by Buzz Aldrin
By the next day, all the scientists were happily corresponding. Never having been much of a writer, I didn’t pay much attention.
It was two days later at dinner that Dong and Tsen announced, without any fuss, that they had indeed had orders from the PRC government to make sure that if there was a chance to secure exclusive access to part of the Encyclopedia, China got the benefits. “It was always supposed to be the top priority to get the information, even if that meant we had to share it all,” Tsen explained. “But it seemed to us that now …” She looked sideways at Dong.
He grimaced. “We didn’t like those orders much. Nobody does in the sciences, you know. Almost all of us would like to publish everything, all the time. So … well, now we know we can’t keep any part secret, now we don’t have to try.”
Olga frowned. “Aren’t you risking—”
Dong smiled. “Well, that is one way to look at it. By telling you this we have committed a political crime. What do you think the odds are that the Chinese secret police will come and get us where we’re going? And we both know there will be decades of work for us at Crater Korolev.”
“So Mars has its first refugees?” Gander asked.
“New worlds always do, eventually,” Tsen said. “That’s one of the reasons why they are so important.”
5
SEVERAL WEEKS FOLLOWED THAT were pleasant with no really memorable events at all—which was fine with me. It’s only in the movies that an astronaut wants things to get exciting en route. The shipboard routine ran smoothly, and for the most part we settled gratefully into it.
With the tension revolving around the secret Aldrin mission resolved, the MarsHab became a very pleasant place; there were minor tiffs now and then, but just the fact that people could go to a personal compartment and close the door seemed to ease that tension. We got e-mail from the team at Korolev Base, the outbound Aldrin crew and the inbound Collins crew, teasing us about that “luxury,” and not long after that NASA announced that there would be an unmanned cargo shipment of personal compartments sent to Mars “at the earliest opportunity.”
Paul and Nari seemed to find that amusing; I asked them why. “Because we were on the early voyages where the MarsHabs were just one big commons, for every practical purpose. Floors for functional purposes and to increase the working area, but nothing else. You’d be amazed how many ways there are to want privacy; there was a standing joke about ‘astronaut’s dysentery’ because the only place you could be by yourself was the bathroom—sometimes I’d spend an hour in there just reading a book or something.” Nari shook his head sadly. “You know, for space missions, we people from the advanced countries aren’t really well-suited. We aren’t used to the idea of sleeping ten to a room, let alone doing almost everything out in public all the time. It’s just interesting that it took them so long to come up with these personal compartments.”
Paul added, “But it’s not surprising at all that once we got them everyone is demanding them. Those little people-boxes are luxury condos compared to what the current Martian stayover crew has.”
Olga had just been relieved, and she came in and sat down, close to me. I still hadn’t tried to turn it into anything romantic—maybe because I wasn’t sure she’d want to, maybe because of the thought in the back of my head that she was planning to stay on Mars, but I would be leaving a little before the next opposition, after refueling and reprovisioning Collins. Or, I suppose, maybe because if I got involved with her it was going to be serious, and there hadn’t been anything serious in my love life in at least a decade. I was out of practice.
We sat for a long moment, the four of us just enjoying a moment’s rest, till Paul said, “Nari, I’ve got another explanation. If it resurfaced at any time after the Tiberians died or abandoned their settlement, then all that happened was that the lander sank into the lake, fell sideways on the icy bottom, and then everything refroze over it.”
“And the graves?”
“The corpses sank further into the slush—”
“Than a magnesium-titanium hull with several large pieces of heavy equipment? And they all sank while remaining perfectly laid out—”
“They were frozen solid.”
“Not if—”
Olga glanced at me; I shrugged. She said, “Is this a private fight, or can anyone get into it?”
