Building the boat — designing it in the relative warmth of the hab module, cutting and shaping the base of Jitterbug — had actually been fun, in a home-workshop kind of way. Working those hours with Rosenberg, most of them in a companionable silence, had been among the happiest Benacerraf had known since leaving Earth. For once in this mission they’d had a finite, well-defined goal, and the means to achieve it.

But now, that they’d hauled the thing down here to the lake, it looked absurd, flimsy, a lashed-up improvisation. Which, of course, it was.

Benacerraf lined up with Rosenberg behind the boat. In her multilayer suit it was difficult to bend, and she struggled to close her thick gloves around the half-inch-thick rim of the boat’s wall. But when they overcame the friction of the gumbo and got up a little momentum, the boat coasted easily down the beach.

The boat slid into the ethane without a splash, and came to rest a couple of feet from the edge of the beach. It bobbed, eerily slowly, and concentric oily swells rippled away from its circumference, fat and massive.

Now Rosenberg wrapped the end of the boat’s steel mooring cable around his waist, and stepped back a few yards from the ethane’s edge. He kicked off his snowshoes and let himself sink into the gumbo, anchoring himself there. “Okay, Paula. I’ll pull you back at the first sign of trouble. The shallows should be okay, but that boat won’t be able to withstand any problems in deeper water. I mean, ethane. And, Paula. Whatever you do, don’t fall in. Don’t even sit down. That ethane lake has a much bigger heat capacity than your ass, it will give you one cosmic case of hemorrhoids…”

“I’ll bear it in mind, Rosenberg.”

She took off her snowshoes, and lifted them carefully back up the beach. Then she hauled on the cable to pull the boat a little closer to the shoreline, to minimize the ethane wading she would have to do.

She stumbled through the shallow ethane to the boat. As fast as she walked, the stabbing cold of the liquid pierced the multiple layers of her heated boots.

She stepped over the boat’s foot-high wall, and moved to the center of the boat. The little vessel rocked back and forth with slow grandeur, and she could hear a slow, sombre sloshing from the liquid around its hull.

She looked down at her feet. Droplets of ethane fizzed as they boiled away from her boots. The rocking steadied, slowly.

Rosenberg was climbing further back up the beach, stepping backwards, making sure his footing in the slush was secure. He sent waves rippling up and down the steel cable. The cable moved with languorous, snakelike grace in the low gravity; but it sliced through the low-density ethane liquid as if it wasn’t there. And where the cable penetrated the liquid Benacerraf could see a puncture in the heavy meniscus, surface tension hauling ethane up the steel Rosenberg pressed a stud on his chest panel to take photographs with the digital Hasselblad mounted there. “The boat is riding well. You’ve dipped into the liquid by no more than a few inches, under the combined weight of the boat itself, you, and the equipment…”

“Just as you calculated.”

“Just as I calculated. The density of the ethane—”

“Archimedes’ principle applies, even on Titan. I do understand, Rosenberg.”

“Sorry. Good luck, Paula.”

“Yeah.”

Benacerraf stepped to the rear of the boat and picked up the paddle. This was just another piece of Jitterbug hull, a curved shovel shape, fixed to a bar which had once been a couch strut. Feeling self-conscious, she leaned over to dip the paddle blade in the liquid.

She waved the paddle to and fro, in the ethane. There was little resistance to her motion, and the blade cut smoothly through the fluid without turbulence, but she could feel how the ethane was being cupped by the paddle.

With painful slowness, the boat inched away from the shore.

She was soon panting with the effort of waving the paddle. As she couldn’t sit down she had to lean over the side of the boat to reach the liquid, and that was making her back and arms ache. Her suit was too stiff for rowing, a task for which it had never been designed. And besides, she knew her muscles still hadn’t recovered from their extensive space soak. She made a mental note that they would need a longer handle the next time they tried this stunt.

Despite all this, the boat was gliding forward across the oily surface, fat ripples spreading away from its circular bow, the only sound a glutinous gurgle of ethane against the sides.

“That’s it,” Rosenberg said. “A back and forth motion; that’s fine. Remember the viscosity of the ethane is very low. Once you build up some momentum you should just sail on. Just like the air-bearing facility back in Building 9 at JSC, right? Don’t forget you have a back-up paddle in case you drop that one. Don’t try to reach in after it. And—”

“Let me row the damn boat, Rosenberg.”

He fell silent.

The shoreline receded, the ethane surface between her and solid land, growing into a thick black band.

Behind her, the lake’s far shore began to protrude over the horizon. It was a shallow, dome-shaped hill, blackened by gumbo streaks.

When she had judged she had got to a hundred yards out, she lifted her paddle out of the liquid and dropped it at her feet; her back and shoulders were aching, and she moved her arms around, trying to ease the muscles.

The boat continued to sail on over the surface of the oleaginous fluid. It was as smooth a ride, she thought, as if she was a beetle riding a hockey puck over damp ice.

At last she came to rest. The air seemed a little clearer here, in the middle of the lake, perhaps because of the constant dissolving and exsolving of gases from the ethane. It was as if she was embedded in some clear orange resin, with the dark grey methane clouds scattered over her head in their well-defined layer, like shadows on a ceiling.

From this far out she could make out more of the shape of the lake. It was obviously a horseshoe shape, curving around that central mountain — although from here, if she was honest, it was hard to tell if the lake was a true open horseshoe or if it closed over, around the far side of the mountain, into an annulus.

Looking back to shore was like looking across a sheet of blackened glass, to an encrustation of purple ice and foam at the lake’s rim. She could see Rosenberg standing patiently, stained with gumbo up to his waist, where the cable termination glittered. Seen from here, Rosenberg was very obviously alone on that primeval beach. His figure was the only vertical in a landscape of horizontals, starkly isolated. There was nobody else standing with him: no houses or buildings or cars behind him on that landscape of soft undulations, no trees, no birds in the sky. And in the frigid, mushy depths below her there was no life she could recognize, perhaps no life at all.

The boat rocked with a slow, soothing gentleness, with a period of maybe five or six seconds. The lake surface was almost a perfect black, its ripples heavy and shallow, free of breakers. Most organic solids, raining down from the atmosphere, would simply sink to the bottom of the lake. But here and there Benacerraf could see scatterings of foam, grey and purple. Some of that was spindrift, aerosols caused by bubbles bursting on the surface.

She felt her sense of place and time shift around her. It was as if the landscape of Titan was reaching her, through the isolating layers of her suit; she started to get a sense that she was truly here, alive and sentient, on this ethane lake, a billion miles from her birthplace. It took moments of stillness like this to understand this, she thought. Moments that the Apollo guys, Marcus White and the rest, were never given, in their hectic, task-crammed timelines. Moments that had come only, perhaps, in the quiet of their sleep periods, as those fragile Lunar Modules ticked and creaked around them. Moments, little fragments of true humanity, they were never encouraged to report. What a pity.