Encounter With Tiber

by Buzz Aldrin

  It was also a place to use the plastic bags to eliminate in zero g; I was amused to realize that this was the first time I had been on a ship with someone else, in space, used the bathroom, and not had an audience. It did seem more pleasant, on the whole, although some design genius had made the bags transparent, so a moment later we all emerged simultaneously into the corridor with whatever we had done more or less on display. Carefully ignoring that, we all tossed our bags into the recycler.

  The scientists went back to their compartments, the doors closed, and that would be the last we saw of them till the captain announced an all-clear. The compartments, at the moment, were oriented so that nominal “down” was toward the booster; thus the bunks could serve as acceleration couches.

  I got into my seat at the pilot’s station and said, “Ready, sir.” The clock showed we had six minutes to go.

  Gander nodded. “Well, then, here we go. Olga’s back on station, and she says everything looks perfect. You’ve got time to recheck the board once more.”

  I did, again, and for the hundredth time that day everything looked perfect. I rested my hands on the controls and made myself relax; this was largely a job for the computer, just like the others, but if there were any need for me to override it would come up very suddenly.

  The booster behind us would need to fire for about eleven minutes, accelerating us at just over one g, to get us onto the correct trajectory. One g is what the gravity is on Earth, of course; the purpose of putting the scientists onto their bunks was not to protect them from forces that their bodies were used to anyway, but to make sure that they could not suddenly fall when the acceleration came on, and to keep them from getting hit by anything that might shift and come loose. The captain and I in the control cabin, and Olga back near the ship’s machine and farm sections, were presumed to be able to look out for ourselves.

  We counted down and watched the computer screens; this needed precision in tenths of a second, faster than we could reliably handle controls, and our only function was to make sure that if something got far out of bounds we shut down before anything worse happened. I had primary responsibility for watching the trajectory, to make sure we stayed on it; Olga was watching the booster for any signs of components failing due to heat, stress, or vibration; and Gander was watching us.

  Gander counted down dispassionately. We hit zero, and there was a deep, low-pitched thunder in the ship. I sank into my chair; there was an odd feeling of suddenly being back on Earth, because the gravity was the same.

  Once again, things were perfectly normal; the trajectory stayed completely within bounds, and Olga later said nothing got anywhere near the critical range. The time crept by and the biggest problem I had to face was staying absolutely alert and keyed up even though nothing required me to do anything. At last, right on schedule, the engine shut down.

  I took a quick look at the camera. The Earth already looked different; we had increased our distance from the surface severalfold, and now we were moving away from it at about twelve kilometers per second. We would cross the Moon’s orbit in less than nine—far faster than the ballistic trajectories to the Moon that still took about three days, just as they had in 1969—but we would still take around seven months to get to Mars.

  “Olga, Jason,” Captain Gander said, “here’s what I’ve got in mind: I’d like to get the whole job of orienting and spinning up done, and then let everyone take a long rest. That’s probably another three hours of work, and everyone has already put in a nine-hour day. How do you feel about it?”

  “I’m not badly tired yet,” I said. “And the idea of getting everything into good shape so that I can really enjoy the rest afterwards seems pretty appealing.”

  “I feel the same,” Olga added.

  “All right, then, it’s unanimous among the ruling class.” Gander grinned. “And the reason I brought it up was that the scientists had already suggested it.”

  The first part of the next three hours, turning over the personal compartments, was all the hard work. Objects have no weight in zero gravity, but they still have mass, which means they still have inertia. You can easily push a ton off the floor but once it’s moving it will really hurt to stop it. Furthermore, in zero gravity your footing isn’t quite as secure as you might like; friction depends on the force with which the two surfaces are held together, and without gravity to create those forces automatically, you always have to think of bracing yourself.