“It’s not really a fight,” Nari said. “I’m just trying to straighten out this crazed Frenchman by teaching him a little about Occam’s Razor. Here we have a Tiberian lander sitting right on the discontinuity that Dr. Fleurant so brilliantly found, right? Just below that discontinuity—only a couple of meters—we have a large number of dead frozen Tiberians, and if our ultrasound and X-ray reflection tell us anything, they tell us that they are all on their backs with their arms folded over their chests—the same position we find in the lunar cemetery. So what I say is the discontinuity formed at the time the lander fell over, after the Tiberians died. The ice is structured as you’d expect if a cold lake froze on that site, so I think they were caught quite suddenly in a flood, at their campsite, where twenty-two Tiberians had already died and been buried. Quite a few of them drowned in their beds in the huts. So, I say, there is only one such discontinuity found in water ice all over Mars, wherever there is permanent ice. And the Tiberians are sitting on it. I say they did something to cause that.”
Paul spread his hands out emphatically; his wrists flipped his hands upward. It was sort of an aggressive shrug. “Which is at least two huge leaps of logic, for a man who wants me to think about Occam’s Razor. Suppose that when they made their camp they were on the ice of Crater Korolev, and then they got stranded and died. A thousand years, or two thousand, go by, and then there’s a volcanic eruption that releases an enormous load of water onto the surface, perhaps near the equator. It might be a geyser, or maybe one of the extinct volcanoes had a huge Krakatoa-type explosion from groundwater steam. The water ends up everywhere for a while—it’s a good greenhouse gas, Mars warms up a bit, and all those water-carved features we see today get laid down. Then the water gradually freezes and sublimes in the low pressure, gets carried as water vapor to the arctic, and is deposited during northern winters. That could take, oh, four thousand years. During that time, the lake in Crater Korolev gets constant sunshine for a large part of the summer—after all, it’s at seventy-three degrees north—so the frost there melts and freezes over and over, forming the solid ice that so perplexes Nari. For all we know, had we known what to look for in 1200 A.D. and had the telescopes and spectroscopes to do it, the whole question would have been settled by watching the last of the water vaporize and freeze into place.”
Nari sighed. “How anyone with Paul’s talents got the habit of discarding so much evidence, I’ll never know. Paul, nowhere on Mars is there the kind of inversion you’d expect, caused by water freezing from the top down instead of the bottom up. That means the water went in suddenly, and was already very cold, probably just at the freezing point, when it was deposited, so that unlike normal liquid water it froze from the bottom up. Now what does that look like? Mars has a very thin atmosphere made up of a gas, carbon dioxide, whose behavior is very temperature sensitive. Things can happen very suddenly planetwide; air pressure changes drastically every spring and fall, even as it is, and for example water might go into the air, and later come back out, almost instantly. So here we have a wrecked ship and many dead Tiberians—mostly dead indoors, as if something happened suddenly, probably at night, or maybe while they were all ill. We have a sudden flood, on a planet which is undoubtedly very good at producing sudden floods. We have them at the bottom of the sudden flood. And in all the eons that Mars has been there, this only happened to happen during the few brief years the Tiberians were there. And you think that the Tiberians being there and the great flood happening are completely unrelated?”
Fleurant shrugged. “Suppose there is a ‘discontinuity-making event’ that happens only now and then. Suppose the most recent one is
the most extreme of them, so that it has erased all the older discontinuities. Perhaps it is something that causes an almost overnight thaw and freeze. Well, then the whole Tiberian camp was there—frozen and dead, two thousand or four thousand years after they all died from who knows what, whatever aliens die from. Then the whole camp sank—”
“Where all the corpses landed on their backs and all the buildings landed upright,” Nari interrupted. “At least your previous silly idea had the virtue of being superficially plausible. Whereas in your present idea, three mysterious things happened—all the Tiberians died, their whole camp got frozen into the ice, and the discontinuity formed—all at the same time. How very unlikely can you get? On the other hand, if you assume they were all caused by the same thing, presto, the problem is simple. All we have to do is find that thing.”
