‘Yes.’

She was very tired. She didn’t seem to be hungry, or thirsty. She wondered how long it was since she had eaten. She stared at the frozen air around her, trying to remember why she had come here. An idea sparked, fitfully.

She got to her knees. She could feel the diamond grid of the suit’s heating elements press into the flesh of her legs. She swept aside the loose snow, but beneath there was only a floor of hard water ice.

‘There’s nothing here,’ she said dully.

‘Of course not,’ the ghost said gently. ‘The tides washed it all away.’

She began to pull together armfuls of loose snow. Much of it melted and evaporated, but slowly she made a mound of it in the centre of the room.

‘What are you doing?’

‘Maybe I can breathe this stuff.’ She knew little about the flitter’s systems. Maybe there was some hopper into which she could cram this frozen air.

But the ghost was talking to her again, its voice gentle but persistent, unwelcome. ‘Your body is continuing to manage the crisis. Carbohydrates which would normally feed your brain are now being burnt to generate more heat. Your brain, starved, is slowing down; your coordination is poor. Your judgement is unreliable.’

‘I don’t care,’ she growled, scraping at the frozen air.

‘Your plan is not likely to succeed. Your biology requires oxygen. But the bulk of this snow is nitrogen. And there are trace compounds which may be toxic to you. Does your craft contain filtering systems which—’

Minda drove her suited arm through the pile of air, scattering it in a cloud of vapour. ‘Shut up. Shut up.’

She walked back to the flitter. By now it felt as if she was floating, like a ghost herself.

The silver ghost told her about the world it came from. It was like Snowball, and yet it was not.

The ghosts’ world was once Earth-like, if smaller than Earth: blue skies, a yellow sun. But even as the ghosts climbed to awareness their sun evaporated, killed by a companion pulsar. It was a slower process than the doom of Snowball, but no less lethal. The oceans froze and life huddled inward; there was frantic evolutionary pressure to find ways to keep warm.

Then the atmosphere started snowing.

The ghosts had gathered their fellow creatures around them and formed themselves into compact, silvered spheres, each body barely begrudging an erg to the cold outside. Finally clouds of mirrored life forms rolled upwards. The treacherous sky was locked out - but every stray wisp of the planet’s internal heat was trapped.

Minda wondered if this was true, or just some kind of creation myth. But the murmuring words were comforting.

‘My home Conurbation is near a ruined city. A bit like this one. The ruin is an old pre-Occupation city. It was called Pah-reess. Did you know that?’

‘No. It must be a wonderful place.’