Rosenberg had reached a kind of ultimate logic, she thought. He must be spending his walking time addressing the final question science couldn’t answer, in this godless age:

Why bother to live at all?

But that wasn’t really his problem, of course. She’d never met anybody who knew themselves worse than Rosenberg. Except maybe Bill Angel.

Rosenberg’s problem was that he was alone. He’d come all the way to Titan, because of that, and now he was here, and he was still alone.

“Rosenberg,” she said.

“What?”

“If it’s any consolation, I need you. I’ve never depended on anyone so much in my life. No human has been more dependent on another, than you and I.”

“More primate logic, Paula?”

“We are primates, asshole.”

“This is just perlerorneq, Paula.”

“Huh?”

“The winter blues. An Inuit word. Goodnight, Paula.”

“Goodnight.”

They walked into the crater basin, and loaded the sleds with as much crater-bottom tholin as they could carry.

They turned, for home.

The journey didn’t get any easier. Her sled was even heavier than when they had set off from Tartarus, laden with bags of frozen urine and feces, and with canvas-wrapped bundles of kerogen-soaked gumbo — so they hoped — from El Dorado. And as Rosenberg had weakened, she had been forced, surreptitiously, to transfer some of his load to hers.

Once again Titan’s slow rotation had taken this hemisphere into night. They would stay in darkness, in fact, until they reached Discovery. So she walked on, with only a splash of light from her helmet lamp ahead of her, and the faintest of diffuse orange glows from the haze above and around her.

The pain in her feet dominated her mind. It was as if she was trapped in some tunnel, walled in by pain, receding ahead and behind her to infinity.

She tried to objectify the pain itself.

She imagined the pain as outside her, even as a living thing, a malevolent creature. It was a red-hot poker embedded in her bone, a crucifixion nail driven into her foot, a gigantic invisible snake-head with its jaws clamped over her foot…

If only there was some way she could make it stop. If she was on some dumb stunt of a polar expedition, she’d call in the relief planes right now. If she was subject to some ghastly torture, she’d confess, give in, betray anybody or anything. Just to make this stop.

But through all this the pain was still there, lurking beneath the distracting superstructures she erected inside her head. And every time she slipped or caught her boot on a ridge in the ice the pain would come bubbling up, overwhelming her conscious thought, raw and primeval.

She kept getting ahead of Rosenberg. Each time she stopped, it seemed an increasing wait before his circle of helmet lamp light came weaving across the ice towards her.

The journey just went on, without meaning save survival, day after day.

After fifteen days out, they got back to Tartarus Base.

In the light of her helmet lamp, the orbiter and Command Module, side by side, were just mounds in the gumbo, their surfaces streaked by bruised-purple tholin deposits. They were unrecognizable as man-made artifacts save for their symmetry of construction.

Somehow, Benacerraf was disappointed. She’d been building this place up in her mind as her home, like a cliche of a family-Christmas fireside, somewhere warm and safe that would shelter her. But it was no such thing, of course; all there was here was a couple of downed spacecraft, a tiny, shivering farm, a cooling nuclear pile.

She unbuckled her traces. She retraced her tracks, back towards Rosenberg. Her footsteps, in the dim yellow light of her helmet lamp, were shallow, infilling craters in the gumbo.

She got them both into the airlock. She cracked their suit seals and took off their helmets, boots and gloves. Rosenberg’s helmet came away with strips of skin and tufts of hair and beard clinging to the lining.

She led him through into the interior of the hab module. The air here was hot, thick and moist, hard to breathe, and so sterile it almost smelled antiseptic. Bizarrely, she found herself missing the warm, almost cozy suit-stink she’d been immersed in for two weeks.

She helped Rosenberg to one of the Command Module couches. He sat there like a melting, gumbo-streaked snowman, his bony hands dumped in his lap, his head slumped forward.

Benacerraf made her way to the far end of the hab module, her ruined socks leaving trails of sticky blood on the clean metal surfaces.

She stripped off her own suit. She was stiff all over, particularly in her lower back, shoulders and hips; it was painful to put herself through the contortions required to shuck off the suit’s layers. The inner layers clung to her damaged flesh; she had to tease the cloth and plastic away from her skin, trying not actually to break her epidermis or pull away scabs. The suit was worn and badly damaged in places. They’d been lucky the suits had worked to carry them so far — the EVA had been well beyond the suits’ design limits.

At last the suit lay as a heap of soiled Beta-cloth at her feet.

She stood naked, shivering despite the cloying warmth of the hab module.

She was skeletal, her ribs protruding under flat sacks she didn’t recognize as her breasts, her buttocks lumpy and flaccid, her knees and elbows hard knobs of bone. Her feet were a mass of lumpy, pus-filled growths and open frostbite wounds and scars. Crotch rot spread from the dark triangle of pubic hair, out over her thighs and belly, angry red. There were pressure sores where the harness had dug into her, and where her suit had chafed, over her hips, under her armpits and around her chest and waist. Her personal hygiene during the EVA hadn’t been too effective. Her upper legs and buttocks were flecked with yellow urine stains and smears of what looked like dried excrement, and there were patches of glaring red skin infections around her waist and legs, the parts of her body where she hadn’t been able, or willing, to reach.

She allowed herself two minutes to shower. The hot, clean water felt like acid on her skin; it was actually painful to have the layers of filth lifted from her ghost-pale flesh.

She padded to her quarters. She pulled on underwear, and an old Beta-cloth T-shirt and shorts. She tried to don her Beta-cloth slippers, but they wouldn’t fit over her swollen sores; so she wrapped old T-shirts loosely over her feet and bound them up with duct tape.

She gave herself a moment to run her hands over her belongings, her books and photos, anchoring herself once more in these relics of her life, her personality.

As an afterthought, she put on a facemask and a pair of surgical gloves. Then she made her way to Rosenberg.

He was still in his suit. She stood him upright. He felt disturbingly light. His head was a mess, the hair matted with filth and patchily bald; there were cracks around his mouth, nose and eyes that had opened into fissures as deep as razor slices, dribbling thin blood.

Slowly, she got him stripped. His undergarments were even more matted with waste and filth and blood than hers had been. It looked as if he had suffered some kind of dysentery attack and fouled his pants; when she pulled off the suit, hot stinking liquid flowed out over the clean floor of the hab module.

Benacerraf got his longjohns away from his arms and lowered them around his legs. A shower of skin fragments and pubic hair fell onto the metal at Rosenberg’s feet. His legs and groin seemed to have been stripped clean of skin, left raw and compressed into folds. His kneecaps were just ripples of flesh, his genitals rubbed raw. She could see deep wounds dug by the edges of the harness straps, and within the patterns of straps she found eruptions like small, festering boils.