He relaxed, with a rattling sigh, and lay still, collapsing into her arms with a slow-motion, low-gravity calmness. “You know, I learned a lot,” he whispered. “More than I expected.”

“You did good, Rosenberg.”

“But you know, I never figured out why…”

“What?”

“Why did it feel like this?”

She could feel his body settle, the internal organs relaxing and losing their tension; the last gases escaped from his stomach in a long, low fart.

She got him into the frigid ground only an hour later.

The grave was just a shallow ditch, scraped out of the gumbo, already infilling. His naked body lay at its base, thin, skeletal, glistening with the frozen water ice of his body.

Once again she had to find words to say over a corpse.

She checked her transmission link to Cassini. She wanted this moment to be sent to Earth. Maybe there was somebody there to listen; maybe not. If there was, maybe this would somehow help them.

“I’m sorry I didn’t have a flag to wrap you in, Rosenberg,” she said. “Anyhow, I know this was what you wanted, in spite of what you said. And if you think I was going to have your sorry ass circulating around my ecosystem, you got another think coming.

“Casting a shadow across five aeons.Maybe you will at that. You did good, Rosenberg.”

I guess that will do, she thought.

She threw a handful of Othrys ice crystals into the grave, and began to drag her snowshovel over the gumbo, filling in the shallow pit.

In the last days she spent a lot of time in the CELSS farm, trying to stabilize it as much as she could. She kept power supplied to the farm, and left it seeded with a new crop, of wheat, barley and lettuce.

She felt a great responsibility for the drawn, etiolated little plants here. They were, after all, the only living things other than herself on this whole moon, and she felt loyal to them, and regretted she was abandoning them to die.

But there wasn’t much she could do for them. She figured the CELSS farm might last without human intervention a few weeks, before a pump broke down, or a nutrient pipe clogged, or a short burned out half the lamps, or some runaway feedback biocycle caused the miniature ecology to crash.

Even if by some miracle that didn’t happen, eventually the power from the Topaz reactors in Discovery’s cargo bay would fail. The lights would dim, and the last, spindly plants would finally die, as Titan’s cold broke in.

She took spare seeds and wrapped them in airtight bags. She buried them, under a marker, in the gumbo outside Bifrost. That way, perhaps they would survive, deep-frozen, until Discovery’s next visitors came this way, whatever became of her.

She spent a last night in the hab module. She took a long, hot, luxurious shower, extravagantly spending, the reactors’ reserves of energy.

She tried to read a book on her softscreen, but could barely concentrate. She kept on thinking that this would likely be the last book she ever read. The words seemed just a foolish dancing, against dark emptiness.

She put the softscreen aside.

She looked at her images of Jackie and her grandchildren. She stared into the sunny photos, trying to will herself into the pictures with her family.

She slept well, in her quarters, with the lights off and the door closed, shut in against the shells of emptiness around her: the deserted hab module, the empty moon, the billion miles separating her from Earth.

When she woke she ate a gigantic breakfast, using up a lot of stores: dried apricots, an irradiated breakfast roll, rehydrated granola with blueberries, ground beef with pickle sauce, noodles and chicken, stewed tomato, pears, almonds, drinks of grapefruit and strawberry.

She went to the hygiene station and took a long, slow, luxurious dump. She cleaned herself with antiseptic wet-wipes.

She stripped naked. She folded up her Beta-cloth clothes neatly and put them away in a drawer. She washed one last time, then put plasters and bandages over the places where she knew to expect problems from cold and pressure sores: her toes and ankles and the sides of her feet, her hips, stomach, chest and shoulders. She put cream — all that was left was the hemorrhoid ointment — over her groin, in anticipation of crotch rot.

She pulled on her suit. She took great care over each layer; she wouldn’t get another chance to fix it, and she would hate to go to her destiny with a fold in her underwear rucked up her ass.

Inside the suit layers, duct-taped to the fabric, she stored Rosenberg’s canister of bacteria samples — protected there against the cold — and a little packet of photographs, old-fashioned hard-copy images, of Jackie and the kids.

She sealed up her helmet, gloves and boots, and ran methodically through the suit checklist fixed in its ring binder to her arm. She went through the list twice. In a way her biggest dread, now she was alone, was that without anyone to check her she would miss out some crucial step, kill herself through carelessness.

She looked around the hab module one last time before leaving it. It was clean, tidy, everything stowed away, as if ready for reoccupation. She felt obscurely proud; she’d remained civilized to the end.

Just like Captain Scott.

She slipped on her Apollo hull-metal snowshoes and stepped out into the gumbo. The tholin slush sucked at her feet with its familiar stickiness, and she felt Titan cold immediately seeping through the layers of her suit.

She looked over Tartarus Base.

She could make out the delta shape of the grounded orbiter, with the cone of the Command Module alongside. The cover they had erected over the open cargo bay of the orbiter was still in place, the parachute fabric stiff and streaked with gumbo. In a final extravagant gesture she’d left the flood lights of Discovery’s flight deck burning; the yellow Earth-like light now glared out through tholin-streaked windows, shining over glimmering slush.

There was little geologic activity here; the ground was stable. Even the tholin deposition rate was slow. It might take a billion years, Benacerraf thought. But at last Titan would claim Tartarus, its patient tholin drizzle ultimately covering over the pyramidal peak of Apollo, Discovery’s big boattail. The spacecraft hulls would ultimately crumple and shatter, until nothing remained of this, the first human outpost on another planet, save a thin, isolated layer of metallic crystals, and a few anomalous deposits of organic residue.

She looked up, towards the marginally lighter horizon. She cut in her IR visor and made out the spark of light, pixel-blurred, that was the sun. From here, the entire orbit of Earth was a circle the size of a small plate held at arm’s length, with the planet itself — with all its freight of humanity, and hope and love and war and history — a dull-glowing bead on the rim of that circle, impossible to make out. She could hold up her bulky gloved hand and obscure the entirety of the orbit, the whole span of human experience before the Discovery expedition.

She buckled the Command Module couch harnesses around her. She dug her snowshoes into the gumbo and shoved. Immediately she felt twinges from the sites of the pressure sores she’d suffered last time, at her hips and chest and shoulders.

The sled came free of the clinging gumbo with a sucking noise. She staggered forward.

The sled was heavier, this time, than when she’d set out for her previous extended EVA with Rosenberg. This time, all the essentials — the tent, the recharged skimmer power cells, all her food and water — were stacked high on this one sled.

On the other hand, her food load was lessened. Just enough for a one way trip.