Titan

by Stephen Baxter

  Her voice, over his VHF loop, was thin, persistent, scratchy.

  A hero. In tact, that had already occurred to him.

  He wasn’t about to tell Benacerraf this, but he hadn’t in fact dismissed the Titan proposal out of hand, when it first came across his desk. On reflection, he’d calculated, it was possible that a lot of constituencies could be brought to unite behind this bizarre proposal: for instance there would be plenty of work, at least in the short term, for the NASA centers, which were engaged in their usual turf wars over the latest set of cutbacks. This last project could help in the management of the final decline and shutdown much of NASA faced.

  The USAF would be more problematic. But even they—or most of their internal warring factions anyhow—could be brought into line, Hadamard thought, if it was pointed out that this exercise would at least destroy the Shuttle fleet, just as surely as using the orbiters for destructive tests or advanced weapons target practice.

  And meanwhile, inside the White House, there was—he had perceived—some pressure to keep NASA flying. Unusually, this Administration was trying to think ahead, beyond its own expected political death in 2008. They feared for the future of the country if—when—Xavier Maclachlan came to power, a future in which it seemed America was likely to lapse into fundamentalism, and isolationism, and a kind of high-tech Middle Ages.

  A huge technological program already underway when Maclachlan took office—an immense deep space mission lasting years, perhaps even spanning beyond Maclachlan’s term—might be a way to keep the spark of rationalism alive. Surely even Maclachlan wouldn’t be able to justify’ closing down the new launcher program if it meant stranding astronauts among the moons of Saturn.

  And, Hadamard reflected, he himself could indeed become some kind of popular hero. When this was over—even if the mission failed in space, even if it failed to get off the ground altogether—he could present himself as more than a costcutter, a man who could combine the fiscal targets of his employers, even the final run-down of NASA, with a genuine sense of vision.

  He could move from NASA, afterward, to his pick of jobs.

  Benacerraf’s proposal, all this crap about the higher ground, was just a ridiculous power fantasy to him, one in a long line of such dreams to emanate from the centers of NASA. But maybe he ought to back it, even so; maybe it could even be made to serve his own personal objectives.

  And maybe it would even work. Maybe it would turn a few young heads back towards engineering, instead of aromatherapy or goddamn homeopathy.

  And by the time it all failed, as it surely must, he would be long gone.

  A part of his mind wondered if Benacerraf knew what he was thinking, if she wasn’t as naive as she seemed. Maybe she was manipulating him on some level he didn’t recognize. If so it didn’t matter; all that counted, when it came to his decision, was the coincidence of this proposal with his own interests.

  And, he sensed, the decision was shaping inside him, as the various factors slotted into place in his subconscious.

  Perhaps Benacerraf would never know how. But, he suspected, she had won her argument today.

  He, Jake Hadamard, was going to send astronauts to Saturn.

  Good God. He’d come a long way since he took this job.

  A soft chime sounded in his ears, reminding him that he was holding up the VR immersion. For a moment he forgot his lines; then the prompter scrolled across the bottom of his visor. “Uh, I’m at the foot of the ladder now. The LM footpads are only depressed in the surface about one or two inches. Although the surface appears to be very fine, fine grained, when you get close to it, it’s almost like a powder. Down there it’s very fine…”

  Eagle looked like a gaunt spider, looming above him in the glaring sunlight, a filmy construct of gold leaf and aluminum, standing on this broad, level plain. He found it hard to concentrate, with Benacerraf standing there, tilted slightly forward under the weight of her backpack, watching him. A grandmother on the Moon was definitely not a part of Armstrong’s original experience, he thought.

  He got hold of the ladder with a gloved hand, and turned to his left and leaned outward. “I’m going to step off the LM now.” Carefully, he raised his left boot over the lip of the footpad, and lowered his blue overshoe to the dust. He felt his heartbeat rise, and he felt foolish, knowing he was being monitored by invisible techs just a few feet away.

  He felt as if he had stepped onto snow; the surface seemed to crunch as it took his weight. But then, a fraction of an inch in, he reached firm footing.