“But—”
By now they really weren’t talking to us anymore; they didn’t even look up when Olga and I got up. We went to one of the windows to sit and watch the stars wheel by, many times more than you could ever see on Earth. We’d been spending a lot of time just sitting together lately.
When we were about two weeks from Mars, it began to appear as an orange dot, distinctly round rather than a point; from then on it grew steadily. By that time the Sun had shrunk to a smaller, bright white disk, about a third of its apparent size from Earth.
By that time Olga and I had formed a habit of having at least one meal per day together, and now we generally used it as Mars-watching time. We were in the early part of northern spring—the vernal equinox had been April 9, 2034—so at least there would be sunlight, and the days would be growing longer, when we arrived at Korolev. The Martian year is about twice that of Earth, minus forty days or so, so each season there is around half an Earth year. We would have almost a full year of spring and summer before having to experience the worst of Martian arctic conditions.
We watched as dust storms swirled around the planet, and we saw the northern polar hood (the layer of clouds above the north pole) dissolving in the spring sunshine, as the southern polar hood began to form. “The reports from Korolev base say the air pressure is already falling a little,” Olga said. “And the temperature is getting up above the carbon dioxide freezing point most days now.”
“Knew I should’ve packed more summer clothing,” I said.
“Silly.” She looked down at the keypad, where she had been making some notes. “The thing is, Jason, I’m going to be living there for a long time. I will see some seasons, you know. And therefore, I’m trying to get myself to think of the rhythm of the Martian year. I want to be in the habit of looking forward to the next season, just the way people do on Earth. And since air pressure and temperature are the two real signs of spring in the Martian arctic, well, then, I’m going to learn to think about them the way we do about the first robin at home.”
I nodded. I was trying not to let it bother me that I would be around Olga for a bit over a year after our arrival and then would be getting back on Collins to return to Earth. I wasn’t really emotionally involved yet—I didn’t think—but then again …
Mars is a small planet, and though they take a long time, interplanetary journeys move fast. It was only during the last ten hours or so of our approach that Mars became larger in our windows than the Sun. Or so they told us. By that time Olga and I were far too busy to spend much time looking out the window.
None of the maneuvers involved in getting a MarsHab to the Martian surface is complicated in itself, and after all our job is mostly to make sure that there’s someone there to take over in the very unlikely event of a computer failure or some kind of severe software glitch. Every now and then there’s an opportunity to get a bit better than machine-optimized performance, though not often. Mostly my job was to watch the machines do the work.
Nonetheless it’s nerve-wracking. We were flying toward Mars at far above its escape velocity. If we had brought fuel from home to turn around and fire a retrorocket, we would have had to bring a fully fueled rocket as big as the empty booster that now hung at the other end of our tether—and of course we’d have needed a much bigger booster to throw us and the full booster here. Thus what we were going to do was aerocapture—get down from our high interplanetary velocity, to one slow enough to be captured into Martian orbit, by interacting with the Martian atmosphere.
“Interacting” is a pretty mild term for what it involves. Essentially you’re going to come in as an artificial meteor, aiming to go through the atmosphere at an angle that isn’t too shallow (so you won’t bounce off like a stone skipping on a pond, losing no velocity and thus continuing on into a long orbit around the Sun, as you slowly run out of food and air), or too steep (so that you don’t enter the lower atmosphere, where the air is thicker, at very high speed, and burn up or hit the ground). Between those extremes there are angles where a great deal of the energy of the ship can be converted to heat in the atmosphere. You emerge after going through the outer atmosphere with a great deal of your speed lost, enough so that you go into orbit instead of continuing on endlessly.