  There were several people there with experience doing physical labor in zero gravity, but I wasn’t one of them. I had worked with the others twice in training, and that was all. Olga and Nari seemed impossibly graceful and efficient, finishing their allotted tasks in short order and promptly taking over and doing everyone else’s. What we were doing was rotating the personal compartments 180 degrees, to the direction they would need to face from now on, with “down” being toward the heat shield. Since each of them was really not much more than a very fat, tall man’s casket, and there was little that was intrinsically heavy about them, it was mostly just the sheer awkwardness that slowed us down and turned the job into real work. We had to remove the end compartments from the two racks (putting them into the common area and the lab space temporarily); flip the ones still in the racks over into the adjoining racks; rearrange so that the ends of the racks were free; then finally flip the end compartments as we put them back in. Miraculously, when we checked at the end of the process, all our little coffins were facing in the right direction, but all of us were sweating, and I know that I and a few others had some bruises.

  Deploying for sustained flight was a much simpler business, because the machines did all the work. First we separated the booster stage from ourselves on a set of three-kilometer-long cables. (The fruit of the few things we had learned so far of Tiberian science: by studying some of their fabrics and fibers, we had learned how to make lighter, stronger, and more compact ropes and cables, including noncryonic superconducting cables, than anyone had known were possible.) Our power plant, which would provide our electricity through most of the voyage, was inside a fairing at the top of the booster, and that added to the mass.

  Using the small jets, we gradually worked up speed until we and the booster were swinging at opposite ends of the cable, whirling around each other like two skaters holding hands, with the MarsHab moving at around 25 meters per second, so that we went around about once every eight and a half minutes. With MarsHab, landing rocket, and heat shield, we had about twice the mass of the mostly-empty booster plus power plant, so the center of mass of the whole system was on the cable about a kilometer from us. Whirling around our joint center of mass, at our rotational speed, we were producing about a third of a g of centripetal force, about the surface gravity we would experience on Mars.

  We had spun up so that the cable rotated in a plane that faced the sun; now we signaled the booster, and it jettisoned the fairing around the power plant. As we watched through our cameras, arms extended automatically to stretch a thin reflective film into a large parabolic reflector.

  The parabolic reflector had sat folded up inside the top of the booster. It was made of sheeting thinner than paper and long, very rigid supports made of the same Tiberian vacugel that was used for Clipper hydrogen tanks. Once deployed, the parabolic mirror that it formed, facing the Sun, was fifty meters across, a gossamer structure of the kind that can only exist in space. On another set of arms, the second parabola, inside the first and facing it, extended into place; this one was little more than a meter across.

  Parabolic reflectors are useful because they will bring a beam of parallel light into a single point at their focus, and conversely if a light is placed at their focus, they will shape the light into a parallel beam. A television satellite dish is a parabolic reflector, because if an object is distant enough, the light rays coming from it will be so close to parallel that it makes no difference. The television signal comes in as radio waves from a satellite hundreds of kilometers away; these are ne
arly parallel, so the dish focuses them to that relatively small spot in the center where the receiver is mounted.

  The same principle allowed us to have a highly efficient solar dynamic power plant. The two parabolic reflectors had been placed so their foci were identical. Parallel sunlight hit the first reflector and bounced into the focus; from the focus it hit the second reflector, and as it was reflected, was reshaped into another parallel beam. But where the large reflector had an area of 1963 square meters, the beam was now just a meter wide—and 2500 times as intense. Sunlight in space at the distance of the Earth’s orbit carries about 1300 watts per square meter; this meant that a bit over two and a half million watts was in that narrow beam.

  The beam in turn was focused by a Fresnel lens into a boiler; in the boiler was liquid neon. The neon boiled, expanded into white-hot gas, passed through a series of turbines, and then was expanded through a system of radiator pipes that ran down the body of the booster on the side that now would stay turned away from the Sun. By the time the neon reached the end of the pipes, it had cooled considerably; it was then compressed, releasing more heat through a second radiator, until it reliquified at cryonic temperatures.

