight; it would have to waddle along the floor on four stumpy little legs. It rounded the final corner, leaning into the turn, and rolled into its still-open surround station. Among the displays now surrounding its eyes, one of the smaller ones echoed the data from the Navigator's main screen, which had been vigilantly updating itself in Ken's absence. The Nav display on the humans' repeaters was 3-D, but the current view was completely flat, showing the plane of Human-Centauri's ecliptic with nothing popping out or sticking in, as befitted a Centaurian's monocular vision. A blue arrow on the screen represented Mercurand's current location and velocity vector, relative to the Human-Centauri sun. Beneath it, a razor-thin solid line represented Mercurand's projected course if it continued at this acceleration. This course line slowly converged toward another, dashed line on the plot: the run-up line for the peacetime-arrival side of the Sirius hyper hole. They were nearly in position.
Jennifer and Ken trailed in and sat at their stations, checking their displays to ensure nothing unusual had cropped up that the S.I. had missed. "We've got a couple minutes before we can start the run-up," Jennifer said. "I'm going to contact our Gate Guard to coordinate—"
The S.I. interrupted, "Receiving a datagram from the HC/Sirius hyper hole. It appears to be encrypted. Header claims the sender is the hole's Gate Guard."
"Speak of the Devil," Jennifer conjured up the quaint expression. She scanned the display that currently served as her comm console. The encryption code matched the public key the Chairholder's office had issued for their mission. The S.I. ran the packets through the decrypter's matching private key, and played the audio: "This is HC/Sirius Gate Guard. This message is for Mercurand. We've been instructed by the Chairholder to offer you any assistance we can. We await your instructions."
Jennifer smirked. Short, and to the point. She typed a short key sequence that meant "record with encryption," and spoke into her console mike: "Sirius Gate Guard, this is Mercurand. We intend to make a high speed transit through the retrograde end of your hyper hole. We request that the rubble barricade be moved aside, at least to the point where we'll have a clear corridor perpendicular to the hole's retrograde surface." She ended the recording, and said, "S.I., send the message I just recorded to the Gate Guard. Encrypt with their public key."
A brief pause, then the wall speakers answered: "Done."
"Round-trip transmission time at this distance should be . . ." Jennifer glanced at the plot to remind herself, ". . . 30 seconds."
Ken frowned. "But . . . our Rock Pile is right in front of the hyper hole. The Sirians can see the rocks. Won't moving them around tip our hand?"
"The whole area on our side of the Hyper Hole is still in chaos after Santa Maria's incursion," Jennifer explained. "The Sirians had to move a lot of our barricade aside before they could get their fighters and Deployers though; our Autopushers are doubtlessly still getting the Rock Pile back into shape. So, Sirius will probably interpret any activity there as our effort to plug up the hole. They won't suspect that we're actually unplugging it."
Ken's voice was somber. "Let's hope not."
A light blinked on Jennifer's comm console just as the S.I. spoke up again: "Receiving a datagram from the HC/Sirius hyp—"
Jennifer smirked as she tapped the "decrypt" soft-button on her comm console, interrupting the S.I.. She wasn't going to wait around for Mercurand's electronic brain to tell her the whole life story of another transmission that was obviously from the same people. The message played: "Mercurand, Sirius Gate Guard. We're instructing our Autopushers to clear you a corridor through the Rock Pile. We'll have a corridor for you at least a hundred meters wide by the time you're scheduled to arrive, but be advised that clearing all debris from your path is neither feasible nor advisable."
Jennifer recorded her response: "Understood, Sirius Gate Guard. Just be certain there's not so much as a sand grain in the corridor you do clear. We'll be going one permil, and Mercurand's whipple armor is only one layer deep. Mercurand out."
Torra did a quick calculation while the response went out. "Against one permil impactors, the whipple layer should be sturdy enough to ameliorate any object massing up to three grams."
"After which, we'd have a hole in our armor," Ken pointed out.
Torra bent slightly away from Ken in a Centaurian shrug. "True."
Ken glanced at his displays out of the corner of his eye, and instinctively moved his hand to the thrust control lever. It was a redundant control; he could just as easily have typed in a command or ordered the S.I. to change thrust to a specific level. But the feel of the manual lever in his hand, the instant feedback it gave him, was one of the reasons he'd taken up piloting to begin with. "Coming up on intercept, throttling back to point three gee."
The muscles of Torra's torso had locked themselves into place as soon as it had taken its station, but it could still feel the weight ebb from its feet. Now, lighter than on its species' homeworld — lighter, even, than in the centrifuge of its clan's homestead — Torra allowed its arms to drop naturally and enjoyed every moment of their slow fall. Zero gee was common enough, but moments of low gravity like this were an all-to-rare treat. As soon as their run-up started, if not sooner, it would be over, and they wouldn't have occasion to maneuver at low thrust again until they reached UV Ceti.
If they reached UV Ceti. . . .
The solid and dotted lines on Ken's display were now only a hair's breadth apart. He ticked down the seconds in his head. "Aaaaand . . . intercept!" The two lines merged and blinked briefly as Ken yanked the thrust lever all the way to idle, throwing Mercurand's whole contents into microgravity. Only a single solid line remained on the screen, going all the way off one side. Ken zoomed outward, increasing the scale until both Mercurand and the Human-Centauri/Sirius hyper hole fit onto the same display. It all looked right. He took a deep breath. "Ready for run-up when you are, Colonel."
"All right," Jennifer said. Even in freefall, the line of her mouth was grim. "We're committing. Nav, throttle up!"
Ken rocked the thrust lever forward, pushing everyone back down to the floor again. "One point zero gee! We'll reach the hyper hole in eight hours, twenty-five minutes, at an intercept velocity of two-nine-seven klicks per second."
Jennifer encrypted one more message for the Gate Guard's benefit: "Mercurand is starting its run-up now. Estimated time en route 8 hours 25 minutes, estimated intercept vector —" she checked her repeat of Ken's plot "— three zero zero by minus fifteen at one permil." She sent the datagram off, then clapped her hands together. "Well, gentlemen and Centaurians, since we appear to have an entire work shift before we enter the jaws of hell, let's do some detailed planning."
"Hmm," Ken smirked wryly, "It's too bad we did our sleeping during the last leg. I'm not sleepy enough to catch a nap during the run-up, and I have a feeling none of us will be able to sleep while we're in Sirian space. There are two hundred million klicks separating the Sirius/HC hyper hole from the Sirius/Sol hyper hole right now; even if we barrel toward the Sirius/Sol hole at 2g without slowing down, we'll be in Sirius space for a day-and-a-half."
"And we'll almost certainly have to slow down," Jennifer agreed sourly. "Unless you've got a navigator's miracle up your sleeve, there's no way we can fly through a 200-meter target at five or six permil while pulling evasives on the way in. That means we decelerate to rendezvous with the Sirius/Sol hyper hole, and that means at least two full days in the Sirius system."
Torra made a gutteral noise with two mouths. "Two days at two gee. Could you humans even sleep if you wanted to, in that kind of weight?"
"Ooh," Ken wrinkled his eyebrows, "That's another problem I hadn't thought of: fatigue. I've stayed awake for two days straight before, but that was under Martian-strength gravity, point four gee. I could probably do it again at one gee, but at two? I'd much prefer to be fresh and sharp when we have to deal with the Sirius/Sol Gate Guard, not ground down by two days of being shoved into the thrust floor. Heck, breathing takes effort in two gee."
"Mmm," Jennifer covered her mouth in thought for a moment. "Depending on the tactical situation, we might be able to find a couple of hours when we can throttle back to one gee, or at least to a gee-and-a-half. But every moment we're below max throttle means more flight time, and more opportunities for the Sirians to attack us."
Ken sighed. "Personally, I think it's worth the risk, so long as we can keep our total flight time below three days."
"Why three days?" Jennifer asked.
Ken frowned. "It just seemed like a good round number." He pulled up a plot of the entire Sirius A system for all to see. "Right now, the capital world, Sirius A IV, is about four hundred million kilometers from any point along our trajectory. If they wanted to send any manned Deployers from their capital fleet out to get us, assuming they don't push their crew any harder than 2g, they'd take 2.3 days to arrive at 13 permil relative, or 3.3 days to make a rendezvous-intercept — and that's assuming they even knew ahead of time what trajectory we were going to take. If we keep the flight time below 3.3 days, we take away that last option."
"Their capital fleet can still send fighters after us without their Deployers," Torra said, "And at 100g they'd reach us long before we even reached the half-way point."
Jennifer grunted with a grin. "But long-range fighter intercepts are expensive. They use up a heck of a lot more deuterium than a Deployer intercept, and when a fighter returns to its Deployer after such a long haul its fuel tanks are going to be close to empty. Just about every Deployer in service only carries enough extra protium and deuterium for one complete refuelling per fighter, tops, which means the Deployer itself will need to take on more fuel soon afterward. The war's been dragging on long enough that they might not want to waste long-range fighter intercepts on one tiny intruder who's not even headed for any strategically important targets."
Torra closed the two eyes facing away from Jennifer, the Centaurian equivalent of furrowing its brow in concentration. "What do we know about the Sirians' strategic deployments in-system? Do they have other bases with fighters or Deployers that'll be closer to us than Sirius A IV?"
"That we don't know," Jennifer shook her head.
Ken felt a hard lump in his stomach. "Yes we do." He brought up the system plot again and highlighted a different one of Sirius A's four planets. "Sirius A I. It's in synchronous rotation with Sirius A, so the same sides are always in day or night. The day side's way too close to Sirius A to live on, but the night side's pretty nicely populated."
Jennifer puzzled. "But the planet's got no atmosphere. They can't even terraform the place."
Ken looked her in the eye. "That never stopped us."
Jennifer raised her eyebrows, surprised she hadn't made that same connection. "Point taken."
"We might not know their strategic deployments," Ken went on, "But you can bet your life they're going to have at least a defense fleet guarding Sirius A I, and maybe even a Deployer base. And right now, Sirius A I is on the same side of Sirius A as our projected course."
Jennifer winced. "Let's just hope it is only a defense fleet there and not a strategic threat response base. And that they don't have cruise missiles."
"Guess hoping is the best we can do there," Ken agreed with some resignation. "Now, I'd like to focus on something we'll have a little more control over. What about the first few thousand klicks? We know about where their Gate Guard is going to be, relative to the side of the Sirius/HC hyper hole we're going to pop out of, and thanks to lying right along our line of sight we know exactly where their Second Guard units are stationed."
"Right." Jennifer's mouth tightened as she envisioned the first few seconds of their incursion. "The instant we're through, we'll want to go to partial evasive, two gee."
Ken nodded. "I concur." In a full evasive, you pointed your nose 90 degrees away from your attacker. In a partial evasive, you never let your nose get more than 45 degrees away from the direction you intended to accelerate toward. It was a compromise that got you where you were going without leaving you a complete sitting duck, but it still cut your survival odds in half compared with fully evasive maneuvering. "Course directly for the Sirius/Sol hyper hole?"
"No," the Lt. Colonel answered, "Dip us below the ecliptic. Get us as far from their Second Guard units as you can. Don't come back onto course for the Sol hyper hole until we're past them."
