Stephen Baxter: Xeelee: Endurance

We climbed up through the hatch in reverse order from how we had come in: Poole, Dzik, myself, then Miriam. The gravity, a seventh of Earth’s, was close enough to the Moon’s to make that part of the experience familiar at least, and I moved my weight easily enough. Once outside the hull, lamps on my suit lit up in response to the dark.

I dropped down a metre, and thus drifted to my first footfall on Titan.

The sandy surface crunched under my feet. I knew the sand was water ice, grains hard as glass in the intense chill. The sand was ridged into ripples, as if by a receding tide, and pebbles lay scattered, worn and eroded. A wind buffeted me, slow and massive, and I heard a low bass moan. A black rain smeared my faceplate.

The four of us stood together, chubby in our suits, the only humans on a world larger than Mercury. Beyond the puddle of light cast by our suit lamps an entirely unknown landscape stretched off into the infinite dark.

Miriam Berg was watching me. ‘What are you thinking, Jovik?’ As far as I know these were the first words spoken by any human standing on Titan.

‘Why ask me?’

‘You’re the only one of us who’s looking at Titan and not at the gondola.’

I grunted. ‘I’m thinking how like Earth this is. Like a beach somewhere, or a high desert, the sand, the pebbles. Like Mars, too, outside Kahra.’

‘Convergent processes,’ Dzik said dismissively. ‘But you are an entirely alien presence. Here, your blood is as hot as molten lava. Look, you’re leaking heat.’

And, looking down, I saw wisps of vapour rising up from my booted feet.

We checked over the gondola. Its inner pressure cage had been sturdy enough to protect us, but the external hull was crumpled and damaged, various attachments had been ripped off, and it had dug itself into the ice.

Poole called us together for a council of war. ‘Here’s the deal. There’s no sign of the envelope; it was shredded, we lost it. The gondola’s essential systems are sound, most importantly the power. The hull’s taken a beating, though.’ He banged the metal wall with a gloved fist; in the dense air I heard a muffled thump. ‘We’ve lost the extensibility. I’m afraid we’re stuck in these suits.’

‘Until what?’ I said. ‘Until we get the spare balloon envelope inflated, right?’

‘We don’t carry a spare,’ Bill Dzik said, and he had the grace to sound embarrassed. ‘It was a cost-benefit analysis—’

‘Well, you got that wrong,’ I snapped back. ‘How are we supposed to get off this damn moon now? You said we had to make some crackpot rendezvous with a booster pack.’

Poole tapped his chest, and a Virtual image of Harry’s head popped into existence in mid-air. ‘Good question. I’m working on options. I’m fabricating another envelope, and I’ll get it down to you. Once we have that gondola aloft again, I’ll have no trouble picking you up. In the meantime,’ he said more sternly, ‘you have work to do down there. Time is short.’

‘When we get back to the Crab ,’ Bill Dzik said to Poole, ‘you hold him down and I’ll kill him.’

‘He’s my father,’ said Michael Poole. ‘ I’ll kill him.’

Harry dissolved into a spray of pixels.

Poole said, ‘Look, here’s the deal. We’ll need to travel if we’re to achieve our science goals; we can’t do it all from this south pole site. We do have some mobility. The gondola has wheels; it will work as a truck down here. But we’re going to have to dig the wreck out of the sand first, and modify it. And meanwhile Harry’s right about the limited time. I suggest that Bill and I get on with the engineering. Miriam, you take Emry and go see what science you can do at the lake. It’s only a couple of kilometres’ – he checked a wrist map patch and pointed – ‘that way.’

‘OK.’ With low-gravity grace Miriam jumped back up to the hatch, and retrieved a pack from the gondola’s interior.

I felt deeply reluctant to move away from the shelter of the wrecked gondola. ‘What about those birds?’

Miriam jumped back down and approached me. ‘We’ve seen no sign of the birds since we landed. Come on, curator. It will take your mind off how scared you are.’ And she tramped away into the dark, away from the pool of light by the gondola.

Poole and Dzik turned away from me. I had no choice but to follow her.

Walking any distance was surprisingly difficult.

The layered heat-retaining suit was bulky and awkward, but it was flexible, and in that Titan was unlike the Moon with its vacuum, where the internal pressure forces even the best skinsuits to rigidity. But on Titan you are always aware of the resistance of the heavy air. At the surface the pressure is half as much again as on Earth, and the density of the air four times that at Earth’s surface. It is almost like moving underwater. And yet the gravity is so low that when you dig your feet into the sand for traction you have a tendency to go floating off the ground. Miriam showed me how to extend deep, sharp treads from the soles of my boots to dig into the loose sand.

It is the thickness of the air that is the survival challenge on Titan; you are bathed in an intensely cold fluid, less than a hundred degrees above absolute zero, that conducts away your heat enthusiastically, and I was always aware of the silent company of my suit’s heating system, and the power cells that would sustain it for no more than a few hours.

‘Turn your suit lights off,’ Miriam said to me after a few hundred metres. ‘Save your power.’

‘I prefer not to walk into what I can’t see.’

‘Your eyes will adapt. And your faceplate has image enhancers set to the spectrum of ambient light here . . . Come on, Jovik. If you don’t I’ll do it for you; your glare is stopping me from seeing too.’

‘All right, damn it.’

With the lights off, I was suspended in brown murk. But my eyes did adapt, and the faceplate subtly enhanced my vision. Titan opened up around me, a plain of sand and wind-eroded rock under an orange-brown sky – again not unlike Mars. Clouds of ethane or methane floated above me, and beyond them the haze towered up, layers of organic muck tens of kilometres deep. Yet I could see the sun in that haze, a spark low on the horizon, and facing it a half-full Saturn, much bigger than the Moon in Earth’s sky. Of the other moons or the stars, indeed of the Crab , I could see nothing. All the colours were drawn from a palette of crimson, orange and brown. Soon my eyes longed for a bit of green.

When I looked back I could see no sign of the gondola, its lights already lost in the haze. I saw we had left a clear line of footsteps behind us. It made me quail to think that this was the only footstep trail on all this little world.

We began to descend a shallow slope. I saw lines in the sand, like tide marks. ‘I think we’re coming to the lake.’

‘Yes,’ Miriam said. ‘It’s summer here, at the south pole. The lakes evaporate, and the ethane rains out at the north pole. In time it will be winter here and summer there, and the cycle will reverse. Small worlds have simple climate systems, Jovik. As I’m sure a curator ought to know . . .’

We came to the edge of the ethane lake. In that dim light it looked black like tar, and sluggish ripples crossed its surface. Patches of something more solid lay on the liquid, circular sheets almost like lilies, repellently oily. The lake stretched off black and flat to the horizon, which curved visibly, though it was blurred in the murky air.

It was an extraordinary experience to stand there in an exosuit and to face an ocean on such an alien world, the sea black, the sky and the shore brown. And yet there was again convergence with the Earth. This was, after all, a kind of beach. Looking around I saw we were in a sort of bay, and to my right, a few kilometres away, a river of black liquid had cut a broad valley, braided like a delta, as it ran into the sea.