Ramiro was unrepentant. ‘If you’re going to take offence every time I nag you about something that could get us killed—’

‘All right!’ Tarquinia’s expression softened. ‘I’m all in favour of some mutual irritation anyway. Better than falling asleep on the job.’

‘Don’t tempt me with that.’

‘Ready,’ she said. It wasn’t a question. She threw a switch on her panel and the gnat fell away from the mountain.

Ramiro’s queasiness at the sudden loss of weight soon changed to elation. He’d forgotten how beautiful the outside could be; after six years of moss-light and display screens, the muted shades of starlit rock spreading out above him felt like liberation. As the mountain retreated, he looked down to the bright line of jumbled colours that divided the sky. To his right, the long trails of the home cluster’s stars reached their greatest luminance along this border, then vanished completely. To see any further would have meant seeing these stars’ futures – and they weren’t sending light backwards in time against their own thermodynamic arrows. To his left, the orthogonal cluster had the sky to itself, sprinkling its domain with small, neat colour trails.

‘Firing engines,’ Tarquinia warned.

Ramiro was thrust abruptly back against the couch, ridding him of any notion that he was standing. He’d been expecting the change of vertical, but the pressure on his body was distinctly more uncomfortable than he remembered. After a few pauses wondering whether he was going to be able to hold down his last few meals, he managed to ossify parts of his torso, giving it better support against the unaccustomed weight so that it no longer threatened to squeeze out the contents of his digestive tract.

As the gnat sped away from the mountain, the sky’s stark asymmetry made it easy to maintain a sense of direction, but Ramiro still needed to check the navigation console to gauge their progress. When he finally looked back towards the Peerless again it was a pale grey triangle, a dwindling near-silhouette against the star trails. The engines labouring to end its spin produced no visible trace at all; even if the sparse dust rising out from the slopes was scattering the beams a little, they were far into the ultraviolet.

‘It should take about three and a half bells to reach the Station,’ Tarquinia predicted.

Ramiro said, ‘Isn’t it usually six?’ No wonder he felt so much heavier than on his last flight.

‘This gnat was designed for towing cargo,’ Tarquinia explained. ‘I flew it myself, the last time they upgraded the Station. I was carrying a whole prefabricated living unit, but coming back, with no external load—’ She brought six gloved fingertips together, then flung her hand forward as she spread them.

Ramiro didn’t want to risk insulting her again, so he fought back the urge to ask her exactly how much cooling air they’d brought. Carla’s glorious optical rebounders required no fuel, with the gnat’s gain in kinetic energy coming solely from the creation of light, but the frequency-shifting mirrors that enabled that trick still generated waste heat. The more powerful the engines, the more air it took to carry heat away into the void.