Titan

by Stephen Baxter

  The pressure mounted, climbing fast, impossibly quickly, slamming her into the couch. Titan’s thin, cold upper atmosphere was hauling at Jitterbug in earnest.

  … Assuming, of course, the theoretical models of Titan’s atmosphere were right. And Mott, after six years in microgravity, for all her exercising, wasn’t as robust as she used to be.

  A pale, gray-white glow began to gather at the base of the window. It was plasma, the atoms of Titan’s air smashed to pieces by the passage of this intruder from Earth, gathering in a thickening shock layer beneath the Command Module. The air of Earth produced a pinkish, almost welcoming glow on reentry. But the light of Titan’s plasma, a thin mix of ionized nitrogen, methane and argon, was a cold pearl-gray glow.

  Even the plasma was alien here.

  Benacerraf was still speaking to her, she realized belatedly. She tried to call back, to acknowledge; but Benacerraf’s voice was breaking up in static as the plasma shell engulfed Jitterbug.

  A hundred and eighty miles above the surface, the deceleration peaked. Mott lay on her back, buffeted, compressed, while the cabin equipment rattled around her. She was deep in the atmosphere, moving at Mach twenty. The weight on her was huge, crushing, worse than anything she had imagined in six years of anticipation of this ordeal. The surges in deceleration seemed astonishingly abrupt, violent. She could feel her internal organs sliding over each other, flattening against her spinal column. Her limbs felt as brittle as twigs, her muscles as limp as wet string; she didn’t dare move a limb. She didn’t seem to have the strength to draw in a breath, and she felt panic creeping over her as the oxygen in her lungs grew depleted.

  The colors leached out of the big clunky control panel in front of her, and walls of darkness closed in around her vision. It was hard even to blink, to relieve the dryness of her eyes. Her mouthpiece felt like an iron bar being forced against her jaw. Unable to see a chronometer, she tried to count, to reduce this experience to a finite time that must pass. A thousand and one. A thousand and two…

  She couldn’t concentrate. She lost count. She wasn’t even able to maintain the rhythm of the count.

  Starved of blood and oxygen, her brain was closing down. The darkness at the fringe of her vision closed in, like sweeping curtains.

  Then, as suddenly as it had mounted, the pressure faded. The weight on her chest was lifted off. She sucked in air, her chest expanding against emptiness.

  The glow of the plasma was fading. Beyond Jitterbug’s window there was a rusty orange glow. Already she was deep within the air-ocean of this drowned moon; above her was a hundred miles of murky aerosol haze, a hundred miles of cigarette smoke.

  For the first time in six years, Mott’s sky was no longer black.

  The fiery entry phase was already over. The G meter read nought point one four—Titan gravity, one-seventh of a G. Three minutes after leaving orbit she was falling, alone, towards a hidden landscape, at nine hundred miles an hour.

  Now, the first drogue parachute should deploy. It would burst from the parachute compartment in Jitterbug’s nose with a pyrotechnic bang, blowing away the apex cover of the compartment, and then open with a snap…

  Nothing happened.

  She checked her mission timer and G-meter against the checklist, still fixed to the control panel before her.

  The drogue should have opened by now. If the drogue didn’t open, neither would the main chutes.

  Shit, she thought. What did I miss?

  She punched the manual drogue deploy button.

  After a few seconds she heard the bang of the drogue’s pyrotechnics. The drogue chute hauled at the capsule, jolting her hard into her couch.

  Jitterbug’s velocity slowed—in thirty seconds and five miles—to three hundred feet per second, well below the speed of sound.

  A hundred miles up, the air temperature outside was minus 120 degrees C.

  Another bang. That had to be the mains, the three eighty-footer ringsails which would lower Jitterbug gently to the surface of Titan. Through the little docking windows above her Mott could see the main chutes as they unfolded, streaming upward lazily in the thickening air. The chutes were unbleached, to save weight; they were yellow, like three big dirty jellyfish.

