She found she had reached the flitter. She was so cold she wasn’t even shivering any more. It was almost comfortable.

She couldn’t lie on the ground. But she found a way to use bits of debris from the flitter, stuck in the ice, to prop herself up without having to lean on anything. After a time it seemed easier to leave her eyes closed.

‘Your body is losing its ability to reheat itself. You must find an external source of heat. You will soon drift into unconsciousness . . .’

‘I’m in my eighth cadre,’ Minda whispered. ‘You have to move cadres every two years, you know. But I was chosen for my new cadre. I had to pass tests. My best friend is called Janu. She couldn’t come with me. She’s still on Earth . . .’ She smiled, thinking of Janu.

She felt herself tilting. She forced open her eyes, frost crackling on her eyelashes. She saw that the pretty, silvered landscape was tipping up around her. She was falling over. It didn’t seem to matter any more; at least she could let her sore muscles relax.

Somewhere a voice called her: ‘Always protect your core heat. It is the most important thing you possess. Remember . . .’

There was something wrong with the silver ghost, she saw, through sparkling frost crystals.

The ghost had come apart. Its silvery hide had unpeeled and removed itself like a semi-sentient overcoat. The hide fell gracelessly to the frozen ground and slithered towards her.

She shrank back, repelled.

What was left of the ghost was a mass of what looked like organs and digestive tracts, crimson and purple, pulsing and writhing, already shrivelling back, darkening. And they revealed something at the centre: almost like a human body, she thought, slick with pale pink fluid, and curled over like a foetus. But it, too, was rapidly freezing.

All around the subsiding sub-organisms, the frozen air of Snowball briefly evaporated, evoking billowing mist. And the dormant creatures of the Snowball enjoyed explosive growth: not just lichen-like scrapings and isolated flowers now, but a kind of miniature forest, trees pushing out of the ice and frosted air, straining for a black sky. Minda saw roots tangle as they dug into crevices in the ice, seeking the warmth of deeper levels, perhaps even liquid water.

But in no more than a few seconds it was over. The heat the ghost had hoarded for an unknown lifetime was lost to the uncaring stars, and the small native forest was freezing in place for another millennium of dormancy. Then the air frosted out once more.

At last Minda fell.

But there was something beneath her now, a smooth, dark sheet that would keep her from the ice. She collapsed onto it helplessly. A thick, stiff blanket stretched over her, shutting out the starry sky.

She wasn’t warm, but she wasn’t getting any colder. She smiled and closed her eyes.