"So that's why you had me line up at only one permil," Ken realized. "You're more worried about the Second Guard than you are about the Gate Guard."
Jennifer smirked. "You got it. We'll be pulling away from the Gate Guard at one permil, so its short-range missiles won't be able to touch us. Even our meager two-gee partial evasive should give us better-than-even odds against their unguided weapons, if they don't see us coming. But their Second Guard is going to have six or seven precious seconds to get their act in gear before we're past it, and if they get off any missiles we won't have much time to knock them out." A new thought made her turn to her weapons officer. "We can knock out enemy missiles, can't we, Torra?"
"Yeah," the Centaurian replied uneasily, "We have twenty shrapnel rounds in our magazine for just that purpose. But . . . we're only going to be a couple of seconds' flight time from the bogey that's launching them, right? Well, given the cycle time on our slug launcher, we'll only have enough time to fire once while their missiles are on the way in. That means the best we can hope for is to take out one of their missiles and dodge the rest."
Ken shook his head, remembering his earlier conversation with Torra. He'd better make sure not to portray their situation as hopeless. "Well," he offered, "The Second Guard shouldn't be expecting us any more than the Gate Guard will. They might not be able to react in time to get off any missiles at all before we're past them. Or their fire control might only be able to get off a couple of missiles in the time they have. We're just going to have to count on getting a bit lucky, is all."
Jennifer nodded. "Yeah."
"So," Ken moved on to his next concern, "After we're past the Second Guard, if the Sirians don't want to let us through unchallenged, how should we approach the Sirius/Sol hyper hole? A least-time rendezvous-intercept would —"
"I can see where you're going with this," Jennifer cut him off. "And I agree. Any low-speed approach to the other hyper hole will make us way too easy a target. Think you can hit it at one permil?"
"Even at a 5 degree approach angle," Ken boasted, "I've hit dead-center on a hyper hole at three permil." In response to Jennifer's raised eyebrows, he quickly added: "In simulation, at least. I've never had the opportunity to test that maneuver in real life."
"All right, then," Jennifer replied, "barring a miraculous ceasefire from the Sirians, we'll make a one permil at-speed approach to the Sirius/Sol hyper hole. That means we get right back on a direct line the moment we're past the Second Guard."
"Uh, actually," Ken said, looking at the Sirius A system data. His eyebrows shot up. "Oh! Actually, it looks like right now, the Sirius/Sol hyper hole is pointed at a right angle to the Sirius/HC hyper hole. If we followed a direct line, we'd be approaching it edge-on."
"Hm," Jennifer frowned.
"If we're going to do an at-speed approach, we'll have to swing wide, and come in sideways. That means . . ." he plotted a course, ". . . we put ourselves on a vector 1.41 degrees off from the Sirius/Sol hyper hole, and aim for a speed of one permil at this point," he tapped his display, "6.7 million klicks away from the hole. Call it 'point gamma.' Then we point our engine at a right angle to our course and follow a circular path four-and-a-half million klicks in radius. That 90 degree arcing turn will burn up nearly 1.6 permil worth of delta-v, but at the end of it we'll be three hundred thousand klicks away from the Sirius/Sol hyper hole, and headed nearly dead-center to where the peacetime-departure side of the hole will be pointing at that moment. Doing that powered turn would have two advantages over braking to a stop and then re-accelerating to one permil: it would actually use up less delta-v, and it would mean we wouldn't be a sitting duck at any point along the route."
The Colonel rubbed her chin. "What if our combat contingencies mean it takes longer to get there, or we end up getting there sooner than we'd anticipated? The hole will be pointed at a different angle then, won't it?"
Ken smirked. "Thankfully, the Sirius/Sol hole rotates so slowly that even if our timing is off, our approach angle will be just about the same and point gamma won't need to shift. We won't have to re-project our course."
"Sounds doable, in that case," Jennifer said, "And . . . it doesn't look like there's much tactical planning left for us to do, is there? Once we're past the Second Guard, we can only play it by ear, and react to whatever they throw or don't throw at us."
Ken sighed. "I think you're right." He turned to the Centaurian. "Unless you've got some ideas for more planning, Lieutenant."
Torra merely held up one hand in a Centaurian "No."
Ken glanced at his plot. The blips had hardly moved. "It's going to be a long eight hours."
Torra had busied itself in the hibernation room, checking the odds and ends of its refrigerated cocoon and learning what it could about the humans' S.M.S. coffins. Sure, the S.I. had already done a walkaround of the hibernation room, and every other interior space in Mercurand, using an assembler bot for its eyes; but a personal inspection made for a good distraction. It beat thinking about the chaos that was about to descend.
It lifted its data pad to to check the nav plot. Torra had never gotten completely used to working in a full 1g, and could feel the strain as its arm fought upward against its unnatural weight, until at last the data pad reached eye level and the muscles could lock in place. Then, Torra twitched — they'd intercept the hyper hole in only 8 minutes 43 seconds. It was time to rejoin the hunting party. It took a deep breath, filling its four lungs as calmly as it could, and rolled down the corridor back to the Command Center.
In the C.C., Ken was as frazzled — in his own, human way — as Torra. He was pacing back and forth in what little free space the room had, his hands clasped behind his back, his head pointed straight down at the thrust floor. He probably hadn't done anything but mull over their impending peril the whole time. The Lt. Colonel, though, seemed as calm as ever. Torra wondered if she was feigning a show of confidence to inspire her crew, as human leaders sometimes did, or if she really just wasn't that nervous about the situation, which seemed downright insane right now.
Jennifer made sure her transmitter was set to the same encryption key as before, and keyed her mike. "Sirius Gate Guard, Mercurand, inbound from your one two zero by plus fifteen from one two six thousand klicks, E.T.E. seven minutes. Requesting final exact position data for the hole you've opened in the Rock Pile."
This time, the response came only a couple of seconds later: "Mercurand, your corridor is slightly less than a hundred meters wide at its narrowest, but we did manage a straight line facing your vector. Data packet attached."
The data file that followed got dumped directly to Ken's station and fed into his plot. He flicked a few keys, and a pink arrow appeared on the plot, overlaying the hyper hole. It lined up almost, but not quite, perfectly with their course line. "We're gonna have to make a little course adjustment to hit that corridor. Correcting now." Another couple of keystrokes, and they could all feel the thrust floor below them shift ever-so-slightly as the whole spacecraft rotated. Their plotted course line became slightly curved, and now mated perfectly with the pink arrow at its end.
"Six minutes, forty seconds to transit," Ken intoned. The pit of his stomach was curled in knots. He'd gone to the bathroom less than half an hour ago — thankfully, without the need to use any of the messy plumbing attachments he'd have to put up with if they'd been in zero-gee — yet he felt like he needed to use the bathroom again. It was an illusion, he knew that, a side effect of nervous anticipation. He'd typed up an explicit program to throttle up to 2g and switch to partial evasive the moment they made transit, and immediately change course to avoid the Second Guard; and he'd set this program running hours ago. Yet even now he found himself glancing at his execution screen again, as he'd done so many times over the last eight hours, just to make sure his instructions hadn't gone anywhere when he wasn't looking.
Torra could prepare even less. It had readied the E-43 before it had even wandered off into the hibernation room; a shrapnel round, nine hundred grams of scored ceramic sitting on a hundred gram steel pusher plate, had been autoloaded into the back end of the slug launcher and secured. That round was still there, and the S.I. had brought the launcher into a fire-ready state minutes ago in Torra's absence. The Centaurian weapons officer checked the radars, the thermal detectors, and the tactical plot once more, but they were all as green and functioning as they'd been hours earlier. It wished Mercurand had active radar absorption, then they'd at least be able to avoid enemy radar locks; but the inside-out QC&C generators required for A.R.A. would have massed nearly half as much as the rest of the spacecraft.
Jennifer switch a display to visual. Mercurand's forward camera showed her a tiny crescent, the Sirius Gate Guard asteroid, now less than a hundred thousand klicks ahead. It was the last friendly thing they'd see. At a full permil, both the rubble of the Rock Pile and the hyper hole at its end would flash past them too fast to be noticed. She keyed her transmit mike for the last time. "Sirius Gate Guard, Mercurand. We'll be too busy for the rest of our approach to update you on our status. Maybe we'll say hello again in twenty years. Keep up the good work, guys. The plague shall pass."
"Understood, Mercurand," the speakers replied an instant later. "We'll advise if our situation changes before you get here. Good luck."
"All right," the Colonel addressed both her subordinates, "We'll be in hostile territory in less than six minutes. As of this moment, we're at condition red."
"Yes, Commander," the two replied almost in unison, switching to the mode of address she held while in battle.
Ken and Jennifer tipped their seats back, the attached displays keeping pace with their relative positions around their heads, and moved their key consoles to their armrests. Their seats were now makeshift seatcouches. There wasn't much Torra could do to ready itself for greater engine thrust, though. All they could do now was count down the agonizing minutes.
Two. Ken's gut churned. Torra twitched.
"Here it comes," Jennifer muttered as the count reached ten seconds. She glanced sidelong at her navigator, who only nodded in nerve-wracked readiness, then at her weapons officer whose alien mien she couldn't read. On the forward visual, the crescent of the Gate Guard irised ever larger until, dead ahead, they caught the glitter of reflected Human-Centauri sunlight off a tiny donut of rubble. The Rock Pile, and the frighteningly narrow clear corridor down its center, rushed toward them and flashed to cover the full frame in a heartbeat.
In one ten-thousandth of a second, the 30-meter length of Mercurand passed through the Human-Centauri/Sirius hyper hole from nose to engine. At the same time and with equal speed, Mercurand shot out the Sirius/Human-Centauri hyper hole on the other end, four-and-a-half light-years from home.
Instantly, their weights doubled and the room pitched nauseatingly forward. The engine had kicked into high gear, and the automatic partial-evasive maneuvers program had started. Torra scanned its tactical plot as quickly as it could; the Sirian Gate Guard, as expected, had been out of line-of-sight on their way in and only appeared on the plot now that they were in Sirian space; but so, ominously, had been the bulk of the Second Guard units. The Second Guard at this hyper hole was no asteroid base like the Gate Guard was, but it consisted of a larger pile of spacecraft than any of them had expected. Almost by instinct, Torra flicked one hand and tagged the entire Second Guard group as the number one threat. Ken's course line superimposed itself over this field of targets, and showed just how frighteningly close Mercurand would be when it passed the Second Guard ten seconds from now.
The Gate Guard, already behind them, opened fire with kinetic slugs, short-range missiles, and — as far as Torra could guess, since there was no way to see the misses — lasers and magnetic snares. The missiles would never catch them. They were limited to the same 100g of acceleration that fighters were, which meant that with Mercurand's initial speed advantage of a full permil — 300 kilometers per second — they wouldn't even match their target's speed for another five minutes, by which point their fuel would be nearly exhausted. The slugs left their launchers at ten permil, but they were unguided; only one nation had yet engineered a guided kinetic slug, and no other nation — not even Sol, as far as anyone had heard — had yet figured out how Alpha Centauri's liquid metal gun worked. Against an evasively maneuvering target, even one on partial evasive as Mercurand now was, unguided slugs had as much chance of scoring a hit as a golfer did of scoring a hole-in-one while blindfolded. Only a shrapnel pack would have had a chance of hitting them, and mercifully, it appeared that the Gate Guard's knee-jerk response hadn't included any fragmentation kinetics in the mix. The tiny chunks of metal all whizzed by ineffectively on Torra's tactical plot.