  Jitterbug became a huge pendulum, swinging on a wide, slow path, suspended beneath the mains, in Titan’s feeble gravity taking all of forty-five seconds to complete a cycle; it was a slow, comforting rocking.

  She felt her heartbeat slow, the moment of panic over.

  What did I miss?

  The Command Module was supposed to be controlling its own sequence of operations, now, as it went through its cycle of pyrotechnic explosions and parachute deployment. The main Arming Timer fired the pyrotechnics in a hard-wired sequence keyed to deceleration measured by a G-switch. The idea was to improve reliability, to provide a hardware-managed timelining that was independent of the Command Module’s computer processor and software.

  That was the idea, anyhow. She scanned back up her checklist.

  … Oh.

  She had been supposed to enable the whole system by throwing a couple of switches, to start the Titan landing system and disable the reaction control shutdown. She should have done that just after emerging from the heavy deceleration of the entry phase.

  She hadn’t. Maybe if she hadn’t been alone, she wouldn’t have missed it.

  So far it all seemed to be working, however. Except for her human error. Everything—her life—depended on how robust the reworked systems now proved to be, in the face of that mistake.

  She heard a rattle of solenoids; the capsule jerked about, startling her.

  It was the reaction control thrusters. They were still firing, trying to damp oscillations in the vehicle’s attitude, their action futile so deep in the atmosphere. It shouldn’t be happening. The RCS should have been disabled, at the start of the auto sequence that she’d missed.

  She snapped the RCS switch to OFF The solenoid rattle died immediately.

  The fact was, she was off the nominal program, now.

  By failing to enter that command to start the new customized automated sequence, she was having Jitterbug follow fallback paths. Fifty-year-old logic paths, designed, originally, for entry into Earth’s comparatively benign atmosphere. And although those logic paths had been tested out, there was no way they could have been made as safe as the primary path…

  She felt a flicker of unease.

  For fifteen minutes Jitterbug drifted under its main chutes, its speed gradually dropping. It was as if she was suspended above the surface of Titan in the metallic gondola of some balloon.

  She monitored the Command Module’s clunky systems, waiting for the next glitch, the next anomaly.

  She tried the periscope display. This was an oval piece of glass about a foot across set in the middle of the instrument panel before her. The periscope gave her a fish-eve view of the surface, looking down past the scorched white tiles of the hull:

  A layer of thin white cloud, like cirrus, came ballooning up around her. Methane ice. Once through that, she looked down on a rolling, unbroken layer of thick, dark methane-nitrogen clouds, hiding the murky ground below. The clouds were almost Earthlike: fat, fluffy cumuli…

  She could turn the periscope this way and that, with a little joystick in front of her. She imagined the tiny lens poking out of the hull and swiveling, above her head. The periscope had actually been cannibalized from an antique Mercury capsule, one of the original production run, which had been designed without windows; the periscope had been installed after protests from the astronauts to give them a view.

  Even the effort of twisting the joystick seemed to deplete the muscles of her hand. It was going to take her a good while after landing before she had acclimatized enough to clamber out of her couch and try cracking the hatch.

  After fifteen minutes the Command Module’s velocity was reduced to a hundred and twenty feet per second, and she was ninety miles above the surface. Now, with a crack of p
yrotechnics above her, the main chute was jettisoned.

  For an instant she was falling freely.

  And then the final chute, the paraglider, opened up; and she was jolted back into her couch once more.

  She let out her breath. She was through another command sequence which hadn’t gone wrong. Maybe she would live through this vet.

  The paraglider was just a shaped canopy, marginally steerable. It was another old idea, that had been tried out for Gemini. Thus, a Gemini paraglider and a Mercury periscope should let Mott fly an Apollo capsule, like Dumbo, down to the wreck of a Shuttle orbiter, a billion miles from home…

  Fifty miles above the ground, Jitterbug was immersed in thickening orange petrochemical haze. But the sun was still plainly visible as a brilliant disc, surrounded by an aureole, a yellow-brown halo.

