He raised his head further. His ellipse of light lengthened, until the glow became too attenuated to make out. As far as he could see, across the width of the rille, and to left and right along its length, the Moonseed dust lay, shimmering in his torchlight. It looked as if a river of mercury had come lapping through the rille’s dusty walls.

He found a loose rock, a fist-sized pebble an arm’s-length away. On impulse, he picked it up. He looked at the big astronaut’s Rolex on his wrist, set its timer, and dropped the rock.

He watched the rock fall, at first with dreamy slowness, and then with greater, more Earth-like velocity as the slow gravity had time to work. If he got the timing right he would be able to calculate pretty accurately how far below him that surface was…

In the light of his torch, the rock hit the surface, and disappeared. The Moonseed dust closed over it without a ripple, as if it had never existed.

He checked his watch. Four seconds. The Moonseed was forty-two, forty-three feet below him.

He knew he had to wait for the results of his seismic analysis. But already he knew what he would find out.

The whole damn Moon was rotten with Moonseed, just as he’d suspected.

And yet the Moon was still here, unlike Venus.

He crawled to the back of the ledge. He worked his way along the ridge, setting out his instruments, little tin-can boxes containing sensitive seismometers, shrouded in thermal blankets. The seismometer signals would be analysed as real-time data and in terms of frequency to record the ground’s vibration. He set up combinations of theodolites and electronic distance meters that might give some clue as to the deformation of the ground, even here on the side of the rille. And he deployed, close to the rim of his ledge, a small cospec, a correlation spectrometer, that would be able to measure emission rates of any gases it could detect. The instruments would be connected to a central data collection and communications unit and batteries by multiplex cables, that he plugged into the backs of the boxes.

All these instruments were improvised from lightweight gear deployed by VDAP to gather real-time data on volcanic events. It was true that what he was investigating here was no volcano, but even volcanology was a young science; he hadn’t had any smarter ideas on what to bring here, to this infestation on the Moon.

He actually enjoyed setting up the science gear: plugging cables into their sockets, testing power couplings and data transmissions. It was simple work, no more complex than putting together a back-yard barbecue. Yet it was good for his soul to have some familiar tasks to get through, here amid all this strangeness. He moved between the instruments, the fans of his backpack whirring, the oxygen blowing cool over his face.