But the Second Guard platforms, still nearly dead ahead of them . . .
"Missile launches from ahead!" Torra barked with the mouth facing the Colonel. "Five of them! Chaff away!" He pressed a hard button he'd readied for just this purpose, and Mercurand's tiny chaff ejectors spat out three-centimeter spheres in all directions. These chaff balls, far smaller and less sophisticated than thermal decoys, shone as brightly as they could in the thermal-infrared and microwave ranges. Their purpose wasn't to fool the enemy into thinking there was more than one target; it was merely to confuse the thermal detectors and radar-return sensors of missiles, which were too small to carry their own S.I., while on their terminal run. Torra's musculature twitched in its ready-at-any-instant stance as the next three agonizing seconds ticked by, then, with a mix of relief and new alarm, three of the five missile-blips on its plot switched from a bright red to a dull gray-yellow as the tactical analysis figured out which ones had veered off ever-so-slightly to hit chaff instead of spacecraft.
That left two birds still homing in on them.
Torra now had to decide which of the two incoming missiles to shoot with their only point-defense weapon. Which one stood the greatest chance of hitting them, despite their evasive maneuvers? It wasn't a decision the tactical analyzer had been programmed to make, nor would the S.I. be able to arrive at a solution without studying the problem space beforehand. Torra kept one eye on its radial plot, which showed both red dots from Mercurand's vantage point as though the spacecraft wasn't gyrating. One of the dots veered and jinked wildly against the background stars as it tried to correct for Mercurand's unpredictable maneuvers, but the other hardly appeared to move at all. That was the missile with the best tracking. Torra selected it, then jabbed one tentacle-finger down on a stud. "Firing!"
There was a muffled bang!, and the room lurched violently to the left. The shrapnel pack flew out of Mercurand's side, heaved to ten permil by magnetic forces lasting only a fiftieth of a second. Just as it reached the end of its ten kilometer acceleration track, the 900-gram ceramic payload shattered into 900 one-gram shards along its score lines. Each of those shards packed a punch equal to a tonne of TNT. One of the shards flew outward right along the track that the target missile happened to be on. It plowed straight through the missile's cryogenic deuterium tank, flash-heating its contents to a gas; the tiny fuel tank lacked the pressure safeties of the tanks in a manned spacecraft or a fighter, and simply exploded.
Now, only one missile continued to angle toward them . . . too close for the slug launcher to queue up the next shot in time.
As it happened, the one remaining missile had been jinking so manically because one of Mercurand's chaff balls had almost, but not quite, fooled it. The tiny guidance system kept waffling, choosing one radar-and-thermal source, then the other, until finally it split the difference and came in exactly between the two . . . thereby missing both potential targets.
"A miss!" Torra exclaimed.
"We're past 'em!" Ken announced a second later.
"I'm seeing kinetics," Torra reported, watching telltale spikes erupt on tactical from the now-receding Second Guard units. "Two slugs just missed us. Damn close, too. Good thing they didn't have any shrapnel packs loaded."
"They were expecting fighters," the Commander said with a smirk. "How long before we're out of their unguided attack envelope?"
Ken squinted at his 3-D course display. "I'd stay on partial evasive for at least another two minutes, just in case they're mounting proton cannons."
Torra checked Ken's course plot. "Uh . . . you'd better make that three minutes. Mercurand doesn't have anything approaching a military-strength magnetic protection field, so even a glancing hit from a particle beam can be lethal."
"Good idea," Ken acknowledged. "Of course, if they're mounting lasers . . ."
Torra twitched at the thought.
"We'll just have to hope for the best," the Commander answered, "And hope that if they do train any lasers on us, our gloss finish will be enough to prevent a burn-thr—"
Their weight suddenly reversed, throwing them toward the ceiling for a fraction of a second before they slammed back down onto the thrust-floor. Torra recognized the sensation instantly. "Magnetic snare!" It checked its readouts with some relief. "We're going too fast for it to hold us." It made a gutteral snort with two mouths, a Centaurian's way of chuckling. "We probably ripped their emitter right out of its housing."
Mercurand hurtled farther and farther from the Gate Guard and Second Guard. Tactical still picked up kinetic weapons fire zipping past them, and an occasional proton cannon telltale; but with each passing kilometer their odds of survival grew. The spacecraft's partial-evasive gyrations now averaged out to a thrust vector that would, eventually, put them on a course 1.3 degrees off from the Sirius/Sol hyper hole 200 million kilometers away. After three minutes, when their attackers lay some 54 thousand klicks behind them and seemed to have given up shooting at them, Jennifer said, "All right, take us off partial evasive and stand down from red alert. But don't take us below condition yellow so long as we're in hostile territory."
"Yes, Colonel," Ken replied, dropping the "Commander" title that had evaporated at the same time condition red did.
"And keep an eye on the Gate Guard and Second Guard back there," she addressed her weapons officer, who literally could keep one eye on them while pointing the other two elsewhere. "If they start shooting at us again, we need to go back on partial evasive immediately."
"Yes, ma'am," Torra replied with the mouth closest to the Lieutenant Colonel.
"In the meantime," Jennifer continued, "Now that we've kicked in the door, it's time to tell 'em why we're here."
Torra froze. "You mean you want to tell them that we intend to fly through their other hyper hole? But . . . right now, they can only guess that that might be our destination. If we tip our hand, they'll know exactly where we intend to be at every moment!"
Jennifer's face, though Torra couldn't read it, was heavy with her somber mood. "Our original decision not to tell Sirius our intentions came from their stance on previous requests. There's an old addage: it's easier to beg forgiveness than it is to get permission. If we'd told them we were coming, they'd have been ready for us, and we wouldn't have had a chance in the universe of getting past their Gate Guard. But now that they know we're here, our best bet is to let them know we mean them no harm. I discussed this with the Chairholder before we left, and Yukariah Heap agreed with my assessment. In fact, when the Chairholder recorded the announcement that's currently aboard our message missile, that strategy got taken into account. S.I., bring up the Chairholder's recording."
A second later, the speakers chirped, "Recording ready. Size is twenty mebibytes."
"Ugh," Jennifer groaned. "How big is just the audio portion?"
"Seven hundred sixty kibibytes," the speakers replied.
"All right, then," Jennifer instructed. "I want the audio portion sent to the Gate Guard behind us, the Gate Guard at the Sirius/Sol hyper hole, every inhabited planet, and every known military space station in our database. Tight-beam it to each destination on a broadcast channel, to make sure each of them will be listening in. Then, launch our message missile."
"Audio extraction prepared. First transmission will commence in two minutes."
"Two minutes?" Jennifer puzzled. "That's an awfully long time just to get ready to send a message."
Ken smirked. "Not for a starship. Our comm laser is interstellar grade. It can send XRCP messages from UV Ceti, and have them arrive all the way back at Human-Centauri strong enough to be received. That means it has to put out some serious wattage and have one mother of an aperature to overcome the kind of diffraction you'll get over that distance. The whole assembly has to weigh nearly a tonne, and aiming such a beast while under 2g thrust can't be easy on the servomotors."
Torra puzzled, then paged through Mercurand's schematics with one eye. "But it says here the comm laser also serves as the forward ionizing laser while we're at interstellar speed. Doesn't that mean it has to sweep rapidly back and forth?"
"Doesn't have to do it accurately," Ken reasoned. "Just a crude gross jiggle or a phased-array sweep would be enough to completely cover our forward track. That's completely different from pointing it at a milliarcsecond-wide target precisely enough to nail it with the beam."
Jennifer frowned. "Will it take that long to re-aim the comm laser between each transmission too?"
The S.I. replied: "Average time between transmissions will be 25 seconds."
"Thank goodness," Jennifer said, "otherwise we'd be sending for over an hour."
One by one, hitting every ultraviolet receiver they knew about, Mercurand's recording of Human-Centauri's chairholder made its plea to Sirian ears:
"This is Yukariah Heap, Chairholder of Human-Centauri. The message you are hearing is being broadcast throughout the Sirius system, and is stored aboard a message missile bound for Sol space. It is only with the gravest concern for all our futures that we take such extreme measures.
"We have sent out a small starship with a new, experimental means of collecting the interstellar medium. Its destination is the UV Ceti system. We have strong reason to believe that there may be dire consequences, not just for ourselves but for the entire Pentagon, if we do not reach UV Ceti in ten years. Unfortunately, Human-Centauri is twelve light-years away from UV ceti. Our only hope to reach UV Ceti in time is to first route our starship to the Sol system, which lies only eight-and-a-half light-years from UV Ceti, and to do this the starship must cross Sirian space and transit through the Sirius/Sol hyper hole into Sol space.
"Let me emphasize that this starship is not a military spacecraft, nor is its mission military in nature. It is purely scientific. We intend absolutely no harm to either Sol or Sirius, despite the state of war that currently exists between our nations. As Chairholder of Human-Centauri, I beg you, Sirians and Solars alike, please, allow this one tiny spacecraft safe passage."
As the last transmission ended, Jennifer announced, "All right, launch the message missile."
Torra glanced at the destination program one final time, just to be sure the missile's planned course for the Sol hyper hole hadn't changed out from under it, then pressed a hard button. There was a barely audible clank as the ordnance clamps released, and a new dot appeared on the tactical plot with a friendly tag and a smooth 100g acceleration curve. "Bird away!"
"How long before it's in transmit range?" Jennifer asked.
Torra studied the plotted vector. "It should have line-of-sight to Sol's Gate Guard about half a million klicks from the Sirius/Sol hyper hole, but it'll have to make a 90-degree turn at the end of its run for the same reason that we do. I gave it a target speed of one permil in the turn, which, even with the one permil head start we've imparted to it, still limits its cruising speed to three zero permil. All told, after accelerating, cruising, braking, and turning, it'll hit transmit range and angle in . . . eight hours, thirty-seven minutes."
"Hm," Jennifer acknowledged, her attention already on another concern. "Torra, have the units behind us launched any cruise missiles?"
Torra instictively held up a tentacle-fingered hand in a Centaurian "No," then remembered Jennifer's lack of interest in Centaurian customs and rotated its eye turret left-and-right, hoping the gesture would look enough like a human shaking its head to get the message across. "No, ma'am. And the short-rangers the Gate Guard launched at us when we came through just hit engine shutdown. Maybe the Chairholder's recording worked, and they want to let us through."
Jennifer shook her head somberly. "If and when they do decide to grant us safe passage, they'd almost certainly tell us about it. More likely, the Gate Guard just doesn't have any cruise missiles to fire. They've been guarding the Sirius/HC hyper hole for over a year now, and not once in that time has anything made an incursion. They probably figured that anything we did send through would be easy enough to shoot down at close range. No, for now we can't assume anything about their intentions. All we can do is monitor the system for new thermal sources, and wait."
