Titan

by Stephen Baxter

  “Attitude switches to inertial, panels F6 and F8. ADI error to median. ADI rate to median…”

  Mott reached for her hand controller, and pulsed the RCS jets. Benacerraf could hear the hard click of solenoids, feel the soft shudder of the little jets as they shoved at Discovery’s mass.

  The light started to change.

  As Discovery turned, the sun was crossing the window, right to left. It was a shrunken disc. Pale, yellowish light played directly into the cabin, the window struts casting long, sharp shadows over Benacerraf’s lap. False images sparkled in the scuffed plexiglass of her helmet visor.

  Diminished since Jupiter, the sun was still more brilliant than any star or planet seen from Earth, ten thousand times brighter than a full Moon. It was a little like looking directly into an approaching headlight.

  And now the limb of Saturn, a thin crescent, reached into the window frame. Precise and huge and intimidating, it reared up before the sun. It was a yellow arc, obviously flattened from the circular, blistered with turbulence. The colors were subtle, and she found she had to shield her eyes from the glaring yellow and white and green of the orbiter’s instrument lights.

  Saturn was no gaudy pyrotechnic display, but an autumn-color sculpture wrought of the soft light of the remote sun. It was, Benacerraf thought with a shiver, utterly unearthly.

  Mott had to turn the orbiter so it was flying tail-first. Discovery had accelerated as it had fallen into Saturn’s gravity well. Already deep within the planet’s magnetosphere the spacecraft was now plunging towards Saturn itself; it would make its closest approach over the dark side of the giant world, just a sixth of a Saturn radius above the cloud tops. And there, at the lowest point in the gravity well, the SOI burn would be initiated.

  After a six year space soak, the orbiter’s OMS engines, the small orbital maneuvering system, had to burn for a hundred minutes, sucking fuel and oxidizer out of the big supplementary tanks that were strapped to the orbiter’s wings, like two fat bomb pods, slowing the craft into a looping, five-month orbit around Saturn.

  The burn had to work. Otherwise, Discovery would not shed enough velocity to be captured by Saturn’s gravity. They wouldn’t make it to Titan. Not only that, the orbiter would be hurled onward in an involuntary slingshot, towards the stars.

  Benacerraf had privately calculated they might make it one-tenth of the way to the orbit of Uranus, the next giant planet, before their consumables finally gave out.

  And—although it hadn’t been expressed—she was sure nobody had forgotten that it was the OMS burn which had been ultimately catastrophic on Columbia’s last flight.

  But whether they survived all this or not, this battered old space truck had come a hell of a lot further than had been dreamed by those old guys who had devised the Shuttle in the 1970s.

  Saturn drifted out of the window frame.

  “Maneuver to burn attitude complete,” Mott said.

  Benacerraf forced her attention to the checklist, and to the instruments on the panels before her. She compared the attitude shown on the CRT display with that given by the eight-ball, the attitude direction indicator. They matched each other and the predictions in the checklist, to several decimal places.

  “Good work, Niki,” she said. “Maneuver complete, confirm.”

  “All right,” Mott said evenly. Under strain, she was visibly turning her attention to the next obstacle.

  One step at a time, Benacerraf thought.

  Mott said, “Let’s go for single APU start.”

  “Rog. Number one APU fuel tank valve to open. Control switch to start/run, number one APU.”

  “Confirm hydraulic pressure indicator one is green,” Mott said.

  “Hydraulic circulation pump switches to off, one, two, three.”

  “… Okay, we have single APU start.”

  “Good. We’re doing fine, Niki. Now. Arm the engines.”

  Mott reached forward, and over her head. “Auto pilot to auto. OMS helium pressure switches to GPC, left and right engines. OMS engine switches to arm.” She looked across at Benacerraf “Engines armed.”

  “Good girl.”

  The routine, the checklists and procedures for just another OMS burn, was comforting. It allowed her to forget what they were doing here: firing rocket engines to go into orbit around Saturn, for God’s sake.

  “One minute to the burn,” Rosenberg said.

  Mott reached forward to the computer keyboard. She pressed the EXEC key, and the computer began its countdown to the burn.