Fortunately the Martian atmosphere is fairly friendly to the process. To begin with, it’s thin. Earth’s surface pressure is about a thousand millibars; Mars’s is about six. Secondly, thanks to the low gravity (about a third of Earth’s) and high molecular weight of the atmosphere (44 versus Earth’s 14.4) Mars has a scale height of 10.8 kilometers, considerably more than Earth’s 7.9. Once you grind that through the logarithmic function, it works out like this: on Earth, there’s half as much air for every 5500 meters you go up. So at 5.5 kilometers up, about the height of Mount Popocatapetl, there’s half as much air; at 11.1 kilometers up, about as high as the old airliners used to fly, there’s one-fourth as much; and so forth. For Mars that number is not 5500 meters, but 7486—the Martian atmosphere, though very thin, thins out much more slowly than the Earth’s. To do an aerocapture you have to aim for air of a specific thickness and a large scale height guarantees thickness that doesn’t vary as much with altitude—and thin air farther away from the planet—so that you have a wider window you can hit, farther away from the rocks.
I wasn’t thinking about any of this consciously as we got ready. The first step was to jettison the booster, which had been swinging around with us for the months of the journey, on the end of its long cables, giving us artificial gravity.
“All right,” the captain said, “it looks good, Jason. Authorize the computer for jettison.”
“Yes, sir.” I entered the command; the computer began a countdown.
There was a slight clang, and suddenly we were in zero gravity for the first time since our Earth departure.
We had a few hours, now, for fiddling course corrections and adjustments and to send the robot outside to examine the heat shield that was now pointed toward Mars. Everything was fine and on target; it might almost have been yet one more drill.
As we drew closer and the hours crawled by, the rate at which Mars appeared to expand in our window became greater and greater. Finally, with Mars now swollen to twice the size of the full Moon seen from Earth, we strapped in and gave the final commands for the computer to take us through aerocapture.
The first pass is always the roughest because it’s when you’re spilling the most energy. We tore halfway around Mars in less than twelve minutes, pinned flat to our couches by several g of deceleration. I watched the instruments, but at such speeds and weighing several times my Earth-normal weight, if I had seen anything wrong I very much doubt I could have done anything. As the hab rose back into high orbit, and the glowing heat shield outside gave up its heat to space and cooled back down, we all sipped water, stretched, relaxed, and got ready for the next pass.
It took one more pass through the atmosphere to spill the energy and bring us into a low enough orbit; then we had to burn a little bit of our precious inboard fuel to get our orbit circularized, so that we passed over the Martian poles at an altitude of about 220 kilometers. “You need a break
yet, Jason?”
“I’d rather take one on the ground, sir, and so far I haven’t touched a control. Don’t tell the taxpayers, but there’s really no reason for me to be here.”
“Me either, you know. Except to remind our science team to eat and sleep. Well, then, how long is it until we next have a window for a descent to Korolev? Is there time for a bathroom break and to let them know our plans?”
“The computer put us into position to do it early,” I said. “We’re in a one-hour-forty-nine-minute orbit, and we’ve got a marginal window coming up in nineteen minutes, a good opportunity coming up in two hours and ten minutes, and a not-so-good one in four hours. After that we’d have to wait a while or try to steer a lot during reentry.”
“Well, we don’t want to try that. Okay, go for the good approach. I’ll call up Korolev and tell ’em to set out some extra plates.”
The descent was the one part I probably could have flown manually. I guess in the old days, the stick-and-rudder early astronauts would rather have done that. But in the intervening seventy years, computers and software had improved a lot, whereas I was basically the same design as Yuri Gagarin. And I sure wasn’t going to bet the lives of eight of Earth’s best brains on my piloting skills unless I had to. So just as with everything else in the mission thus far, I turned it over to the machine, and sat and watched, and hoped I wouldn’t have to move or act at all.
It wasn’t nearly as steep a descent as you make to Earth in a Pigeon, for several reasons: the smaller Martian gravity meant orbital velocity was much slower, the greater scale height meant we could start slowing down higher up, and the thinner atmosphere simply didn’t produce as much heat so we could spend longer in reentry without greatly increasing our risk. Consequently I would fire our retrorocket just as we were crossing the equator; we would pass almost directly over the north pole and finally descend to Korolev.