A speaker chime woke Torra out of a cat nap. Centaurians didn't need much sleep, but that didn't mean they never drifted off. Torra had been in a kind of energy-conserving mental stand-by state, aware of its surroundings but not really reacting to them above a subliminal level. That chime, though, almost always meant trouble, and Torra instinctively came back to full alertness and scanned its tactical plots. A new blip had appeared right on their projected track, and it flashed what would have been a gaudily bright orange to a human's eyes. Before Torra could read the codes next to the blip, the S.I.'s voice came from the same speakers that had just chimed: "New engine telltale detected, consistent with a fighter's engine pointed away. Radial velocity is one point five permil closing, no proper motion detected."
"Uh oh," Ken said as he too came alert, "Sounds like they've decided to intercept us."
"That bogey's coming from dead ahead," Torra said.
"How far away?" Jennifer asked.
"Can't tell yet," Torra replied.
"Hm," Jennifer mused, "I'm surprised it took 'em two hours to make up their minds. What probable operating bases are in that direction?"
Ken pressed a few keys. "Nothing we know about, other than the Gate Guard and Second Guards at the Sirius/Sol hyper hole. The intelligence database is coming up empty for this part of the system, and none of the other thermal sources we've been tracking since we got here are anywhere close by."
Jennifer rubbed her chin. "They must have detached it from one of the Second Guard units."
"But those are their Sol Second Guards," Ken said. "They're not like that little HC Second Guard cluster we passed on the way in, these are full-blown asteroid bases. They're smaller than the Gate Guard itself, but still enormous. Why would they station a Fighter Deployer there?"
Jennifer shrugged. "Who knows? They might be gathering for an offensive into Sol space, or paranoid because of a recent Sol attack, or maybe that particular Deployer just happened to need fuel when a transmute tanker was making a Gate Guard delivery. However it got there, we have to deal with it. Do we have an acceleration figure yet?"
"The cumulative data's just coming together now," Torra answered. "It's definitely accelerating directly toward us. Successive doppler deltas peg it at . . . 100g."
"Ugh," Jennifer groaned. "That's full throttle."
"Assuming the bogey is at the Sirius/Sol hyper hole right now," Ken said as he started running the numbers, "Or rather, that it was at the Sirius/Sol hyper hole 11 minutes ago, given the light-speed signal lag . . . if it follows standard procedure and accelerates to ten permil, and we hold our acceleration vector constant, it'll intercept us in 13 hours 9 minutes at 14.9 permil relative."
"And if it does a rendezvous-intercept instead?" Jennifer asked.
Ken punched a few more keys, letting the algorithm do the calculus for him. "14 hours 39 minutes."
"Hmm," Jennifer said, "If we survive it, and there's nothing else close by afterward, the best time to throttle back to 1g so we can get some rest might be right after the encounter with that fighter. We'll be, what, about eight hours from the course midpoint? The amount of time we lose by not accelerating at full that close to turnaround should be minimal."
Ken snorted. "Amazing. A hundred thousand tonne death machine is headed our way, and you're thinking about what we'll do afterward."
She shrugged. "Not much we can do in the meantime. We're not exactly carrying cruise missiles. We watch, and we wait."
Nine minutes later, Torra was still watching it, and the situation changed. "Ma'am, the engine telltale from the bogey just vanished. Looks like it stopped accelerating. Currently closing at three point five permil relative."
"Re-projecting intercept," Ken said as he tapped a few keys. "If we hold our acceleration constant, our vectors will converge in . . . uh oh . . . 26 hours 58-and-a-half minutes. That's way past the point when we'll have to turn around and start decelerating."
"Damn," Jennifer whispered, then voiced: "Why would they let us get so much farther in-system, instead of just accelerating to ten permil and intercepting us that much quicker?"
"If I had to guess," offered Ken, "I'd say they're under some strategic mandate to save deuterium. Their transmute tankers can only crank out deuterons so fast, so they don't want to expend any more than they have to. And, well, we're pretty small and slow as intruders go. They probably don't consider us enough of a threat to waste a full ten-permil intercept on."
"Still," Torra offered, "By now they must be thinking we're a pretty odd intruder. They'd only have to point a spectrograph at our tail to see that our exhaust is hydrogen instead of helium, and that our exhaust velocity is twice as high as a QC&C engine. The only kind of spacecraft whose exhaust looks even remotely like that is a transmute tanker, and we're way too small to pass for a transmute tanker."
Ken shrugged. "The Chairholder's message we broadcast did explain that our design was experimental."
"If I were them," Torra countered, "I wouldn't care what excuse my official enemies made. The weirder we look, the more unpredictable we become. They should be accelerating toward us as hard and as fast as they can, just to be on the safe side. And if anyone looks at our exhaust and jumps to the conclusion that we're antimatter-powered . . ." It twitched nervously.
"Or," Jennifer offered, "maybe that fighter wasn't carrying a very big fuel load to begin with." She shrugged. "We can hope. In any event, it looks like we're not going to get that opportunity to throttle down after the encounter. We're gonna need every scrap of speed we can spare."
Ken groaned. "Then we're stuck pulling 2g all the way through Sirian space?"
Jennifer nodded, almost in acquiescence. "Looks like it."
Ken pinched the bridge of his nose, the weight of his arms that much more acute. "I don't know whether to take sleeping pills or stimulants."
Minutes dragged by, then hours. The Sirian fighter, still trackable by the wan heat of its internal housekeeping activities, inched toward them with aching slowness. Torra had simply locked its musculature in place against the pressure of its own 2g weight, and could maintain this state for days with little ill effect. Ken and Jennifer, though, were as miserable as they'd been during their boot camp's endurance training, when they'd had to lie in a 2.3g centrifuge for 6 hours straight. Then as now, the boredom had almost been worse than the fatigue. Almost.
Then, five-and-a-quarter hours after the fighter made its presence known, a blip flared into life on Torra's long-range tactical display. It vanished as quickly as it had appeared; the Lieutenant paged through its recent event log, more in puzzlement than alarm. "That's odd, we just picked up a thermal flash from dead ahead. It was really dim, though, so whatever caused it is too far away to be an immediate threat."
A gasp exploded from Ken's station. The nativagor's fingers flew over his keys, bringing up data and images and plots, and his eyes grew ever wider as he stared at the light codes. "Oh . . ." His voice shook even as he uttered that single syllable. "Oh no . . ."
"Ken?" Jennifer asked, then ordered: "Report."
"That flash," he began shakily, then composed himself as best he could. "That flash was our message missile. It didn't make it. The —" his voice broke again, then resumed: "The intercept must have knocked it out. That thermal flash had to be a kinetic kill."
"You're sure?" Jennifer demanded.
"Positive," Ken replied. "We stopped getting deadman pings from the missile at right about the same time."
Torra covered its three eyes with one hand apiece, and contracted its torso. "How the hell," it conjured up the human expression, "Are we going to convince Sol of our intentions now?"
"Get a grip, Lieutenant," Jennifer said sternly. "We knew going into this that we might have to fight our way out of the Sol system too. We're already planning to make transit at speed, and that'll give Sol's Gate Guard and Second Guard less time to acquire firing solutions on us."
Torra twitched with the instinctive fear of a herd animal. "And they'll probably think we're the first spacecraft in a Sirian raiding force, and blow us up before they even get a good look at us!"
The baleful glare Lt. Colonel Doe leveled upon her weapons officer could have pierced stone, but the Centaurian didn't recognize it. Ken did, though. He figured he'd better intervene before the situation got ugly. "Torra. Listen to me. You've got to focus on now. Concentrate on staying alive right now, not forty-six-and-a-half hours from now. There's plenty of things that can go wrong between now and then, and we'll need your attention for all of them if we're going survive this."
Torra still twitched, but some of its panic had subsided.
"It's okay," Ken continued, "We're going to make it. You have to believe that."
Torra closed its eyes and took four simultaneous deep breaths. Then it pointed an eye stalk at Colonel Doe and said with the mouth closest to her, "Sorry ma'am."
"All right," Jennifer returned her gaze to Ken as though nothing had happened, "Obviously this fighter means business. We're gonna need as much speed as we can get before it closes to short weapons range. If its fuel situation is so tight that it only accelerated to two permil, it might not be able to do a rendezvous-intercept with us, and in that case the faster we're going the harder a target we'll be to lock on to."
Ken nodded grimly. "So we keep on accelerating toward it as long as we possibly can."
A high relative speed also meant any weapons which did hit Mercurand would be traveling that much faster and hit that much harder, Torra knew. But it kept this thought to itself.
Ken looked at his plot again, and counted the hours until their earliest possible intercept. "I think I need another meal bar."
Ken managed to sleep for an hour or two, somehow, in the sixteen-plus hours that followed. Even lying flat on his back, it took effort just to breathe in 2g. Compared with the normal 0.8g or 1g most spacecraft cruised at, it was like trying to sleep with another one of himself sitting on top of him. Sure, he'd experienced a sustained 2g before, in the Deployers he'd served aboard — but they only throttled up to 2g in condition-red combat situations, which never lasted longer than an hour. The only time he'd had to sleep in 2g before was in his cadet years, in a groundside centrifuge designed to give its trainees a worst-case scenario; he'd hated it just as much then as he did it now.
Jennifer might have been even worse off. She'd managed to snatch a few cat naps, but couldn't fall completely asleep, and even a non-human like Torra Zorra could make out the strain in her face. Well . . . maybe that was just what 2g did to a human's facial skin when that human was trying to relax, bun then again, Torra had seen her pop extra stimulants while Ken was looking the other way.
Going to the bathroom in 2g had been an even worse ordeal for both of them. The commode was designed to be usable in a wide variety of conditions, including zero gee and varying thrust, which meant it wasn't particularly well-suited to any one condition. In gravity this strong, the suction-sealed seat was that much harder to sit on squarely, and its tiny waste hole that much harder to keep proper position over. Holding the vacuum hose at the wrong angle would mean liquid couldn't go all the way through it — or, worse, would flow the wrong way.
"Coming up on point beta," Ken announced. "Preparing for turnaround."
"What's our relative vector with the fighter?" Jennifer asked.
"Closing at twenty-six hundred klicks per second," Torra replied, "Dead on with zero proper motion. It hasn't accelerated since its initial burnout."
"Twenty-six hundred," the Lieutenant Colonel mumbled half-audibly. "Nine — no, eight-and-two-thirds permil." She turned to Ken. "We need more speed. Keep our nose pointed toward it and our engine on full."
Ken glanced at his displays almost frantically. "What? No!"
"What do you mean 'no'?!" Colonel Doe snapped.
Ken explained, urgently, "We have to make a long sweeping turn in order to hit the center of the Sirius/Sol hyper hole at speed."
"And?" Jennifer asked impatiently.
"When we start that turn," Ken continued, "We can't be going any faster than one permil, or our turn'll be too wide and we'll miss the hole. We're less than ninety-eight million klicks from point gamma, the point at which we have to start the turn. And our speed's up to six-and-two-thirds permil. If we're going to have any chance of hitting the mark, we have to start decelerating now."
Jennifer let out a grunt, and pinched the bridge of her nose. "Dammit. All right, all right. Make turnaround."