  There he was, one foot on this angular machine from Earth, the other on the Moon itself.

  It was time for the line.

  “That’s one small step for a man…”

  Christ, he thought. He had a lump in his throat.

  If only it hadn’t been Armstrong, he thought. If only it had been someone less thoughtful, a bullshitter like Pete Conrad, who would have cracked a joke and whooped as he somersaulted down the ladder of the LM. Then we could all have dismissed the whole thing for what it was, a stunt, and got on with the rest of our lives.

  Damn Neil Armstrong.

  The lunar surface dissolved. The blocky walls of the immersive VR tank—the centerpiece of the visitors’ center here at Kennedy—coalesced around him, breaking through the dark lunar sky. The harness suspending him relaxed, and his full weight descended on his shoulders once more, heavy and eternal. That feeling of buoyant lightness dissipated, and he was trapped on Earth.

  So, he thought, it had all been a dream.

  He felt a deep, sharp stab of regret, of loss.

  Benacerraf called them all to a meeting at JPL. Rosenberg wanted to review landing sites. In the end, such were their commitments to the accelerating refurbishment and training programs, only Mott and Benacerraf could make it.

  To Benacerraf, Rosenberg seemed more isolated than ever from his JPL. She’d expected some kind of excitement here at the heart of planetary exploration, now that Hadamard had announced the Titan program formally. But as they made their way through JPL’s corridors, lined with pictures of Mars, hardly anyone acknowledged Rosenberg—though some of the natives, aging hairies, stared curiously at Benacerraf herself, the most media-friendly survivor of Columbia.

  No wonder Rosenberg wants to leave so badly, Benacerraf thought. There is nothing here for him, even at JPL, his spiritual home.

  Rosenberg had booked them a meeting room, a plain box with a big wooden table, over which he’d spread out a gigantic softscreen. A multicolored map filled the softscreen. It was a Mercator projection, of the surface of a world, pock-marked by craters.

  It might have been a map of the Moon—or Mercury, or the southern hemisphere or Mars, or any of the small bodies of the Solar System. But this was Titan. Much of the map was coarsegrained, and it featured long white strips where no terrain was shown at all, particularly towards the poles.

  Rosenberg said, “This map was assembled from radar images returned by Cassini. Cassini is using Titan’s gravity well to provide assists to climb on to other targets, but on each approach the radar sends back a noodle—a strip of the map, as it surveys a swathe of surface—and each time Cassini is occulted we study its radio signals, squeezing out a little more data about the nature and structure of the atmosphere…”

  Mott said, “Why the radar? Why can’t we see the ground?”

  “Because of the smog,” Rosenberg said. “Titan has virtually no magnetic field of its own—unlike Earth—so the solar wind and the magnetospheric plasma from Saturn can get at the upper atmosphere directly. Beams of electrons, plus ultraviolet light from the sun, fall on the upper air of Titan, and drive a lot of chemistry.

  “The uv destroys upper-atmosphere methane, which then combines with nitrogen to form complex molecules like ethane, benzene, hydrogen cyanide, other nitriles. The hydrogen cyanide combines in big multimolecular groups to form adenine, a constituent of nucleic acids. The uv manufactures the simplest hydrocarbons, electrons, the r
est…

  “The hydrocarbons cluster in complex organic solids called tholins. The tholins make up the smog in the upper atmosphere, and they rain steadily down onto the land. And they’ve been doing it for four billion years… Now; Titan’s deep cold has a number of subtle effects. To begin with, once molecules are synthesized down there, they are going to stick around: the higher the temperature, the faster molecules tall to pieces. On Titan, even the oldest molecules might still be there, in the deepest slush layers. Like deep-frozen primeval soup.”

  The map was color-coded for relief; one whole hemisphere was, Benacerraf saw, significantly brighter than the other. “Here’s the dominant surface feature on Titan,” Rosenberg said. “It’s a plateau, the size of Australia, sprawled across one whole hemisphere. Two and a half thousand miles across. A continent of ice. The mapmakers at the U.S. Geological Survey called it Cronos.” He looked at them for response and got none. “Mythology. The leader of the Titans. Now, Titan is tidally locked to Saturn; as it completes its sixteen-day orbit of Saturn, just like the Moon around the Earth, it keeps the same face turned to its parent all the time. And this Australia-sized lump, Cronos, is on the leading edge, as Titan pushes around its orbit.”