  The efficiency of a heat engine—like a turbine or internal combustion engine—depends among other things on how big a temperature difference it operates across and how much energy is lost in various turbulent processes in the working fluid—“sticky” or viscous fluids tend to absorb a lot of energy into themselves, “thin” fluids do not. We were moving heat from a two megawatt beam to the near absolute zero of space, and using one of the thinnest fluids known. Not surprisingly, we were capturing almost half of the incoming energy, something over a megawatt, which meant that the power now flowing over the cables was enough to reseparate the water the fuel cells had produced into hydrogen and oxygen, so that we were back at full charge, and to operate all the ship’s equipment with plenty to spare.

  That meant a lot of other things, too. With some gravity (at least enough to get water to a drain) and plenty of power, the ship’s shower and clothes washer were available, and the “farm,” the other technology we had copied from the Tiberians, could begin to turn out fresh vegetables.

  The captain and I volunteered for the first watch; everyone else went swiftly off to sleep. Curiously, after all the hubbub of the day, in just a few minutes the ship was quiet except for the distant hum of the machinery. The stars wheeled by the windows, twice as fast as the second hand on a clock, but it gave no sense of motion since I could “feel” absolutely that the direction of my feet was down. Now we weren’t confined to food that behaved itself in zero gravity, so I made coffee. For a long time we sat in the cockpit, occasionally looking at the camera images as the Earth and the Moon steadily shrank behind us. In a bare few days they would look like two bright stars, ever so slowly crawling toward each other.

  But it wasn’t being on an interplanetary flight that seemed strange, somehow. It was that still-large blue Earth—it seemed like an intruder into the self-contained world of the MarsHab. Already I was sensing that this new life was going to feel profoundly normal for a long time.

  We were each having our second cup of coffee when Captain Gander leaned back a little and said, “Well, now that you’re here, and no one else is, I suppose it’s as good a time as any to discuss some things.”

  4

  I WAITED A LONG breath, and then said, “I’m listening, sir.”

  Gander glanced sideways at me. “Oh, don’t sweat it, Jason, I’m not going to chew you out or tell you to watch your ass. Just a couple of things you need to have in the back of your brain.” He stretched and yawned. “My God, twenty-five years of space missions catches up with you. Well, first off—” his voice lowered to a murmur “—I presume Lori briefed you, at least somewhat, on our political situation here. You notice that not only are you and I the only Americans on board, but we’re also the nonscientists in the team.”

  I nodded. “I had thought of that, but people seemed to be making a big deal out of who should be the officers.”

  “That’s what we wanted,” he said. “You’ll also note only one of the scientists is Russian—and he’s so much the expert in the field that nobody could have left him home.”

  I nodded again and said, “This adds up to something, but I’m afraid I don’t understand what.”

  Gander smiled. “Well, if you don’t, then perhaps some quiet misdirection we’ve been doing is having a positive effect. Our diplomats tried to look very worried about the possibility of a foreign crew, and the Russians played along with us, so that it looked like we only grudgingly let Olga have the engineer’s job. But the truth is just what you’d think; what really matters, what has really mattered all along, is who’s going to get access to the Encyclopedia. And we do have to worry that the team that’s going to dig it up and read it doesn’t include an American. They may or may not give us full access to all their work, no matter what the treaty says. That applies especially to the Chinese, of course. Things aren’t as bad as they were in the Cold Peace, not by a long shot, but you still can’t really say we can trust them. And NASDA and ESA may well have agendas of their own, too.”

  “So what do we do?” I asked.

  Gander smiled broadly now. “We have a little extra surprise waiting for them. Do you remember how long they’re planning to take to dig down to the Encyclopedia?”

  “A couple of months or so, isn’t it? First they want to find out about any surprises in dealing with Martian ice, so they’re going to start out by excavating at least partway to the settlement. So that means they’re going to cut out the ice in numbered blocks so they can study the position of the microdebris. The kind of thing that Ilsa calls ‘toothbrush and tweezers archeology.’”

  “Exactly. And before that time is up, a second team of scientists will arrive—top people as good as the team we’re taking, which is really saying something—four Americans and four Russians.”

