Boundary

by Eric Flint

  At least the second half of the practice had gone well. If she could keep it up, she'd be ready to try real microgravity soon. They'd already tested her acceleration tolerance, which had been surprisingly high—at the same level, in fact, of trained fighter pilots. Only Colonel Hathaway had scored better.

  She wasn't looking forward to weightlessness, though. A.J. had come back from his first experience looking about three shades paler. He hadn't quite lost his lunch, but apparently it had been a near thing. Still, he'd gotten over it and done his first orbital two weeks ago.

  Joe, on the other hand, apparently hadn't even blinked when he first went weightless. Hopefully, Helen would have the same reaction.

  That reminded her—Joe should be coming back from his first orbital flight soon. She checked the time. Yes, if she hurried she could be there for the landing.

  She opened a voice channel to A.J. as she dressed. "Hey, A.J.!"

  "What's up, Doc?"

  "I'm going to go see Joe land. You coming?"

  "I'm already on my way. Meet you there. Then we can all go out to eat before it's back to the salt mines."

  "Sounds good to me."

  She finished dressing, jogged down to the parking lot, and got in her car. She was careful to keep the windows rolled up as she exited. That wasn't to ward off the late autumn chill, it was to ward off reporters. Following the announcement of the discovery and the upgrading of both Nike and Ares, news crews were always hanging around the exits.

  She let the window down after she passed the news people and headed for the landing strip, a couple of hours away. Her blond hair whipped in the breeze. The air was a little chilly, but the sensation felt good after all that time in a spacesuit.

  She had a sudden vision of driving like this on Mars, the terraformed Mars that Ares envisioned. The New Mexico landscape she was driving through was even somewhat similar to that on the Red Planet. Now wouldn't that be cool? Well, not something I'll see, but maybe three generations from now.

  Eventually she pulled through the security gate, parked in the lot, and headed for the landing area. The vastness of the dry, dusty plain shimmered in the desert sun. The landing strip, a darker ruler-straight road built to a giant's scale, seemed to waver slightly. Off to the left, the control and support buildings threw sharp shadows against the hardened soil, but their somewhat illusory coolness wouldn't allow a good view of the landing. Instead, a long, open pavilion with chairs sat not far from the control area, with a large flatscreen monitor installed in its own weatherized enclosure to one side to provide alerts and alternative views of the landing.

  About thirty people were there already. As Helen got closer, she noticed that they seemed unusually quiet. Many were standing, huddling closer to the monitor instead of watching the sky.

  "What's going on?"

  "Chinook is in trouble," A.J. answered grimly.

  Chinook was the orbital craft Joe had gone up in. "Oh, no. What's wrong?"

  "Not sure yet. They were getting funny responses from the hydraulics, and then she went into reentry blackout. We should've heard something by now, but . . ."

  "Jesus." Helen knew what that meant. The likelihood was that Chinook had disintegrated on its way down. Joe would have known maybe a few moments of panic, and then . . .

  "There she is!"

  Helen's head snapped up. High in the distance was a pinpoint of white. It moved slowly and started growing as she watched.

  "Still no communications from Chinook," one of the controllers said over the PA. "Craft is still roughly in descent path in apparently controlled glide. Not on optimal approach."

  "Mother of God," A.J. muttered, staring at something only his VRD could show him. "Chinook is on fire!"

  A moment later, A.J. tied in his enhanced feed from the multiple cameras along the glide path to the publicly visible screen that Helen and the others were watching. Instead of just a tiny dot of an approaching object, Chinook was an ominous daylight comet; a dot with a contrail of white, gray and black smoke, and tiny, grim flashes of flame-orange.

  "We have a signal!"

  A hiss of static on the PA was suddenly broken with a distorted but mostly comprehensible voice. "—trol, this is Chinook. We are in an emergency descent. Systems mal—"

  A roar of interference obscured the signal. Then: "—arginally functional. Landing gear will not deploy. Re*buzzz* foam and emergency crews. Calling on suit radio. Do you copy?"

  Helen recognized the voice as that of Major Bruce Irwin, the Chinook's pilot. His Australian accent was unmistakable.

  "Roger, Chinook, we copy. What is your fuel status, over?"

  "Tried to dump remaining fuel, no go. Still have *frrrz* percent remaining. Fire hazard definite. Suspect exterior fire."

  "Confirming exterior fire. Repeat, presence of fire visually confirmed. Can you land?"

  Major Irwin's voice held a note of dry humor. "Control, I am positive we can land. Not sure if it will be a good landing, though. Must concentrate on that part. Chinook out."

  "How the hell could he even joke about making a good landing? Obviously he won't." That came from Jackie Secord, standing on A.J.'s other side. Her hands were clenched tight to the back of the chair near her.