  Mott swiveled her periscope until Saturn was fixed at the center of her oval window. But already the water-color yellow wash of Saturn’s surface was becoming fainter, obscured by the uniform brown smear of the smog. She stared into the periscope until at last the planet’s fat, elliptical outline was lost, as if fading out on a poorly tuned TV screen, and the cloud closed over.

  The sun, she saw, had vanished too. She had watched her last dawn, her last sunset. She was stuck clown here, for good or ill.

  Forty miles high, Jitterbug fell out of the condensate haze, into a layer of clearer air. Then, at thirty miles, it penetrated the fat methane clouds. The temperature was close to its minimum here, at minus two hundred degrees Centigrade. The clouds were dark, brooding, as if stormy. Deep within the clouds, the cabin grew dark, and the lights of the instruments on the panel before her seemed to glow brighter.

  Suddenly the altimeter kicked in. She was at a hundred and fifty thousand feet, it said. Feet, not miles: the measure of an aircraft, ballooning down through Titan’s atmosphere.

  Jitterbug emerged from the base of the clouds, which now hid the orange sky.

  Gradually, through mist and scattered cloud, for the first time, Titan’s surface became visible to human eyes.

  … Fluffy clouds of ethane vapor lay draped over glimmering circular lakes, which were cupped in continents of water ice. The liquid in those lakes was black to her vision, the round ponds puncturing the red-brown carcass of Titan like neat bullet-holes. It might have been a high-altitude view of Earth’s surface, though rendered in somber, reds and browns, a twilit panorama…

  She reached out and took hold of a handset on the panel in front of her. The handset controlled the paraglider, by tweaking at its cables. Using this she ought to be able to fly the Command Module right in to the orbiter, with an accuracy of—the designers had told her—a hundred yards or so. And in the limited VR sims they’d set up, she’d consistently scored better than that, getting down to within thirty or forty feet of the target.

  But first she had to spot her target, the orbiter on the surface.

  She peered anxiously into the periscope. The surface of Titan—in the fish-eye view, bulging towards her—was resolving into a landscape of mud and crater lakes. The smaller lakes, a couple of miles across, were simple circles. But she could see central peaks protruding from the centers of some of the larger lakes, their shores washed clean of muddy slush.

  And now Jitterbug drifted over a pair of giant craters, each perhaps fifty miles across. In one of these the central peak seemed to have broadened into a dome, so that the ethane pool was contained in a thin ring around a central island. But she could see a pit at the center of the dome, itself containing a small pool, so the whole structure had a bull’s-eye shape, with the solid circle and band of dark fluid contained by the circular crater rim. And in the second of the big craters, the outer annulus of fluid seemed to be heaped up against one wall of the crater—perhaps by some tidal effect—so that the lake was in the form of a semicircular horseshoe.

  The landscape was strange, even the shape of the lakes bizarre.

  This is Titan, she reminded herself with a shiver. You are a billion miles from home. And there’s nothing in human experience to guide you as to what you’ll find here.

  The Command Module shuddered, the hull groaning.

  She gripped her seat, hard. She could feel the hard metal frame through the thickness of her pressure suit gloves. The Command Module felt fragile around her; it was like being inside some flimsy aluminum bathysphere, descending into this murky orange ocean.

  Now she was suspended over a mountain range, wrinkles in the glimmering surface. The peaks were exposed, dark gray water ice bedrock, and the uniform orange coating of the lower ground lay in streaks that followed the contours of the mountain, like snow runs.

  The area looked familiar from Rosenberg’s Cassini maps. She turned the periscope, jerking it from one side of the ship to the other.

  There. A little way away from the range was a crater lake, the muddy liquid pooled in the shape of a cashew nut.

  It was Clear Lake: just like the radar images. And Mount Othrys must be somewhere in that range below her.

  … She caught a glimpse of white, embedded on the dried-blood surface like a splinter of bone protruding from a wound.

  It was a delta-shape. Discovery.

