The instruments were laid out in a star-shape over an inert patch of the Moon, and connected by gold-coloured cabling to a central telemetry transmitter and a power plant — a thermoelectric nuclear generator, now long inert. Henry pointed out the sights like a tourist guide. Here was the seismometer, like a paint can on top of a silver drop cloth. This irregular ball in a squat box on legs must be the solar wind spectrometer. Three booms, spread out like the petals of a flower, made up the lunar surface magnetometer. And so on. All the instruments were boxes covered by gold-coloured insulation and white paint, covered with dust from long-gone astronaut footsteps, now blistered by years of sunlight.

There were packing brackets everywhere, dumped on the closely trodden ground.

When she turned away, she tripped on an ALSEP cable.

She didn’t even know it; Henry had to tell her. She couldn’t see her own feet as she walked, because of the chest-mounted control unit in her way, and she couldn’t even feel the cable through the inflated layers of her suit. The cable itself hadn’t unrolled properly. It seemed to have kept a kind of “memory” of being rolled, and once unrolled it wouldn’t lie flat, in one-sixth G.

Near the LM was much evidence of departure. The surface was littered by exhausted lithium hydroxide canisters and LM armrests, two abandoned backpacks, urine bags and food packs: garbage thrown out of the LM, the detritus of three brief days of exploration.

And the LM was surrounded by glittering fragments, for its foil insulation had been split and scattered by the blast of the departed ascent stage’s engine. There was a new ray system, streaks of dust which overlay the footprints.

On a rise three hundred feet away sat the Lunar Rover, with its camera blindly pointing to a sky into which its masters had disappeared.

Perhaps fifty yards from the LM, a US flag stood on its pole, held stiffly out on the windless Moon by a piece of wire. It had fluttered only once, as the brief blast of the LM’s ascent stage engine had rushed over it, and now it was tipped over, at an angle of thirty or forty degrees to the vertical.

Geena loped over to the flag.

She got hold of the staff, raised it straight, and tried to push it into the regolith. The staff would go in four or five inches easily, but then she came up against stiff resistance. Still, she managed to balance it, almost upright.

The relentless beating of sunlight had worn away at the fabric, and its colours — the red stripes, the blue star field — were no longer factory-bright. But the flag was the most colourful object on the Moon.

When she turned away from the flag, she saw a pattern in the dust. In the low sunlight she couldn’t make out what it was, and she walked around it.