  Benacerraf studied the map more closely. The whole surface of the moon was covered with craters, up to a couple of hundred miles across. Some of the crater floors were filled in with a pale blue color, up to a certain contour. And some had central peaks, which protruded from the washes of blue. The continent, Cronos, had less filled-in craters than the other, trailing hemisphere.

  Rosenberg said, “The cratering is a record of Titan’s history. Cronos appears to have an older surface, with a peak crater size of about ten miles—maybe a thousand of those—but also a handful of craters up to two hundred miles wide—big, old, eroded walled plains, their ice walls subsiding back into the landscape. The mapmakers call them palimpsests. Shadow craters. On the lowlands the cratering density is much less, and there is a peak size of crater of around forty miles diameter. That’s consistent with a young surface-renewed by ammonia-water vulcanism—with the larger, older craters, and the smaller ones, pretty much wiped out by the geology…”

  The meaning of the craters’ blue coloration was obvious.

  Benacerraf pointed. “Filled-in craters. Right?”

  “Right. Titan is what you’d get if you flooded the Moon with paraffin: circular seas and lakes filled with liquid hydrocarbons.

  “The nature of this hidden surface was the biggest mystery before Cassini got there. You see, the air should be depleted of methane in ten million years, by the photochemical processes that destroy it in the upper atmosphere. Titan’s a lot older than that, and it has methane. So the methane must be replenished.”

  Mott asked, “Are the oceans made of methane?”

  “No. It’s too hot. But there should be a lot of liquid ethane down there. The oceans are liquid hydrocarbon—seas of paraffin—with methane dissolved in them. That is the source of the methane. But there’s still a problem.

  “The orbit of Titan isn’t a perfect circle. It’s elliptical. So, even though Titan rotates to keep the same face to Saturn, any surface liquid is going to slosh back and forth: tides. Which means a dissipation of energy by tidal friction, which means the circularization of the orbit. Like the Moon around the Earth. So you need an ocean to get the methane; but with a big ocean, you should have a circular orbit. It was a paradox. Oceans, or no oceans? Because of that mystery the planners didn’t know what they were sending Huygens into. They designed that little probe to float, or sink in a less dense ocean, or to land in slush…”

  “But now we know the answer,” Benacerraf prompted.

  “Now we know the answer.” Rosenberg twisted to look at his map. “Those crater seas are big enough to serve as methane reservoirs, with maybe twenty percent of the fluid bulk provided by the methane. But in bodies of fluid that size the tidal friction should be negligible.

  “Besides, it now looks as it Titan may have a partially liquid interior. That ought to dissipate the orbital energy even more quickly than the surface reservoirs, so the whole question of the tidal constraint is still open. Anyhow, so there you have the solution to the puzzle. The answer was obvious ail along; we just weren’t thinking Titan…”

  As she stared at the map, Mott tried to smile. “And this smoggy bombsite,” she said, “will be home.”

  Benacerraf touched her shoulder. “Hell, if you’ve lived in Houston long enough, a little smog is nothing.”

  Mott said, “What’s it going to be like for us down there, Rosenberg?”

  “Different,” Rosenberg said bluntly. “Titan is an ice moon, like Pluto, Triton, Ganymede. The difference is, it’s overlaid by that fat atmosphere. At the core is a ball of silicate, overlaid by a shell of ice, six hundred miles thick. And on the surface, over a water-ice crust, lies that slush of complex organic compounds.

  “You have to understand that Titan is not like Earth. Its ‘bedrock’ is water ice, with a little silicate. We may see plate tectonics, for instance, and even volcanoes. But if so they are driven by ammonia-water vulcanism, deep in the icy mantle. We call it cryovulcanism. We’re going to see a lot of unfamiliar processes… And the weather is shit,” he said. “Cold. And overcast. Smoggy, as you can see.”