"Flipping over," Ken called out, pulling the throttle lever back to idle and pressing the pre-programmed blinking button on his side panel. The engine's hum died away, as did the sensation of weight, then the room began to revolve around them as the dim stars on their camera displays began scrolling past. It was a gentle, measured pitchover, far removed from the frenetic tempest of their earlier evasive maneuvering, and thirty seconds went by before their nose settled into position facing the direction they'd come. "Throttling back up to two gee," Ken intoned as he pressed his throttle level forward again, and their oppressive doubled weight returned.
"Torra?" the Colonel turned to the Centaurian tactical station.
"Yes, ma'am?" her weapons officer replied.
"If the fighter keeps on coasting like it's doing now, what will our relative speed be when it intercepts us?"
Torra didn't need to punch up any numbers. This particular figure had been first and foremost on its tactical display since the fighter's engine had shut down, and had already taken Ken's turnaround into account. "Seven point one permil."
She sighed. "Which means if it decides to brake to a halt relative to its launching platform, which it would have had to do anyway — fuel shortage or no fuel shortage — our intercept speed would drop to only five permil. Its targeting solutions are going to be pretty damn good at that speed."
Torra continued her thought, "And if it decides to not only brake to a stop, but to accelerate back toward its launching platform, our intercept speed would be even lower."
Jennifer closed her eyes. "Well," she said, then after a pregnant pause, "Luck was with us when we stormed the gate. Let's just hope it holds out."
Their luck did hold out, at least a little. Six hours later, when the fighter had closed to a scant three million kilometers range, it still hadn't launched any cruise missiles. Nor had its engine flared back into life, which left its relative speed still at a nice high 7.2 permil; but that could change. There was still half an hour or so to go before they'd pass each other, more than enough time for its 100g engine to completely neutralize Mercurand's speed advantage.
The relentless 2g of their deceleration was taking its toll even on Torra now, lockable muscles or not. Twitches of fatigue played havoc with its arms and tentacle-fingers nearly every time it moved them. It had to switch its breathing from one mouth to another every minute or so, just to keep each lung from tiring out. It could only imagine how awful it must be for the two humans right now.
And still, it never took an eye off the closing target blip on its tactical display. Only 2.8 million more klicks, and they'd be in its short weapons range.
Two million more kilometers.
Half a million.
"It looks like they're not going to decelerate on us," Torra announced. "Current closing speed is still seven point one permil. Estimate short weapons range in four minutes, intercept in five-and-a-half."
"Get ready for Evasive," Jennifer told her navigator.
"I can't," Ken replied.
The two words dropped like a load of bricks. Silence gripped the Command Center as Jennifer shot him an alarmed, baleful glare.
He explained: "We need every second of deceleration we can grab if we're going to have any hope of being slow enough to make our turn. If we go evasive, or even partial evasive, our engine'll be pointed in the wrong direction and we'll miss our velocity target."
"So we're stuck as a sitting duck?" Jennifer countered. "Don't tell me we're gonna have to try to shoot that fighter."
"We couldn't even if we wanted to," Torra said with some alarm. "The slug launcher can only swivel through a few degrees. At this angle, it's pointing a full ninety degrees off target."
Jennifer thought frantically, then: "How about the comm laser?"
"Too slow," Torra told her. "Its gimbals take forever to point it where you want it to go, and even if you can get it pointed at a moving target it takes its own leisurely time charging up for a transmission burst when you tell it to 'fire.' No, without the slug launcher, I can't so much as shoot shrapnel at the fighter's missiles."
"No point defense?" Jennifer slumped. "Plague's poison, we're dead. Its solid missiles can one-shot targets with a thousand times our mass and a whole ocean of whipple armor. Even one of its frag missiles could tear a little wisp of nothing like Mercurand into steel ribbons, and it'll take far less damage than that to rupture the antimatter tank. And you're telling me," she turned back to Ken, "That we have to decelerate right down that fighter's throat."
Torra mulled over her words, then glared at its displays with all three eyes. "Ken," it began slowly, "Do we have any leeway as to exactly where we point the engine?"
Ken puzzled. "Four or five degrees tops. Why?"
Torra pressed a button for the S.I.'s attention. "S.I., can you tie our thrust vector directly into the targeting system?"
A pause, then a voice from one of the room's speakers intoned, "Yes."
"Do it," Torra instructed. Symbols flickered on its tactical display. Torra selected neutral areas of space near the fighter as practice targets, and tried out the new hookup. "Beautiful," it crooned, pointing a tentacle finger upward in approval.
"What are you doing, Lieutenant?" Jennifer asked, more curious than annoyed.
"Our engine's a synchrontron, right? And our exhaust is high-energy protons and electrons? That means the exhaust stream is a relativistic hydrogen plasma — just like what you'd shoot out of a proton cannon. You wanted a weapon we could turn to bear on that fighter? Well, we've got one."
Ken's eyes widened with amazement. "I'll . . . be . . . !"
Jennifer put her hand to her chin. "I'm trying to remember . . . there was some tactical doctrine about this. I just can't quite put my finger on it. Why is it that fighters and Deployers don't already use their exhaust for a weapon as a matter of course?"
"It's not something they ever covered at the Academy when I was in training," Torra half-apologized.
"It . . . might have to do with the 'muzzle velocity,'" Ken offered, suddenly bringing himself down from his high of elation. "The exhaust velocity of a Deployer is only about a hundred permil, and I think a fighter's exhaust velocity is only forty permil."
"Only?!" Torra asked, incredulous. "Do you have any idea how much kinetic energy that is?"
"It's not a question of kinetic energy," Ken replied, "It's a question of dispersal rate. The longer any plasma travels through vacuum, even a neutral plasma like a proton cannon burst or QC&C engine exhaust, the more it'll spread out, become less concentrated. You won't punch through armor if your impact material covers half a hectare."
"Right," Torra conceded, "That's why proton cannons accelerate their ammo to near light speed."
Ken grinned sourly. "Mercurand's feeding an awful lot of dead-weight propellant into the exhaust stream right now, just so we can approach the Heisenblatt-Sturnbridge ratio for antimatter efficiency — never mind actually hitting the ratio. The result is that our exhaust velocity is only two hundred permil."
The problem finally clicked with Torra, and the Centaurian's newfound confidence fell as abruptly as it had appeared. "That's . . . that's gonna kill the max effective range, isn't it?"
"Um . . " Torra worriedly searched for a solution. "Can we make the exhaust go faster?"
"We'd have to cut back on the propellant ratio," Ken mused. "That's gonna burn up a lot more antimatter if we're gonna sustain 2g. But if we only have to shoot the fighter with our exhaust for the three minutes it'll be in short weapons range . . . S.I.!"
"I'm listening," the wall speakers replied.
"Prepare to adjust the propellant ratio. I want you to keep us at two gee, but give us an exhaust velocity of eight six six permil." He turned to Torra and asked, "Would that be enough for a good beam?"
Torra raised a tentacle-finger in a Centaurian "Yes." It suppressed a gutteral snort, the equivalent of a Centaurian chuckle, at the exact figure. 866 permil wasn't just an arbitrary high speed, it was exactly a gamma factor of two. The exhaust beam would have exactly as much kinetic energy as its own rest mass, exactly as much energy as if it had all undergone matter-antimatter annihilation.
"Eight six six permil exhaust velocity," Ken confirmed. "I know we'll be consuming antimatter at a prohibitive rate," he reassured the S.I., "But I only intend to sustain it for a couple of minutes. Switch to the higher exhaust velocity mixture on my mark."
"Confirmed," the S.I. replied. "It will take approximately five seconds for the change in propellant ratio to complete once it's begun."
"Wait," Jennifer asked, "Does that fighter have a magnetic protection field?"
"Yes," Torra said. "It's been throwing up auroras from the stellar wind for at least the last ten minutes."
She shook her head. "Then your exhaust beam won't have a chance of penetrating its armor."
"It doesn't have to," Torra replied. "In fact, I'm counting on their magnetic field. That big a shower of charged particles is going to play havoc with their radar."
Jennifer narrowed her eyes. "I've been on the receiving end of quite a few proton cannon hits, Lieutenant, and none of them has blinded my Deployer's radar for more than a few milliseconds."
"But a proton cannon burst isn't continuous," Torra pointed out.
"So in order to pull this off," Jennifer figured, "You're going to have to keep the exhaust stream aimed precisely at the fighter the entire time we're within short weapons range of it, without the beam straying off target even for a fraction of a second?"
"Yes," Torra acknowledged.
"And if we blind the fighter while it's at the outer edge of short weapons range, and it decides to go to evasive maneuvering at that moment? We'll be two hundred thousand klicks apart. The round trip time for our radar will be 1.3 seconds at that range. Even its thermal blip'll be two-thirds of a second out-of-date. Even if they only pull a 10g evasive to save on fuel, they'll always be at least 50 meters away from wherever you last expected them to be. Unless you can predict the future, there's no way you'll be able to keep the exhaust stream on target."
"It's still better than nothing," Torra insisted.
"No it isn't," Jennifer retorted. "The moment they know we can blind them, they're going to wait for their radar picture to clear and fire everything they've got at us the moment they achieve weapons lock. But," she grinned and her eye twinkled, "We could always hold our fire 'til they got closer, in the hope that they don't want to waste ammo at the far end of short weapons range. We can't pull more than 2g and they know it; if we could, we'd have done so already and avoided an intercept entirely. So they'll know we can't turn tail and run."
"That's a hell of a chance to take," Ken said.
"I don't see that we have a lot of options," the Lieutenant Colonel replied.
The whole time Torra had had one of its eyes on Jennifer, another had been glaring at its tactical plot. Now, Torra twitched in fear, and called out, "Thirty seconds to short weapons range!"
"Steady course," Jennifer said, switching to the stern Commander's voice that let everyone know she'd made up her mind. "Hold all action until the range is down to one hundred thousand klicks."
Torra suppressed its nervous twitching as best it could. "Yes, ma'am."
She thought for a second about her last order, then asked: "We have lit them up with radar already, haven't we? So they won't notice anything new when we acquire a weapons lock?"
"Yes," Torra answered, "We've been exchanging radar hits with them ever since they launched twenty-eight hours ago. They've got us locked up tighter than the inside of a QC&C cell. Fifteen seconds to short weapons range . . . Ten seconds . . . Five . . . Two hundred thousand klicks! Short weapons range and closing." Torra gazed in near-desperation at the plot for several agonizing seconds. Then: "No weapons fire yet!"
"Keep us steady, both of you," Jennifer admonished them, pointing a finger at her nav display with a hand that looked frozen in stone.
"One hundred eighty thousand klicks," Torra called out. Though they were technically accelerating away from their adversary, their forward momentum far outweighed the pale braking force of their 2g engine. It would take almost a full day to come to a stop, if they'd wanted to stop. They hurtled onward like a runaway freight train — a freight train crossing half the width of Australia every second.
"One hundred sixty thousand klicks," Torra said. "Still no weapons fire detected."
"One hundred forty thousand," Torra said nine seconds later.
"Damn," Ken muttered, his voice shaky, "I hate playing chicken."
"One hundred twenty thousand," Torra intoned, accidentally speaking out of two mouths at once from sheer nervousness.
"Get ready," the Commander ordered.
"S.I.," Ken blurted, "Switch mixture!"
