So the cycles of air, water and solids would have to be maintained with something close to a hundred per cent efficiency. The sealing of the Ship against leakages was vital, and so nano-machines laboured to knit together the hull. The control of trace contaminants and pests would have to be ferociously tight: more swarms of nano-bots were sent scurrying in pursuit of flakes of hair and skin.

Not only that, the Ship’s design had been hastily thrown together, and the vessel wasn’t even completed on launch. The construction had been a hurried project anyhow, and the shaving-off of those final ten or twelve days of preparation time, as the Coalition fleet sneaked up in the dark, had made a significant difference. So the crew laboured to complete the ship’s systems in flight.

The most significant difficulty, Rusel believed, was the sudden upping of the design targets. A thousand-year cruise, the nominal design envelope, was one thing. Now it was estimated that, cruising at about half lightspeed, it would take Ship Three fifty times as long to reach Canis Major. Even relativistic time dilation would only make a difference of a few per cent to the subjective duration. As a consequence the tolerances on the Ship’s systems were tightened by orders of magnitude.

There was yet another goal in all this rebuilding. A key lesson of ecosynthesis was that the smaller the biosphere, the more conscious control it would require. The Ship was a much smaller environment than a Port Sol habitat, and that presented problems of stability; the ecological system was poorly buffered and would always be prone to collapse. It was clear that this small, tight biosphere would always have to be consciously managed if it were to survive.

That was manageable as long as the first crew, educated on Port Sol, were in command. But to ensure this in the long term the Ship’s essential systems were to be simplified and automated as far as possible, to reduce the skill level required to maintain them. They couldn’t foresee all that might befall the Ship, and so they were trying to ‘future-proof’ the project, in Andres’s jargon: to reduce the crew to the status of non-productive payload.

As Diluc put it with grim humour, ‘We can’t allow civilisation to fall in here.’

Despite the horror of Port Sol, the hard work, and the daunting timescale Andres had set - which Rusel suspected nobody believed anyhow - the rhythms of human life continued.