  She grinned fiercely, her spirits rising for the first time since Saturn had disappeared. She wouldn’t even have to steer the paraglider much; now all she had to do was glide her way down this last ten thousand feet and—

  There was a snap, somewhere in the wall high above her.

  Murky air billowed into the cabin, above her face. There was a stink, of swamps and marshes and…

  And methane. Titan air. And, mixed in with it, the sharp tang of nitrogen tetroxide, oxidizer from the RCS.

  She couldn’t believe it; she sat staring as the orange mush billowed down towards her. Following some antique command, the cabin pressure relief valve had opened. The valve was a two-inch nozzle designed to let in warm Pacific air, for returning Moon voyagers. It was not supposed to open on the way down to Titan.

  It was the failure she had been waiting for. This had to be some consequence of her failing to follow the correct automation sequence earlier. Another untested logic path. But why the hell hadn’t that damn valve simply been welded shut?

  It was a multiple failure. Multiple failures always got you, in the end.

  And while she lay here and thought about it, she had sucked in a lungful of freezing, toxic Titan air…

  She closed her mouth and eyes and pulled her faceplate down. It snapped into place, and she felt a cool blue blast of oxygen on her face. She breathed out, trying to empty her lungs. But that, she realized, was only going to start the methane and nitrogen tet circulating in her life support.

  The stink of swamp gas was overwhelming. And the nitrogen tet seemed to be burning at her lungs and eyes; she could barely see.

  She considered trying to find some way to close that relief valve. But now she could barely see the instrument panel.

  Anyhow, maybe it was better for the oxygen in the cabin to be overwhelmed by Titan air. It that methane caught a spark, Jitterbug would explode.

  She was coughing, her throat and lungs aching.

  The descent was nearly over, anyhow.

  The cold air of Titan wrapped over her limbs. She found herself shivering already. When she got to the ground, she’d have to move quickly to get to the heated EVA suit. She rehearsed the moves she would make. Stand up, as best she could, and reach under the couch for the big net bag there; haul out the suit…

  Jitterbug crashed into the tholin slush.

  The fall was no more severe than if Jitterbug had been dropped on Earth from five or six feet. But to Mott it felt like a huge impact, an astonishing eruption of agony throughout her bruised body.

  … And now the Command Module tipped to the right. She could feel the roll, see the orange-black landscape wheel past the windows. Perhaps the paraglider hadn’t come loose, and was dragging jitterbug over. Or perhaps she had landed on some kind of slope, a crater wall m
aybe, and was rolling.

  Orange-brown mud splashed across the glass of the windows to her right, and turned them dark. Mott found herself hanging there in her straps, with cabin trash raining down around her: bits of paper, urine bags, discarded washcloths. The Stable 2 position, she thought. Upside down. One whole side of Jitterbug must be buried in the icy slush of Titan.

  For a moment there was stillness, a cramped creaking as the hull cooled.

  Then a window to her right cracked in two. Orange-black slush forced its way into the cabin, flowing, viscous.

  Mott, suspended, began coughing again.

  She was stuck in her seat. She couldn’t move. She was going to freeze. Help was two hours away, or a billion miles, depending on how you looked at it.

  When the Titan slush lapped against her legs, she could feel the cold of it seep into her bones.

  No footprints and flags for me, after all. But I got here. I got to touch Titan.

  The slush was rising. It would reach her head in a few seconds. She tried not to struggle.

  So quickly, it was over.

  Heat and cold, she thought; fire and ice. That’s what separates Siobhan and me: fire and ice, at the extremities of the Solar System—

  The slush forced its way through her faceplate, driving shards of plexiglass before it.

  After its muddy splashdown, Command Module CM-115A settled deeper into the icy slush of Titan, its aluminum hull creaking as it cooled.

  A wall-mounted camera peered at Benacerraf, as she lay in her couch, making history. She felt flat, deflated, battered by the events of the entry, the loss of contact with Nicola.

  But she had her role to play.

  She said, “Houston, Bifrost. Tartarus Base here. We have landed.”