The break in the clouds lasted several days. It had been years since the sky had permitted more than a glimpse beyond the atmosphere, and now a freak high-pressure system had unfolded the velvet night like a gift. The astronomer would have taken advantage, but he was miles from any observatory, and he knew the constellations by heart. He would have gained nothing from retracing his charts, aside from the small comfort of a familiar tableau. He had learned to live without such respite.

He no longer dwelt on the uncertain future. The centuries had taught him that.

He knew that one day everything would come together. Somewhere on Earth, the rest of his crew still lived. Their paths rarely crossed, but in his travels the astronomer knew that there was hope, as long as they all kept moving.

Every decade or so he would return to the hangar, following secret paths hidden in forbidding places. Earth was cool beneath her surface, the rust still fresh. Miles underground, he would check up on the ship, activating repair systems if necessary, fixing things himself when the occasion arose. Sometimes it would take months, shirtless under ancient worklights, his body feeling a fraction of its age; the slow work of rebuilding an engine the size of a house, or resealing an airlock that could fit a small asteroid. Physical labor focused his mind.

He would go to the command center and perform a pre-launch check, going over every last system to be sure that the enormous machine was ready. In his heart he lamented the fact that they’d only had time to build one before the world stopped. Before the sculptor died.

Often he would find letters on the main console, left for him by the others when they made their visits in the intervening years. Sometimes it would be a terse checklist from the pilot, scrawled in his hasty script, probably in the midst of some subterranean debauchery (the astronomer shook his head and laughed at these). Other times words of encouragement from the engineer, or repair notes from various crewmen.

But above all he cherished the letters from the physicist. He would fold them and keep them in his breast pocket until they disintegrated. He left replies for her, and always he would return to find her precise handwriting in place of his own.

They had all agreed to travel apart, to keep their knowledge safe from the cannibals and luddites, but he longed for her. Her presence was as real as it had been centuries before, when the future was bright and nothing lay between them save a table and a set of blueprints.

He no longer dwelt on the uncertain future. But still he felt the touch of her lips upon his own.