"Reducing propellant ratio," the speakers replied with unseemly calm. The steady 2g pressing them into their Centaurian station and human seatcouches never flinched, but the hum from the synchrotron-engine below them climbed in pitch and got noticeably quieter. They were now throwing hydrogen out their tailpipe at only a tenth the rate they were a moment ago, but each gram of hydrogen flew outward with ten times the earlier momentum, turning their exhaust into a plasma beam every bit as destructive as a proton cannon.
"One hundred thousand!" Torra barked.
"Light 'em up, Lieutenant!" Jennifer ordered.
With a combined sense of dread and relief, Torra pressed the stud that sent targeting-driven commands to Mercurand's axis control. The spacecraft nudged itself ever-so-slightly, until the exhaust stream that had passed near the Sirian fighter now pointed directly at it. Less than a second later, the telltale signs from the fighter were unmistakable. "Direct hit! Look at that aurora! No radar receiver ever built could see through that!"
"Keep it painted!" the Lieutenant Colonel insisted.
"Slug launches!" Torra called out. "Three of them. They're way off target, though."
"Have they gone to evasive?" Ken asked.
"No," Torra glared at its plot in puzzlement. "They haven't even throttled up."
To their great surprise, the S.I.'s voice came over the speakers without being prompted: "The fighter's S.I. hasn't digested the new data."
"Huh?" Jennifer blurted, taking a second or two to realize that it was the S.I. that was speaking. An S.I. was designed to respond to it's user's wishes, not to spend computing cycles mulling over arbitrary problems. She could count the number of times an S.I. had volunteered information, without its being asked, on the fingers of one hand.
"Eighty thousand klicks!" Torra called out, following standard procedure.
The speakers continued, "Fighter S.I.'s have a package of pre-programmed contingencies to speed their decisionmamking. Any contingency not covered requires analysis, which is an NP-complete operation. It may take some time for it to consider evasive maneuvering as an option."
"Well," Jennifer said, regaining her composure, "Let's hope the fighter doesn't figure out that option before we're well past it."
Past it, Ken thought. Then a look of horror blossomed on his face. "Ma'am," he cleared his throat, and spoke with slow calm, "What do you intend for us to do when we're past the fighter and pulling away from it?"
"Keep it blinded, of course," Jennifer said. "Swing around and —" She stopped cold in mid-sentence.
Ken shook his head slowly. She'd figured it out. They couldn't swing around. They had to keep their thrust vector pointed directly away from point gamma without let-up. That meant they had to keep their exhaust pointed in the direction they were travelling, and that meant they couldn't keep their improvised weapon pointed at the fighter once they'd passed it.
"Sixty thousand klicks!" Torra called out into the silence. Why had the Commander stopped speaking? She was talking about swinging ar— . . . It figured out the conundrum for itself and twiched in fear.
"Options!" Jennifer barked, almost in desperation.
Torra glanced at every display surrounding it, feeling Jennifer's desperation duplicated inside itself despite the species barrier. There had to be something they could do, some way to neutralize the threat the fighter would pose once they passed it and its radar cleared. Mercurand was no Deployer; the tool set at Torra's disposal was limited to radar, the target tracking system, the exhaust "gun" currently focused on the fighter, and the —
Torra flipped a switch and pressed a hard button. A barely-perceptible click and clank, muffled by more than one intervening wall within the spacecraft, echoed in their ears. The two humans glanced at Torra in puzzlement, to which the Centaurian announced, "Slug loaded!"
Ken answered out of instinct, "We can't change headi—"
"We can hit the fighter as we pass it," Torra explained. "It's on course to pass us on our zero eight zero. Rolling right to bring the launcher to bear."
At a touch from Torra's tentacle-fingers, the room turned clockwise like a slow carousel. Ken's stomach churned in surprise. Axis rotations — even just rolling, which didn't affect their thrust vector — were the exclusive purview of the pilot. It should have been impossible for any hand but Ken's to turn the spacecraft at this moment. Torra had tied the targeting system into the thrust axes, true, but that should only have afffected pitch and yaw, not roll. Perhaps the S.I. had interpreted the Centaurian's instructions more liberally than that, and had shared control over every axis in the spacecraft between Torra's station and Ken's.
"Forty thousand klicks!" Torra called out, just as the room stopped spinning. "Slug launcher in line. Computing firing solution." It noted their anticipated separation when they flew past each other — less than a thousand klicks, a hair's breadth in spaceflight — and flinched involuntarily when it discovered how rapidly the firing angle would be changing at that moment. The target would only be in the slug launcher's firing arc for eighty milliseconds, yet the slug would take over three hundred milliseconds to cross the gap between them! The targeting software would have to fire automatically when the target was still well outside the firing arc, and aim for the precise point where the fighter would be when the slug arrived. And hope that the fighter didn't fire up its engine any time in between. The numbers congealed on one of its displays, and Torra locked it in.
"Twenty thousand klicks!" Torra called out. Then, five seconds later: "Ten thousand! Auto-engage!" They were now committed to firing the first — and, if they were very lucky, the only — shot of this engagement.
Then, as it had yesterday when they'd first entered Sirian space, the room lurched to the left and the dim bang! of the mass driver flicked their ears. A one-kilogram slug, solid steel this time, raced out of its shallow hole and accelerated to ten permil on the crest of the launcher's magnetic focuser.
Less than two seconds prior, the Sirian fighter that was the slug's target emerged from the shower of charged particles that had been harassing it. Its vision finally cleared, and it at last reacquired a solid radar image of its prey — and of a tiny chunk of material hurtling directly toward it at 12.2 permil relative. It was too late to power up the main engine; too late even to return fire. The lump of inbound metal shrugged aside the fighter's magnetic protection field and slammed dead-center into the outermost layer of whipple armor with the force of nearly 1500 tonnes of TNT. The projectile splashed through layer after layer of progressively thicker steel plates, each time losing a little of its own outsides to superheated plasma, until at last there were no more layers of armor to penetrate and the remaining meteor slanted mercilessly through the fighter's guts. The light-hydrogen fuel tank lay first along its trajectory. Where the sun-hot slug plowed through cryogenic liquid hydrogen, the ultra-cold liquid flashed to a gas, increasing its pressure by orders of magnitude. Even partly empty, the tank wasn't strong enough to withstand that much gas pressure. Safety valves on all sides of the tank popped open, spewing gaseous and still-liquid hydrogen harmlessly into space so as to prevent the whole tank from bursting. The slug passed out of the light-hydrogen tank and though the wires and steel at the fighter's core before it continued on into the heavy-hydrogen tank; but one of the bundles of wires it hit along the way contained both the main bus and the backup bus for radar control. A year of war had taught a harsh lesson in fragility to fighter engineers, and now every fighter's innards were heavily compartmentalized, and every system that could be made redundant was made reduntant, to prevent a single shot such as this one from cripping it. In this case, though, both of the redundant radar control buses happened to cross over one another right along the slug's path. Its designers had been given a mandate of simple redundancy, and had made sure the letter of the requirements had been adhered to; had they been more conscientious of the purpose behind the redundancy, they might have been more careful about letting the backup bus lie so close to the main bus before signing off on the design and handing it over to the assemblers.
The fighter's radar still worked, but the data couldn't reach its targeting systems until an internal repair robot found the break and fixed one of the control buses. Without radar data, targeting could track the enemy's position in the sky from its thermal emissions, but had no accurate way to determine distance.
"Did we get 'im?" Jennifer demanded.
"Yeah," Torra said, "Huge thermal telltale there. From the size of that flash, either we hit it, or it decided to set off a small nuke. It also looks to be venting some fuel."
Jennifer was about to ask if the fighter was returning fire, but Torra's tactical display flared with angry red data before she could open her mouth. "Multiple slug launches!" the Centaurian called out. "They're . . . they're missing us! All of them! Every last one of 'em is off target. I don't understand . . . it's like the fighter doesn't have a radar lock on us. But we're still taking radar hits from it — in fact, its radar is lighting us up like a nighttime hunting party."
"Hah!" Jennifer cheered. "I'll bet we wrecked its targeting."
Torra stiffened as a new report clamored for its attention. "The target's changing course."
"Is it headed back for us?" Jennifer asked.
Torra pointed an eye straight at its course-projection display. A dotted line, punctuated with tiny arrow heads, swerved and shifted on the display, a computer-generated estimate of where the fighter was likely to be headed. But Torra didn't need it; the thrust vector arrow, overlaid on the fighter's blip, faced unflinchingly to one side. This was a minor course adjustment, not the start of a course reversal. "No," the Centaurian replied. It watched the data settle, then saw a new code: "It's stopped accelerating. Its new course'll bring it right to the Sirius/HC hyper hole at two permil."
Jennifer wrinkled her brow. "Oh no. They might be redeploying it for some sort of 'counterattack,' in reprisal for Mercurand's incursion."
"Could be," Ken said, "But personally, I'd guess that they're just doing it to save fuel. That fighter can probably be repaired and refuelled at either Gate Guard. If they wanted to go back to the Sol Gate Guard, they'd have to brake to a halt, then accelerate back the way they came, then brake again when they got there. Getting to their HC Gate Guard just requires them to make a tiny course change — their course to intercept us was already taking 'em pretty close to the Sirius/HC hyper hole to begin with — and then brake just once, at the end. Depending on how soon they needed that fighter back in action, the delta-vee savings could be enormous. You did suggest earlier that that fighter might be running on a less-than-full fuel loadout; maybe it vented enough fuel from our slug hit to lose the return option."
"I'm not seeing any more slug launches," Torra announced. "The fighter might've been shooting lasers or proton cannons at us too, but if it did they all missed." It moved an eye from its consoles to look, almost triumphantly, at its human comrades. "And its receding velocity is too high to hit us with short-range missiles."
"Well, that is good news," Jennifer said, taking the determined edge out of her voice for the first time in days. "Unless we run into some incredibly bad luck in the next minute or two . . . Mercurand has just survived a point-blank encounter with a full-sized enemy fighter. Frankly, that's pretty damned amazing."
Ken glanced at his copy of the Tactical display to watch the blip fall away from them, then returned his attention to their course, and their ultimate intercept with the Sirius/Sol hyper hole. "Let's just hope we don't have to do it again."
Surprisingly, the next twenty-five-and-a-half hours passed without incident. Mercurand reached point gamma and started its powered turn right on schedule. In six-and-a-half hours — assuming their experimental antimatter synchrotron engine didn't quit on them — their powered turn would end and they'd be one light-second inbound to the Sirius/Sol hyper hole, and the two . . . no, make that three enormous asteroid bases stationed next to it. Ken had been waiting for the next shoe to drop the whole time, for another fighter or a cruise missile to come barreling toward them out of nowhere; and sometimes he wondered whether it wouldn't have been less stressful to have had some emergency to focus on. Sure, he'd had ample opportunity to sleep, and even the relentless 2g of their deceleration couldn't overcome that much fatigue. But his sleep was fitful, and could only come in short bursts, and each time he awoke nearly as tired as he felt before he'd passed out.
"So," Ken said, glaring somberly at his course display, "The Sirians have at least been nice enough to let us get this close to their back door without sending any more fighters after us. Do we actually have any plans for surviving their Gate Guard and Second Guard?"
