‘I’d have no objection to that,’ Tarquinia said. ‘But once we dock, whatever happens to the Surveyor will be out of my hands.’ Ramiro had a brief fantasy of the Surveyor orbiting the mountain at a safe remove while evacuees jetted across the void to join them – but unless they were lugging six years’ worth of food there wouldn’t be much point. And even then it could only end badly, once the lucky few had to start turning the rest away.

Azelio’s expression changed abruptly. He buzzed with a kind of pained relief, as if he’d just decided that his fears were not only groundless but embarrassingly naïve. ‘Whatever else we’re missing,’ he said, ‘we know the Peerless’s location when the disruption takes place. If we were going to be hit by something, we could avoid that just by changing course: we wouldn’t happily steer straight for the meteor.’

Ramiro said, ‘Maybe they will change course. Maybe they already did. Either way, the disruption still happens.’

‘Exactly!’ Azelio replied. ‘So it can’t be down to a collision. If changing the location were enough to stop it happening . . . it couldn’t happen. On Esilio, we were never forced to do anything against our will, so how could a mountain full of people with no intention of dying be forced to choose a fatal trajectory? Stumbling blindly into a collision would be one thing – but how could it happen with foreknowledge?’

Agata considered this. ‘I think your argument would hold if we knew the cause with certainty. But it’s not so clear-cut when we’re less informed – when we’re not sure that the disruption will be fatal, and we’re not sure that it involves a collision at all.’

Azelio scowled. ‘So because we can’t know that it’s a collision . . . it’s more likely that it is?’

‘Is that really so strange?’ Agata replied. ‘If everyone on the Peerless was confronted with the certain knowledge that the course they were on was suicidal, then there’s no way they’d persist with it – unless some freakishly unlikely set of events undermined the efficacy of their intentions. With three years’ warning to achieve the necessary swerve, what could possibly stop them? The engines would need to drop off, and every last person capable of improvising any kind of substitute would need to die of some convenient affliction. I don’t believe for a moment that the cosmos contains anything so unlikely.

‘But taking an unknown risk is different. If we don’t know exactly what would make us safe, there’s no need for an endless barrage of misfortune to keep us from finding the right solution.’