  … And suddenly, light exploded into the flight deck, for Discovery was sailing above the plane of Saturn’s rings.

  To Benacerraf the rings looked like a broad sheet of colored light, as if Discovery were a mote of dust flying high above some elaborate laser display. This close, it was impossible to see their full extent; Benacerraf could see only a portion of the ring disc framed in her window. Though the lighting was dim, the different bands within the rings were clearly visible, distinguishable by their faint, yellow-brown colorations, separated by dark gaps.

  “Incredible,” Rosenberg said. Benacerraf could see the rings reflected from his visor, precise stripes of smoky, washed-out light. “It looks like an artifact, doesn’t it? Something made… But if those rings were transplanted home, they would fill up the space between Earth and Moon. Think of that. And look.” He pointed. “You can see a moon, buried in there in the structure. That’s the E ring; the moon must be Enceladus, I think. See how bright it is?”

  After some searching she made out the moon, barely discernible as an icy spark, suspended in one of the dark ring gaps.

  The giant shadow of Saturn, blunt and physical, lay across the rings, casting a precise terminator across their structure: perhaps the longest straight line in the Solar System. Earth itself could have rolled around that ring disc, like a ball bearing on a plate. Space here was filled by huge shapes, Benacerraf thought, like gigantic machinery.

  Mott said, “Ten seconds to the burn. Five, four, three, two, one.”

  The orbiter shuddered, and Benacerraf thought she could hear a remote bass roar, transmitted through the structure of the craft.

  “Ignition,” Mott shouted.

  “Copy OMS ignition.”

  “Building up to full thrust. Point zero five G. Point zero eight. Zero nine. Stabilizing there…”

  Benacerraf felt herself sink back into her seat. It was as if the orbiter was tipping up, and she was lying on her back in her couch. The metal of her couch, folds in the fabric of her pressure suit, dug painfully into her flesh. And now there was a dark fringe to her vision, as if she was looking along a tunnel. The colors seemed to leach out of the control panel before her.

  My God, she thought. I’m graying out.

  She was experiencing acceleration, for the first time since the CELSS farm had been transferred to the centrifuge, more than three years ago.

  The checklist fell from her lap against her chest, landing with a thud that knocked the air out of her. Her arms were across her chest, and she could feel where they lay, like concrete beams compressing her lungs, her gloved hands huge and massive. And her internal organs, her heart and guts and lungs, were settling out, moving to some new equilibrium inside her. She couldn’t have moved, reached up to a control, to save her life.

  And this is only a tenth of a G. We’ll be incapacitated on the surface of Titan. Even if we survive the reentry.

  “Holy shit,” Mott said. Her voice was remote, weak.

  Benacerraf tried to turn her head to see Mott, but her skull felt as heavy as a ball of concrete. “Take it easy, kid,” she said. “Discovery can fly itself; we don’t have to do a damn thing.”

  The burn went on and on.

  Discovery sailed into the shadow of Saturn. The darkness seemed cool, immense, deepening their isolation. It was the first time in six years that the orbiter had not been bathed in sunlight.

  And now, with the instruments in the payload bay gaping at the planet, Di
scovery fell through the plane of the ring system. The rings were less than a mile thick, and at Discovery’s interplanetary velocity, the plane was crossed in a fraction of a second.

  Benacerraf, staring back along the path of Discovery, could see the shadowed rings above her. They were a huge roof of darkness, occluding the patchy stars. Here and there she thought she could see a gap in the ring system, a fine circular arc, full of stars. The bulk of the planet was to her right, a flat-infinite wall of shadowed cloud, just a sixth of Saturn’s radius away.

  Discovery was a fly circling the flank of an elephant.

  And now, as her eyes continued to dark-adapt, she saw that there was a patch of light tracking over the shadowed ceiling of the ring system: a diffuse circle, like the image of the sun seen through fog. It seemed to he matching the movements of Discovery.

  It was the light of Discovery’s engines—the burning of monomethyl hydrazine and nitrogen tet, hauled out here all the way from Earth, reflecting from the icy rings of Saturn.