"Well," Torra offered, "I've heard stories from back at the start of the War about Sol's chief diplomat — I believe his name was . . . Carter, wasn't it?"
"I heard that same story too," Jennifer answered. "James Carter, flying in a plain limo armed only with a few thermal decoys, flew right into the jaws of the same Gate Guard we're headed for now, and managed to survive."
Ken countered, "Carter had an option we don't. He was able to put in a call to Sol for help. Sol knew approximately when he was going to pass through the gauntlet, so they were able to send some fighters through at just the right moment to distract the Sirians. This was also right at the beginning of hostilities, so the Gate Guard crew was way underprepared — oh, and they didn't have a Second Guard at the time either. And while he did survive the trip, his limo got knocked off kilter in mid-transit and ended up being sliced in half by boundary shear."
Torra twitched. If Mercurand got sliced in half, it would almost certainly bisect their antihydrogen tank, releasing nearly a hundred tonnes of antimatter from containment. Some of their remains might avoid the explanding cloud of doom, but the gamma rays blasting out from whatever atoms of the spacecraft didn't avoid the antihydrogen would easily vaporize anything left over.
Jennifer nodded somberly. "Yeah. About the only thing we have going for us is that their Gate Guard and Second Guard are designed around stopping intruders from entering the system from Sol. If they're anything like our Gate Guards and Second Guards, their weapons are aimed at the hyper hole, not back toward any potential targets approaching the hyper hole from in-system."
Ken grimaced. "Except there are two Second Guards, one facing the peacetime-arrival side of the hole and one facing the peacetime-departure side. It's the peacetime-departure side of the hole that we're headed for ourselves. Sure, the Second Guard on the peacetime-departure side is going to be pointing its weapons away from us, but the Second Guard on the peacetime-arrival side is going to be pointing its weapons almost directly at us. When we're lined up exactly with the hole for transit, the hole will be between us and the peacetime-arrival Second Guard, but until then it's going to have a clear line-of-sight on us. There'd be nothing preventing the peacetime-arrival Second Guard from shooting past the hole directly at us."
"What if —" Torra began, then stopped itself. "No no no, bad idea."
"What was it you were thinking, Lieutenant?" the Colonel asked.
Torra held up one hand in a Centaurian "No," visibly twitching. "It's a monumentally dangerous idea."
Jennifer put her hands on her hips as best she could in 2g. "We don't appear to have a lot of options at this point."
"No no," Torra countered, an edge of panic starting to creep into its mien, "I'm sorry I mentioned —"
"Spill it!" she barked. "That's an order!"
"Well," Torra tried, in vain, to compose itself, "I was thinking, if they're going to hold their fire 'til we're in short weapons range, we could wait until we're less than four hundred thousand klicks away and then . . ." it twitched ". . . and then we could tell them we're carrying antihydrogen."
Jennifer half-glowered, half-smirked. "I see why you thought it was a bad idea."
Ken was deep in thought. "That might actually work. If we're headed right for their position at one permil, they'd know that if they destroyed us, at least some debris from our remains might hit them. They're armored against plain old kinetic impacts, but I doubt they know what would happen if they got hit by a cloud of antimatter."
"We'd also provoke an international incident," Jennifer countered. "You know what our orders are. If anyone finds out about our antimatter load, CN Leonis can and will eventually get wind of it, and you know what a bunch of paranoid Centaurians they are." She barely glanced at Torra when she said "Centaurians." "They could very well upgrade their opinion of Human-Centauri from 'minor annoyance' to 'dire threat next door,' because they'll know — not just suspect, know — that Human-Centauri is both willing and able to send a load of antimatter into its enemy's back yard."
"Begging the Colonel's pardon," Ken noted, "But I thought our orders were to hide our antimatter because of what the enemy would do to Mercurand if they found out, not because of what new offensive one of our neighbors might mount against Human-Centauri if they found out."
"Both," Jennifer said. "And even if there were no strategic implications, it would ruin any chance we'd have of leaving Sol space in peace. Once Sirius told Sol about our antimatter, Sol would blow us apart the moment we're at a safe distance."
"I don't think they would tell Sol about our antimatter," Ken countered. "Think about it. Sol is a much bigger threat to them than we are. They've gotta be thinking that if Sol thinks we're an ordinary spacecraft that isn't carrying antimatter, they might just open fire the instant we poke our nose through the hyper hole. At that kind of point-blank range, the blast from all that antimatter might have devastating consequences for their Gate Guard. It wouldn't be enough to take down the entire Gate Guard, of course — the thing's anchored in a hundred klick chunk of rock, for goodness' sake — but it could seriously mess with its more exposed systems, maybe even slag some of their radar and lidar arrays."
"So we'd die after making transit, instead of before," Torra said.
"I didn't say that's what would happen," Ken replied, "I said that's what Sirius might hope would happen. In which case, if they didn't tell Sol about us, we'd be no worse off against Sol's defenses than we are right now."
Torra pointed an eye at him and said, flatly, "And right now, we're really, really bad off against Sol's defenses. As in, they're not going to be caught flat-footed like the Sirius/HC Gate Guard was. Sirius hasn't taken a purely defensive posture like Human-Centauri has. They have made probing attacks into Sol space, which means Sol's Gate Guard and Second Guard will be on a hair-trigger alert pretty much all the time."
"You're thinking like a Centaurian," Jennifer chided. "Humans don't have your level of paranoia. Yes, the Sirians have made probing attacks through their hyper hole with Sol, but our best intelligence indicates that the last attack was over two months ago. That means there's a damn good chance Sol has let its guard down. They have more than enough fighter deployers to cover the routes between their hyper holes and any-and-all of their valuable targets, and they know it. They can afford to let one or two high-speed intruders slip through. And low-speed intruders, well, their Gate Guard can just pick those off as they appear, flat-footed or not."
"Still," Ken cautioned, "We can't count on them being totally out to lunch."
"Agreed," Jennifer said. "All right then, we announce the existence of our antimatter when we're 5 minutes away from their Gate Guard's short weapons range. We'll worry about the international repercussion when we get back home two decades from now. Then we make our dive through the Sirius/Sol hyper hole exactly the same as we did with the HC/Sirius hyper hole two days ago."
"Ooh," Ken said, "There's something else we'd better make sure of. If we're going to make an at-speed transit, there'd better not be any debris in front of the hole."
Torra tilted slightly away from Ken in a Centaurian shrug. "Our intelligence data says they don't have anything like our Rock Pile . . ." it checked a long-range radar display ". . . And the only echoes we've gotten back from the area are the Gate Guard and the two Second Guards."
"They may not have intentionally placed any debris in front of the hole," Ken worried, "But unless they've been making recent offensives against Sol through the peacetime-departure side of the hole, they won't have made any effort to keep accidental debris from accumulating there. Even a pebble-sized bit of trash, if it crashed into us at a full permil . . ."
"Hmmm," Torra hummed in two different pitches with two mouths at once. "S.I.?"
"I'm listening," the speakers replied.
"Can we pick out small amounts of debris from a thermal image?"
"Looking up the procedure," the speakers answered. Then, a moment later: "Yes. It will require a long exposure time at maximum magnification."
"Then get started now," Torra told it. "Find out if there's so much as a gram of dust in front of the peacetime-departure side of the Sirius/Sol hyper hole."
"Commencing infrared astrophotography," the speakers said. "Exposure time one-half hour. Please refrain from any unscheduled maneuvering during this time."
Torra almost snorted at that. A half-decent infrared telescope could have snapped a photo in half a second that showed every dust grain within ten thousand klicks of the hole, in enough detail to give each grain its own name and serial number. Then again, a half-decent infrared telescope would have been bigger than the already-humongous comm laser docked in Mercurand's flank. No way did they have the mass allowance to spare for detectors even a tenth that heavy.
Half an hour later, when their tail had swung through seven degrees of their powered turn, they had their answer. Most of the expected dust and debris had been swept clear from the area. Whoever had dropped off the fighter that had gone after them yesterday had probably been the reason; even at low speeds, a dust-free vacuum was a lot nicer on spacecraft hulls, and the Gate Guard's flotilla of sweepers might have cleaned up local space for its arrival as a matter of standard procedure. But a few tiny, ominous flecks of material still danced in the ultra-low gravity between the Gate Guard and the Second Guards.
Ken frowned at the data, rubbing the fatigue from his eyes. "Looks like we'll have to take our chances. We do have one whipple layer protecting the hull, at least."
The hours crept by with painful slowness. Each hour traced out another million kilometers, and fourteen degrees, along their 90-degree arc. Each brought them that much closer to their target, and to the asteroid-sized engines of death that guarded it. And each pressed down on them with the same 2g that had hammered them for two days. Radar hits from the approaching Gate Guard and Second Guard lit them up again and again, but not a single long-ranged weapon ushered forth to greet them.
Finally, with 11 minutes to go before the end of their powered turn, when the hole and its guards lay a scant half-million kilometers away, Jennifer picked up her microphone. "S.I.?"
"Prepare to send the Chairholder's message again, this time both the audio and video portions. I want them on a general radio broadcast aimed toward the Sirian Gate Guard and Second Guards. Put it on as many common frequencies as we can, doppler-compensated for our approach speed. And append the following audio recording onto the end."
She keyed her mike, and began recording: "You've just heard a plea from our Chairholder, informing you that we're not on a military mission and that this spacecraft is an experimental starship design. What the Chairholder didn't tell you about was what it is that makes this starship's design experimental. You may have noticed, if you'd cared to look, that our exhaust consists not of helium but of hydrogen. Our engine isn't powered by proton-deuteron hot fusion, or by deuteron QC&C fusion, or by two-stage QC&C fusion, or by any kind of fusion at all. We," she spaced out her words for emphasis, "Are powered. By. Antimatter. Our main fuel tank contains nearly a hundred tonnes of antihydrogen, carefully balanced in a metastable state inside a non-magnetic containment tank. If any of your weapons hit us, it's a near certainty that this containment will breach, resulting in the annihilation of most of this antimatter with the material of our hull. I don't have to tell you what kind of radiation storm will be unleashed if this annihilation takes place. Furthermore, I remind you that although most of the antimatter will probably annihilate with our hull, some will almost certainly escape and spread out in a cloud of neutrally-charged — I say again, neutrally-charged — antihydrogen. Since the center of mass of this expanding antihydrogen cloud will have the same speed and course as this spacecraft currently does, at least some of this expanding cloud will eventually make its way to your Gate Guard and Second Guard facilities themselves. Personally, I don't know how well your armor would hold up to such a barrage, but I do know that it will pass right through any magnetic protection fields you could place in its path."
She paused, still recording, to let her point sink in. Then: "As our Chairholder has told you, our immediate intention is to transit peacefully through the Sirius/Sol hyper hole and leave your space. In fact, you can verify right now that our powered turn will put us dead-center on course for the peacetime-departure side of the hole when we're three hundred thousand klicks away. But if you attack us, we will detect your weapons fire a few seconds before it reaches us, and we will use those seconds to put ourselves on a collision course with either your Gate Guard or your near-side Second Guard. Even if you reduce us to vapor, there's no way your asteroid-mounted installations can dodge that much antimatter. The consequences will be just as dire for you as they will be for us. Let us pass, and we won't pose any danger to you. Mercurand out."