  I started. “How are they getting to Mars? I thought this was the manned launch for this opposition.”

  “We’re hoping that’s what everyone else thought. They’re coming out on Aldrin.”

  I gaped at him for a moment; then I almost laughed out loud. “Of course. We could have started doing that any time.”

  Gander nodded. “It’s a new concept they’ve gone to, after years of talking about it. Now that living space is finally exceeding personnel at Mars, they want to use cyclers to take people out as well as to bring them back. So Collins will keep on doing what it always has, flying with a crew from Mars to Earth, dropping its crew off, and getting a gravity assist at Earth that sends it back to Mars for another cycle. But from now on we’ll call it the REcycler—Return to Earth cycler. Aldrin was held over for several months at Mars, waiting for a trajectory that would allow it to return to Earth to be captured, rather than gravity assisted. From now on it’s the GOcycler—the Going Out cycler—and what it will do is depart Earth with a crew, deposit the crew at Mars, be refueled here, and then return empty to Earth to pick up another crew.

  “The tricky part for NASA and the Russians was hiding it from our Chinese, Japanese, and Euro friends. To make it less obvious we had to have Aldrin go back at the last possible minute, just as if it were a badly delayed crew return. Then we’ll announce that Aldrin needs an emergency repair—which is consistent with that delayed return—and divert her into an aerobrake to place her in a highly elliptical orbit around the Earth. A supposed ‘technical crew’ of five Americans and five Russians, in two Pigeons, will go out to rendezvous with her and to supervise putting new fuel tanks on her. It’ll all look perfectly normal—till instead of coming back, the Russian/American crew light Aldrin’s engine and ride her on out to Mars. They’ll get there about five weeks after we do—which is to say, the dig team here won’t be more than a few layers of ice down. So we’re not getting shut out of anything, and neither are the Russians.”

  “Slick,” I said.

  �
��Well, we can’t count on the Chinese, the Japanese, or ESA taking it as good sports. If any of them were planning to share fully with us, they might very well take it as an insult; and if they weren’t, they aren’t going to be happy when they can’t snooker us. Not to mention that if they were up to anything dishonest, their people on this ship would have to be in on it, you know. So we might have a bad situation, one way or another, on our hands, and at the least we’ll probably have some wounded feelings. I just wanted to make sure you knew it was coming and weren’t taken by surprise. And, of course, at least until I tell you otherwise, you can rely on Olga and Vassily. She’ll be briefing him within the next day or so. Any questions?”

  “I don’t think so.” I couldn’t help smiling. “I know it will cause some trouble here, but it’s nice to see that we can still manage not to get taken for a ride.”

  “That’s the spirit.” He looked down at his screen and said, “As usual, right when we start out, we’re going to have to do some course corrections. It’s not easy to get a spinning object onto a precise orbit.” His fingers flew over the keys, setting up a series of bursts from the ship and the booster to get us closer to where we belonged; I watched over his shoulder, fascinated at how fast he could do that. “That’s a starter,” he said.

  I was about to ask if I should set it up to execute when he transferred it to a genetic algorithm, defined a few parameters, and set it to optimize.

  He looked up at me and grinned. “Too many people take too much pride in their work. A human being might accidentally come up with something as good as a genetic optimizer, but not likely. I can stand the thought that a machine can do this better than me.”

  “Same way I feel about flying the ship, captain.” I stood back and waited for the output. A genetic optimizer is a fast, efficient way to do something that couldn’t have been done at all a century ago. Suppose you have a problem where it’s easier to tell which solution is better than it is to solve for the best solution. Then one way to solve it, if you have enough time, is to generate a hundred random solutions and keep the best ten in that group; make nine copies of each of those ten, randomly varying them, so that you bring the total back up to a hundred; and repeat the process. Stop when you have a good enough answer or when the answers stop improving. It’s evolution in action: each successful solution gives birth to another generation, some of whom are “mutants.” Successful mutants replace their parent-stock; sooner or later you get something successful enough.