  Then, as Discovery fell beneath Saturn’s equatorial plane, the diffuse glow faded out—

  There was a bang, sharp, muffled by the thickness of her helmet.

  It was gone so quickly she wasn’t sure if it had been real.

  “Niki. Did you hear that?”

  “No.” Mott hesitated. “But I felt something. A shudder.”

  A bang, a shudder. Put it together, Paula.

  Benacerraf felt fear gather like a sharp knot in her stomach But she was helpless, trapped in her seat by this minuscule gravity.

  The sounds of the cabin, the whir of the pumps and fans—already subdued by the helmet around her head—died away.

  “We’re losing pressure,” Mott said, her radio-transmitted voice full of wonder.

  Rosenberg started yelling. “Bill, close your eyes! Bill, if you can hear me, close your eyes!”

  … Light seeped into the cabin. Above Benacerraf, the ring-plane terminator was sliding into view, a geometrically straight line that could have stretched from Earth to Moon. The subdued gold-brown light of the rings soaked over her face.

  Rosenberg, with no reply from Angel, quit yelling.

  “What the hell happened, Rosenberg?”

  His voice was fragile. “We got hit by a ring fragment.”

  “But we’d already passed through the plane of the damn rings. And besides, we aimed for a gap.”

  “But the rings we see are patterns imposed on a complex, chaotic cloud of particles or dust and ice. This is a crowded part of space, Paula. We only came this deep because we needed the benefit of a low periapsis. We gambled we wouldn’t hit anything on the way through.”

  “Lucked out,” Nicola Mott said.

  Rosenberg pointed out, “Bill isn’t answering.”

  “How long until the burn’s done, Niki?”

  “Eight more minutes, Paula.”

  Rosenberg said, “Look, we have to go down and help Bill. Vacuum exposure will kill him.”

  Mott said, “Sit still.”

  “She’s right,” Benacerraf said wearily. “If you try to get out of your couch you’ll just fall the length of the cabin. Rosenberg, we have to wait.”

  “If we wait, we’ll find him dead,” Rosenberg said. “Damn it, Paula. If Bill is dead I hope you can live with yourself.”

  Benacerraf felt herself smile, tiredly. And there’s my function on this flight, she thought. Blame Paula: not that asshole Angel for endangering his own life by his madness and stupidity, not the confluence of forces which delivered us to this perilous point in space and time in such a fragile craft, not the malevolent God who put that fragment of primordial ice right in our path in the middle of the one and only traverse, by humans from Earth, of the rings of Saturn…

  At last the burn died.

  “Good burn,” Mott whispered. “Residuals were less than three tenths, on all axes.”

  “Welcome to Saturn,” Rosenberg said drily.

  The mid deck, like the flight deck, was in vacuum.

  The chunk of ring material had entered the mid deck at about waist height in the middle of the left hand wall, close to the galley. They found a neat round hole in the panel there, almost big enough for Benacerraf to push her finger into. And there was a matching hole in the floor, a few feet away, as if the particle had slanted down like a sniper’s rifle shot through the cabin.

  In fact, they had been lucky, she realized. It was a clean impact. A grain the size and speed that hit them could have done a lot more damage than just puncturing the pressure hull so cleanly.

  Ring material. At least, thought Benacerraf, it was more glamorous than the particle of flaked-off paint or frozen cosmonaut urine that had zapped them during their Earth flyby.

  It was simple to slap patches over the damage; soon the air pressure in the mid deck was restored.

  They found Angel sitting strapped into his fold-up seat. He had his pressure suit helmet on, with the visor closed; but the helmet wasn’t locked correctly at the neck. He was unconscious. Benacerraf could see his eyes were closed, his face contorted. And there was some kind of fluid, smeared over the inside of his visor, making it difficult to see inside.

  Rosenberg peered into Angel’s helmet, and shrugged. “He must have been exposed to vacuum for a few seconds, low pressure for a while longer. We got to get him out of here.”

  They manhandled Angel through the airlock at the rear of the mid deck, and into the hab module. Then the three of them went into the resuscitation routines they had rehearsed on Earth.

