In the first second — the first one or two rattled heartbeats — he only fell through a couple of feet. He fell stiffly, his suit starfishing around him, as if he was in some body-shaped coffin.

Two seconds, and, picking up speed inexorably, he had fallen ten feet. The rope was coiling behind him, still fixed to his waist. How much was there left? Enough to stop him hitting the Moonseed river?

Would he just drag his anchor rock off the lip of the rille after him?

Three seconds, maybe twenty feet, and at last his speed was becoming respectable. No air here, so no terminal velocity; if there was a hole all the way to the centre of the Moon you would just keep on falling, accelerating steadily, until—

His feet hit the surface of the Moonseed river.

It worked its way up his legs, to his waist, sluggish ripples spreading out from him. His speed slowed rapidly as the resistance of the dust built up. He could feel the pressure of the dust on his legs, crumpling the inflated pressure suit.

Now he was sinking slowly, as if into treacle. He tried to keep his arms out.

Up to his waist. He couldn’t move his legs.

He would presumably reach some level at which he would be buoyant. The dust was all but a fluid; Archimedes” principle would work, even here. How deep would that be? So deep that the pressure of the dust would crack his visor, ramming itself into his mouth and nose and eyes? Or maybe the end would be less spectacular: eventually, the heat trapped by the dust would surely kill him… The dust was up to his chest now. But his rate of descent was slowing. He tried to kick at the dust; maybe if he could lie on his back he could float like a swimmer on the Dead Sea. But he couldn’t move his legs, not so much as an inch; it was as if his pressure suit was embedded in concrete.

But the rope was taut, pulling at his waist. Geena. She was trying to drag him out of here.

He lifted his hands, and grabbed at the rope which snaked out from his waist like an umbilical cord. He could feel the tension; he imagined Geena at the surface, hauling, digging her feet into the regolith.

It was working. He could feel the dust falling away from his legs. Maybe he was out of it already.

He kept pulling, and Geena kept hauling, and he could feel himself rise with dreamy grace. Maybe he was going to live through this after all…

But now he became aware of a new problem. He couldn’t hear the pumps and fans of his backpack any more, nor feel the breath of oxygen over his face.

When he looked down at his chest panel, there was nothing but red lights. The heat, the pressure of the dust had killed it.