Agata pictured the scene as she’d left it, with mirrors angled into the cavity to bring in as much Esilian sunlight as possible. But even the safety lights in the cabin above would be off now, leaving Tarquinia to work with nothing but the view through the time-reversed camera. Exposing the bomb to ordinary light might trigger a tamper-prevention device, but it wouldn’t have made much sense to include the means to detect time-reversed light, when any act of sabotage had been expected to take place close to the Peerless, where the only source would have been distant starlight.

The camera could amplify the faint image obtained by a periscope inserted in each inspection hole, with sunlight introduced by a second mirrored tube. But so far, all Tarquinia had been able to report was that there were dozens of baffles inside the hollow beam, blocking the view along its length, leaving her with no way to proceed but trial and error.

Ramiro lay on the floor of the tent, one arm covering his faceplate; Azelio was crouched beside him, his head bowed in thought. They had spent eight days stripping as much as they could out of the Surveyor, preparing themselves for the grim contingency that an explosion might leave the hull damaged but not entirely beyond repair. Tools and medical supplies filled the tent; its three neighbours held the rebounder panels, parts of the cooling and navigation systems, and their entire stock of food. Agata understood now why there’d been so much dust around in the preceding days.

‘I’ve found it,’ Tarquinia announced calmly. ‘Six strides from the rim of the hull.’

Ramiro sat up. ‘What is there, exactly?’

‘About what you’d expect,’ Tarquinia replied. ‘A UV receiver on a board with a photonic processor. And a cable leading from the processor into the explosive.’ Agata felt sick. She could see the blue dust that had filled Medoro’s workshop; she could picture it spilling from the broken hull to mix with the Esilian soil.

‘No other components on the board?’ Ramiro pressed her.

Tarquinia said, ‘Remember when we shot up into a high orbit, to maintain contact with the probe? If that didn’t set this thing off, nothing will. There’s no accelerometer here.’

‘Is the beam warm?’ Ramiro asked.

Tarquinia buzzed curtly. ‘Yes! I just drilled a hole in it.’

‘You should leave it for a chime and see if it cools down completely,’ Ramiro pleaded. Agata understood his logic: a passive system that needed an external signal to wake it would not be generating heat, but the kind of photonics required to detect an incision in the cable would have to be constantly active.

‘If it gave out a heat signature, that would defeat the whole point of trying to hide it,’ Tarquinia replied.

Ramiro said, ‘I think they would have imagined the cooling system still running while we were doing this.’

‘All right,’ Tarquinia agreed reluctantly. ‘I’ll wait.’