  "He has to," Ken Hathaway said quietly. "The oldest and clearest definition of a good landing is one you can walk away from. And if he doesn't manage that with this . . ."

  Chinook was much more clearly visible, streaming black smoke as it wobbled in towards the landing site. It was obvious that the craft was reacting sluggishly to controls, recovering from a tilt with an aching and frightening slowness.

  "Come on, come on. . . " A.J. muttered. "You're almost there. Come on, almost there . . ."

  Chinook was shedding velocity as well as altitude—that much, at least, was as everyone wanted it. The rumbling boom of its earlier transsonic passage echoed faintly across the desert.

  "Chinook now three miles downrange, speed two-fifty-two and dropping—"

  "Oh, shit."

  Something had finally come loose on the nose. Debris showered up and over, black smoke streaming across the cockpit. The damage spread as though pushed by the winds, and suddenly the cockpit seemed to disintegrate. Inky smoke spewed into the air and Chinook heeled slowly over, executing a dreamlike cartwheeling pirouette in the sky before thundering down to impact on its side, ironically directly in the center of the runway. The orbiter bounced up, spinning and shedding fragments of wing and tail everywhere, and the spectators dove for cover.

  Chinook's second landfall was squarely on the tail section, and with a whooshing roar it ignited in an orange-red-black fireball. Something had sheared through the fuel cells. Now nothing but a moving holocaust, the remains of Chinook seared their way down another several hundred yards of runway before shuddering to a flaming halt. Emergency vehicles, already scrambled, skidded to a halt around the wreckage and began trying to extinguish the blaze.

  A.J.'s head was bowed, as was Jackie's. Helen tore her gaze from the blazing wreckage that had been bringing Joe Buckley home just moments before. As if she might find understanding and solace, somehow, she traced the trajectory of Chinook back along the trail of smoke.

  What was . . .

  "A.J.? A.J., Jackie, look!"

  A white dot showed in the air. As they watched, the dot descended and grew.

  "Parachutes spotted," crackled from the speakers. "Visual confirmation that it is the ejection pod from Chinook."

  Helen and A.J. were already sprinting towards the likely landing area, somewhat to the right as carried by the wind. The emergency vehicles passed them, of course, and by the time they arrived the ejection pod had landed and Bruce and Joe were emerging from it.

  A.J. bulled his way through the EMTs. "Joe! Joe!"

  Joe grinned, painfully. "I tried to tell them it was a no-smoking flight, but nobody listens to me."

  Chapter 23

  Ken Hathaway's eyes widened a bit. "A radius of one hundred and forty-six met
ers—almost a thousand feet across?"

  "Or more," Dr. Gupta said, nodding. "Half again as far across if we assume a rotation of once per minute. And farther across, much farther across, if we also wish to generate Earth gravity instead of merely something close to Martian."

  The Air Force colonel scratched his head, looking doubtful. "A rotation of once every forty seconds or so still seems awfully slow. I'm sure we could spin up to considerably more than that and remain well within tensile safety limits. Look at what we can do with suspension bridges and all."

  Gupta let Jackie field that one. "If it was just a matter of engineering, Ken, we could build it to be any size you want it to be. We could put you in what amounts to a washing machine or one of those carnival rotor things. But the problem is that a lot of people run into disorientation problems when they hit rotation over about two or three RPMs. For flights with small handpicked crews, you can ignore that problem to some extent. But our crew is much larger and is being selected for a much wider range of functions. Some of the members will be only marginally space-worthy."

  "Tell me about it," Hathaway grunted, smiling rather crookedly. As an officer accustomed to the rigorous selection procedures of the military, he was still trying to get used to the much wider latitudes being applied to picking the Nike's crew. No one who suffered from really critical medical problems was being accepted, true. But Ken felt the definition of "critical" had been stretched to the breaking point. There was one member of the crew who was sixty-three years old, and another who was at least forty pounds overweight.

  Both of them, however, were also universally considered to be among the world's half-dozen top specialists at deciphering languages—and they were the only two who were willing to make the trip. So, aboard the Nike they would go, when the time came, whether the ship's captain was happy about it or not.

  Jackie continued her explanation. "Now, we're not taking anyone who's a complete groundhog—they're going to have to be able to take acceleration and no gravity and all that—but Dr. Wu is firmly of the opinion that if we don't use slower rotation for our artificial gravity we will have problems with a significant portion of the crew. On the bright side, he's also firmly of the opinion that one-third gravity will be sufficient to maintain bone mass and prevent the other problems associated with long-term null-g situations. Ten years ago, we wouldn't have been able to be sure, but he says the most recent experiments have been consistent and clear and he's comfortable with a one-third gravity setting."