  With Benacerraf and Mott holding Angel’s limbs, Rosenberg checked for breathing, then braced himself against a wall and pumped four mouth-to-mouth breaths into Angel’s lungs. There was no response, so Rosenberg had the women move Angel around so that he could push his arms around Angel’s thorax and under his arms. He grabbed Angel’s elbows and worked them like a bellows, up and down, four times.

  “All right,” he said, breathless. “Now we got oxygenated air in his lungs.” He looked exhausted, his glasses sweat-streaked, as if he might pass out himself. “Now, the heart.” He felt for Angel’s carotid pulse. “Nothing. Niki, you’re stronger than me. Come around here.”

  Mott pulled herself behind Angel. She placed her left hand fist in Angel’s sternum and grabbed the fist with her other hand. She pulled Angel’s back against her chest, then compressed his sternum, hauling him hard towards her, counting. “One. Two. Three…” The idea was to squeeze the heart between the sternum and the thoracic vertebrae, and so push oxygenated blood through Angel’s body.

  At a count of twelve, Angel shuddered. He coughed, his throat dry and ragged.

  Later, Benacerraf was at a squawk box, listening to the insectile voice of a capcom, the words eighty minutes old. The capcom was enthusing about the images they had received during the Saturn closest approach. Already NASA was receiving requests for the commercial rights, and there were believed to be hundreds of illegal hacked-up VR copies running through their cycles even now, out in the net.

  She stared into a monitor.

  Discovery was receding from Saturn now, skimming back, briefly, towards the sun, and the planet was once more turning its full face to the spacecraft. The cloud bands were sharply distinguished, though more subtle and yellowish than Jupiter’s. Along the fringe of one band at the equator Benacerraf could see turbulence, oval clouds like cells. The rings themselves cast a shadow, a thin, complex line, over the milky equator of Saturn’s daylit hemisphere. The shadow was curved, an exercise in projective geometry. And the rings had a lacy, tenuous appearance, so that she could see the curve of the bright limb of the planet through their structure.

  There was nothing to compare to this experience.

  This was not, she thought, even like traveling from Earth to Moon, from one closed-up sphere to another. They had journeyed for years, into the huge outer wastes of the Solar System, and entered orbit around this metahuman artifact, this structure of rings and spheres that could fill up the Earth-M
oon system.

  It is the dream of a million years, she thought, to be here and see this.

  Rosenberg drifted in, and took her through Angel’s injuries.

  “… Paula, you have to understand the human body is not designed to withstand vacuum. Basically the internal pressure turns it into a kind of low-tech bomb. All Bill’s internal material tried to escape, through his skin, the orifices of his head and body. Bleeding everywhere. His lungs arc torn. His blood vessels have been leaking. A few more seconds and he would have drowned in his own blood. His blood must have been close to boiling in his veins.”

  “Will he live?”

  Rosenberg shrugged. “Sure. For a while. We all will, for a while. But if he was at home he’d be hospitalized.”

  “We aren’t at home.”

  “And, Paula—”

  “What?”

  “His brain was starved of oxygen. I don’t even know how long for.”

  That helps, she thought bleakly.

  “What was that fluid, on the inside of his visor?”

  “The clear stuff?” His face was neutral. “Oh, that. I did tell him to keep his eyes shut. His left eye ruptured, and—”

  Benacerraf felt bile pool at the back of her throat. She made it into the waste management area in time to throw up, violently, into the commode.

  She wiped her mouth on a wet-wipe, the antiseptic stinging her tongue.

  In his quarters, Angel was waking up. He was starting to scream.

  Book Four

  GROUND

  TRUTH

  A.D. 2014–A.D. 2015

  Voyager One flew high above the plane of the ecliptic, that invisible sheet in space which contains the orbits of the major planets of the Solar System.

  Voyager was a spindly dragonfly construction, of booms and struts and instrument platforms, and a huge antenna which pointed back at Earth. Built around a compact ten-sided box, it weighed about a ton, and was big enough to fill a small house.

  During its long mission, it had visited both the Solar System’s largest planets, Jupiter and Saturn. The gravitational fields of those worlds had flung Voyager onward at such a high speed that it had broken the bonds which once tied it to the sun.