The occulters were approaching the bottom of the mountain. Having them crawl over the sharp edge that divided the slopes from the base would have been insanely ambitious, so the machines had been instructed to fly from one surface to the other, keeping as low as possible but sparing themselves the most difficult terrain.

Centrifugal gravity turned the base of the mountain into a sheer vertical wall. The cargo hooked to the occulters’ arms would hang down over them, applying a torque that would try to peel them off the rock, and increasing the risk of the connecting strings becoming tangled in the clockwork. Ramiro had programmed adjustments to the depth and angle of the drills that he hoped would minimise the problems, but it was all untested; there’d been no reason back on the Surveyor to rehearse for this strange asymmetric loading. He found it hard not to resent Giacomo’s group for failing to devise a better solution when they’d had three years’ warning, but then the innovation block wasn’t an imaginary disease that people invoked just to excuse their laziness. Agata’s long silence since she’d set out to overcome it proved just how pernicious it must be.

A short burst of data appeared on the console. Tarquinia chirped. ‘Number one’s made the jump!’

Ramiro waited for the next report, then scrutinised the figures. ‘It’s clinging on, and it hasn’t jammed.’ He wasn’t satisfied yet; it was still possible that the strings would become progressively twisted. The occulter rotated its body in opposite directions with each step, so all things being equal it ought to unwind as much it entwined, but he could imagine some configurations of the strings interfering with the process and favouring one direction.

But in the third report the torques were unchanged, and the fourth confirmed that nothing was escalating. The occulter was cycling its way up the rock face towards its target, tenaciously regaining the same equilibrium with every step.

Ramiro sagged across the desk. ‘I think I just aged another six years.’

Tarquinia said, ‘Better here than back on the Surveyor.’

‘That’s true.’ Ramiro had never thanked her for the lengths to which she’d gone to spare him that fate. He sat and watched her for a moment, wondering what she’d say if he raised it after all this time. But he suspected that it would only annoy and embarrass her if he told her that he knew what she’d done for him.