  "Okay, okay. I agree, there's a lot to be said for a big ship. We should be able to make her pretty roomy, which God knows we're going to want. Still, even if I stop her from spinning, that's a hell of a lever arm I'm trying to turn with. Wouldn't want to break it off."

  Jackie laughed. "Don't worry. The supports are designed to take anything you'll be able to dish out, even with the engines we're giving you. Here, take a look at our first main design model of Nike."

  The 3-D imaging view lit up and, suspended in space, a model of Earth's first interplanetary ship materialized.

  "Thank God for modern design technology," Ken mused, staring at the image before him.

  "No kidding. Without state-of-the-art automatic modeling and simulation testing and expert design packages, plus actual years of in-orbit construction experience, we'd need years to reach a workable design."

  Ken knew the truth of that. Many people didn't realize how difficult it was to design a new machine of any type. In the days before computers offered Computer Aided Design/Computer Assisted Modeling packages, design was a matter of physical construction of prototypes, testing of configurations, and iterations of these processes that could take years.

  Even after the start of CAD/CAM in the late part of the twentieth century, the designs still had to be built multiple times and tested physically for a number of purposes. The computers back then simply weren't capable of modeling the full range of complex interactions the real world would throw at a device in a high-stress environment. That applied twice-over to spacecraft, which would have no safe harbor, no "side of the road" to pull over to, and which would be entering and exiting Earth's atmosphere under the greatest "environmental stress" imaginable. There was insufficient experience in the design of multiple types of space-suitable devices, in the assembly of spaceworthy habitats and vehicles, and related problems to permit the designers to make any useful assumptions.

  In the past two decades, however, things had changed. Just as an old-style CAD/CAM package had permitted one person to equal the design production of a dozen or more old-style designers, modern CDM (Computer Design and Modeling) packages made one person trained in their use equal to a department of old CAD/CAM users, plus an entire testing lab. The modern CDM packages integrated modeling software equally advanced from its predecessors like MATLAB—capable of modeling and testing a designed part to a degree never before possible. Components were automatically checked for their capability to endure the stresses inherent in the design intent, while the designer continued the main design work based on broad conceptual designs. The specifics could be modified at will, and the entire design reworked to fit new specifications, all in a small fraction of the time earlier generations would have needed. With the firm empirical knowledge derived from thirty years of the International Space Station and its successors in orbit, such CDM packages now routinely produced new satellite designs, new living modules, and so on for space use in mere days—designs that worked.

  Ken's hand reached out, tracing the ghostly outline of Nike. The main ship's body was one and a half times as long as her fully-opened span—about fourteen hundred feet. From slightly forward of the halfway point, a great wheellike ring encircled the ship, glittering with hints of both metal and transparent windows.

  "That's the habitat area, of course," Ken said, pointing. "Do you realize how huge this thing is? I mean, good God, it must be nearly three thousand feet around!"

  "We certainly do. And we'll all be discussing the logistics with everyone later. It can be done, though, with the priority that the government's put on it. The size is pretty much necessary, to give us room to operate in as well as to give us the gravity we need. We may be living in Nike for a year or more."

  Jackie circled one area of the hab ring and a separate view zoomed up. As it did so, the ring seemed to fragment into multiple identical segments with the profile of a sort of squarish croissant pastry that was being slightly bent in the middle.

  "The main structural elements here, and in the main body, are standardized units that lock together. The internals can be customized almost limitlessly around a set of standardized modular connection points. You'll have hallway sections that basically have nothing but empty space, and habitable sections that are in the center of a bunch of supplies like water which help with shielding. The same, as a rule, with labs, dining or rec areas—and all of them based on the same support and maintenance structure. The main body has its own standardized assembly parts. This allows us to crank out a lot of the ship from a relatively few assembly designs, then fill it up with what we need. The fuel areas, of course, are basically subdivided tanks."

  Ken nodded, continuing his visual tour. To the rear of Nike, six great blocky assemblies, arranged in a pentagonal rosette with the sixth in the center, ended in the unmistakable vents of nuclear rockets. Front and back ended in smooth curves, the forward end coming to a graceful point. Colored areas indicated windows and sensor mountings.

  "You've streamlined things along the front to back contours," Ken remarked absently. "Why? She's not going into atmosphere."

  "Are you objecting to her appearance, Major?" Gupta's voice was slightly nettled. "Can an engineer not also have some appreciation of aesthetics?"

  "Oh, no, no, not at all. She's beautiful. It's just . . ."

  Gupta accepted Ken's backpedaling with a gracious nod. "Still, it cannot be argued that there is effort involved in such design and manufacture. Perhaps making the ship less streamlined would be ch
eaper and more swift. Yet, there are other considerations."