  “How cold?”

  “Co—o—old. At the surface, we’ll find a temperature of about ninety-four K—nearly two hundred degrees below the freezing point of water. And that’s with a boost from a greenhouse effect; it could actually be worse. But the deep cold is the reason such a small world has been able to cling onto its air. And, under the smog, it’s dark. We should pack flashlights, Paula.”

  Mott said, “Can we see Saturn?”

  “From the surface? No. Sorry.”

  “Jesus.”

  “So, landing sites,” said Benacerraf. “We have to choose an equatorial landing site, because that’s all we can reach.”

  Rosenberg said, “Correct. But wherever we land it’s going to look superficially the same. The atmosphere is so thick that the temperature scarcely varies, from pole to pole. What we need to find—for the science, and so we can supply our own needs—is an interface between geologic units. An area where several different types of terrain come together.”

  “You have a suggestion?”

  “Yeah.” He stabbed a finger at the map, near the center, close to the “coastline” of the continent, Cronos. “There’s a mountain range here, sprawling right across the equator. And a few degrees to the south of the equator, just here, is the highest mountain on Titan. The Survey called it Mount Othrys.”

  Mott asked, “More mythology?”

  “Yeah…”

  Benacerraf said, “Why do we need to be near a mountain?”

  “I told you everything is covered” in slush, in tholins. We’re going to need water ice, however. But there is rain. Ethane and methane rain,” he said. “The rain evaporates before it reaches ground level. But it should wash the tholins off the elevated ground. So the peak of Othrys will be exposed bedrock.”

  “Bedrock,” Mott said, not following.

  “Think Titan,” Rosenberg said.

  “Oh. I get it. Exposed water ice.”

  “All right,” Benacerraf said. “So we come down somewhere near this mountain.” Just to the north of the mountain, she saw, there was a large crater, maybe twenty miles wide, filled with a cashew-nut shaped lake. “How about here?”

  Mott studied the map. “The crater has no name.”

  Rosenberg shrugged. “The USGS didn’t name anything much below a hundred miles across…”

  “Then we’ll have to,” Benacerraf said decisively. “Niki, you got any suggestions? This is going to be home, after all.”

  Mott smiled. “A dingy stretch of fluid, overlaid by twenty-four-hour smog, and stinking of petrochemicals? Paula, as you say, it’s just like Houston. We’ll call it Clear Lake.”

  “Clear Lake it is.”

 
They fell silent, then, and looked at each other, here in the muggy Californian warmth, the bright light of the meeting room.

  Clear Lake.

  Benacerraf thought, What the hell are we doing?

  She tried to imagine how it would be down there, on the surface of Titan. In the pitch dark, laboring through freezing, sticky slush. Completely alone, without resource, save for the companions she took with her and whatever they could land.

  Possibly, probably, for the rest of her life.

  It would be a cold version of hell.

  But her heart was beating, fast, and she smiled.

  Jackie’s right, she thought. She was being selfish. Who could turn down an adventure like this?

  The moment broke. The three of them pored over the map, picking out more features, assigning tentative names, on the world that awaited them.

  Gareth Deeke, Air Force officer, drove steadily north on Colorado Highway 115. He drove with the windows down and his sun-roof open, despite the crisp chill of the autumn air. The sun, high and small, beat down on his scalp from the immense blue sky; but his eyes were shielded by his mirrored glasses, and visibility was good—in fact he could see for miles, as if the air was glass.

  Deeke loved the mountains: the emptiness, the huge sweep of the landscape, the sense of scale and frozen geological drama opening out all around him. He relished the feeling that he was embedded like a fly in amber, in this flashbulb moment of time.

  He reached the right turn for Cheyenne Mountain with regret.

  He could see the car park. It was the tabletop of a plateau, which jutted out massively from the side of the mountain. The steel bodies of cars glittered on its surface, in their neat rows, like ranks of insects.

  The plateau was artificial. It had been constructed by piling up the granite which Air Force engineers had scooped out of the heart of the mountain.