She released the recording stud. "All right, transmit."
"Sending," the speakers answered. A tiny blip on their panels told them power was being fed to the high-gain radio antenna. It stayed on for three minutes. Not because the messages were being played in real time; they existed only as compressed data packets. The three minute transmit time was because of all the error-correcting codes and rebroadcasts necessary to ensure that all of their data would arrive glitch-free.
The Colonel addressed her miniature crew: "Condition red, people."
Torra pointed one of its eyes directly at its thermal imaging plot, scrutinizing it for any hint of new engine activity near the hyper hole. After some seconds of nothing changing, the Centaurian announced, "Well . . . our little revelation didn't convince them to blow us away with missiles before we reach short weapons range, at least."
"That was a risk," the Colonel acknowledged. "They could have figured that our debris cloud might be rarefied enough by the time it reaches them that the amount of antimatter striking their surfaces would be minimal. Plague's poison, it might actually be minimal; space gas cloud dynamics isn't exactly one of my strong suits. Let's just keep hoping they want to err on the side of caution."
Ken shrugged in his seatcouch. "Or our message might have had no effect whatsoever, and they're still waiting for us to get in short weapons range before they pounce."
Torra twitched. "Commander, did you really mean what you said about putting us on a collision course?"
"If they fire on us, yes. But," she grinned slightly, "That doesn't mean we won't also go to evasive once we're on that course. If any of the things they fire at us are missiles, it'll give 'em a chance to send abort commands. Then, if we survive the salvo, we can go back on course for the hyper hole. They'll know we mean business, but they'll also know we're not suicidal."
Unless that convinces them we're an even bigger threat, Torra thought. It fought to hold down its rising sense of panic. Focus, it told itself. Focus on your nav summary display. Focus on the little base-ten number in the corner that showed your distance to the hyper hole. It counted down, ever-so-slowly, toward 300 000 kilometers. No transmissions arrived. No engine telltales flared to life, fighter or missile or otherwise. The radar coming from the Gate Guard and near-side Second Guard continued to paint Mercurand's hull just as before. Good. All good so far. So far. The Centaurian kept the same eye pointed, fixed, at its tactical plot, and stared with such intensity that it feared the eye might freeze in place.
At last, less than seventeen minutes from intercept with the hole, they crossed the one-light-second threshold that marked the outermost envelope for short-ranged weapons.
"Three hundred thousand klicks!" Ken called out. "Powered turn complete, going idle." The relentless 2g thrust they'd almost grown accustomed to finally abated; the twin blessing and curse of weightlessness once again embraced them.
"No new activity," Torra replied.
Jennifer frowned. "They might be waiting for us to reach the two hundred thousand klick mark, for better targeting."
"We'll know in five-and-a-half minutes," Ken said.
Torra had already configured its surround-displays so that the distance countdown was exactly 120 degrees away from its main tactical summary. That way, it could keep keep both of them pinned dead-center in two eyes' fields of view, without having to rotate its eye turret back-and-forth.
It was one of the longest five-and-a-half minutes Torra had ever endured, yet at the end:
"Two hundred thousand klicks!" Ken called out, to make it official.
"Still no activity," Torra replied with almost reverent calm.
Jennifer's face widened into that same grin Torra had seen before, her grin of victory. "We're safe," she declared.
"They could still —" Torra began, then stopped itself as the Colonel shook her head.
"If they were going to attack," she said, still grinning, "They'd have done it by now. Ken, stay dead-center on course for the hole, and don't even let them think we might hit their installations. Let's not make them panic."
"Aye, ma'am," Ken replied with a matching sense of relief.
The Colonel's victory grin vanished. "Now then. Eleven minutes from now we make transit into Sol space. I want us to hit our marks exactly as well then as we did when we entered this star system two days ago. I know you're both tired, I'm tired too, but we've all got to focus. Just like last time, we've got to go to two-gee partial evasive the instant we're through the hole, and shoot down any incoming missiles in the ten seconds before we pass Sol's Second Guard. One second of bleary-eyed distraction could kill us all."
Of course, Torra never got bleary-eyed. Eye strain was a human condition, resulting from the need to keep the ciliary muscles in a constant state of partial contraction. Centaurians didn't have ciliary muscles — instead, the eye stalks varied their focal distance like a camera, by moving the lens closer to or farther away from the photoreceptors near the center of the turret. And all Centaurian muscles could lock in place with no exertion, including the focal distance muscles. But Torra understood the Colonel's meaning, understood the need to be as sharp as it could and at the top of its game.
Ken said, "Already got the sequence set up and running, ma'am. The instant we detect we're through the hole, partial evasive'll kick in. Assuming Sol's Second Guard is in the usual place, the S.I. will gauge which side of it is farthest off-center, and aim us for the opposite side to give us the widest berth. It'll happen faster than I can even press a button. Of course, I'll be pressing the button anyway, on the off chance the detect algorithm glitches out."
Torra asked, "Do we have any intelligence on the exact position of Sol's Gate Guard and Second Guards, relative to their side of the hole?"
Jennifer frowned and shook her head. "I don't think so. S.I.?"
The wall speakers replied, "All data on Sol's military deployment pre-date the war."
Torra made a grunting noise with two of its mouths. "I'll just have to guess where to look first, and hope the thermal-IR can pick out their positions fast enough to know where to point our radar. At least we can be reasonably sure their two Second Guards will be on direct lines from the two sides of the hyper hole. Their main Gate Guard could be off at any angle, though. If I don't guess right, we'll have to wait for a radar-sweep of the entire sky before we get distance data, and by then it might be too late."
Ken snorted. "I just had a thought. What if they've come up with a way to extend an ARA field over an entire Gate Guard?"
Torra twitched. "Don't scare me like that!"
Jennifer said, "If we worry about every secret weapon Sol might have developed since the war began, we'll paralyze ourselves. We have enough to worry about with what we know they can throw at us."
"Which is quite a lot," Torra said, keeping its voice steady. "My intel display shows that the Sol/Sirius Gate Guard sports over two hundred slug launchers, and an unknown but significant number of high-energy lasers. Its missile complement is downright staggering, but we'll be headed away from the Gate Guard too fast to worry about any short-ranged missiles it might launch. Remember, though, that this data's a year out of date, and Sol has almost certainly beefed the Gate Guard up even more since then."
"And the peacetime-arrival-side Second Guard?" Ken almost didn't want to ask.
Jennifer snorted. "I'll bet you anything we have zero intel on that. No nation even thought of Second Guards before the war started, and after the war started . . . well, it's like the S.I. said. All of our intel on Sol pre-dates the war. We can't even get a spy into Sirius or CN Leonis, much less Sol, and even if we did they'd never be able to get their data back to us. All we can be sure of is, Sol has the biggest military of any nation, and you can bet their Second Guards are going to reflect that."
Torra added, "And if their Second Guard is positioned to intercept the kind of high-speed transit we'll be making, straight down the perpendicular, they'll have line-of-sight though the approach path on this side of the hyper hole. Which means they'll see us coming."
Ken smirked. "Not until the last moment. You know what else is lined up straight along the perpendicular? Sirius's Second Guard. That's what's in their line-of-sight right now. In fact, it's so huge it'll take up their entire field of view — which is why we're not going straight in along the perpendicular, but at a slight angle. They won't be able to see us until we're only three thousand klicks from the hole, and at the speed we're travelling we'll cross that gap in ten seconds."
"That's ..." Torra twitched. "That's ten seconds for Sol's Second Guard to see an incoming object on a radar sweep. It's ten seconds for it to lock all those slug-launchers and lasers on us. And unless I miss my guess, Ken, it's ten seconds during which we won't be able to pull any kind of evasive, not even a partial evasive."
Ken nodded somberly. "We have to pass through a 200 meter hole at a full permil. Even the tiniest course change could make us miss the hole — or worse, turn us into a boundary shear statistic." He saw the twitches gripping all four of Torra's arms. He couldn't let the lieutenant panic. "Okay, we can't do anything about slugs or lasers, but we might be able to hold off any missiles Sol's Second Guard throws at us while we're still on this side. I can throttle the engine down to idle for the last ten seconds before the hole, and coast through. That'll let us rotate your slug launcher into position. You can load it up with one of your shrapnel packs."
Torra made a brief gutteral snort with the mouth facing away from Ken, then said, "I've had a shrapnel pack loaded for the last half hour. But remember the cycle time on the E-43. I'll get to shoot down one missile, tops, and if they send in a big salvo . . ."
Jennifer asked, "We still have chaff, right?"
Torra waggled its eye turret in a faint imitation of a human nod. "Three more salvoes. But the chaff throwers have the same problem as the slug launcher. Their cycle times mean we can only use them once per engagement. If they throw a salvo at us while we're on this side of the hole, and we fire off the flares, we won't have any chaff if the the Second Guard decides to launches missiles at us after we're on the other side."
Jennifer said, "So if it's a big salvo, we use the chaff, and if it's a small salvo, we use the shrapnel. And if they don't launch any missiles, we won't have to use either. Well . . ." she glanced at her nav plot. "Eight more minutes. That's all we have to wait."
Torra focused as best it could on the coming gauntlet through which they had to pass, determined not to panic. From time to time, Ken glanced at it, and if Torra had been better able to read human facial expressions it would have seen the nervous apprehension in Ken's eyes. Torra hardly noticed when a human was glancing at it, though; Centaurians kept an eye on everything around them at once, and instinctively expected everyone else to do the same. It took a prolonged stare to set off any social alarm bells. As far as Torra could tell, its two human companions were as deep in concentration, and focused as deeply and exclusively on their own tasks, as itself.
Seven more minutes.
Five. The S.I., showing a penchant for the obvious, announced, "Five minutes to line-of-sight."
One. The Second Guard loomed large in Torra's visual display, less than a tenth of a degree across but growing by the second. It was far smaller than the Gate Guard, and had to be: the Sirius/Sol hyper hole's slow rotation meant that this Second Guard had to apply continual station-keeping maneuvers to stay close to the hole's central exit path. These maneuvers would have been prohibitively expensive for a 140-kilometer asteroid, but even a five- or ten-kilometer rock could house more than enough firepower to blast apart several spacecraft at once.
Even unmagnified, the structures and weapon emplacements dotting the Second Guard's rocky surface were unmistakable. It grew and grew as the minute passed, but wasn't quite dead ahead. They were headed for a point a few thousand kilometers beyond it, currently obscured behind its great bulk. Its rough station-keeping meant it hardly ever lined up precisely with the dead center of the hyper hole; the side currently on the top would be much easier to swerve around than the side on the bottom. Ken had already aimed Mercurand for the Second Guard's upper limb.
Torra twitched in frightened anticipation. The waiting was worse than the actual ordeal.
Five more seconds. The Second Guard's curved surface filled the bottom half of Torra's visual display, close enough to count the buildings as they scooted past.
Then Ken spoke: "Line of sight . . . now!"
There it was! The Sirius/Sol hyper hole. At high magnification Torra could see the 200-meter disc, filled completely with a view of another Second Guard's surface. Sol's Second Guard.
And that other Second Guard, on the other side of the hyper hole 8.6 light-years away, was already painting Mercurand with radar.
The Pentagon War is continued in chapter 10.
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