“There isn’t. But there is ice at the Poles. Deep in the dark, where the sun never shines.”

“Really? A lot of ice?”

Her father hesitated. “Well, some people think so.”

“Anyhow,” she said, “I don’t want to be a farmer.”

Her father stared up at the Moon. “You know, you’re special. I wrote your name up there, in the dust, and it will be there for a million years.”

“You told me, Dad.”

“Yeah.”

A cloud passed over the Moon’s face. It got colder.

They went indoors to watch TV.

One day, human scientists would call it the Impactor.

It had about the mass of Mars, a tenth of Earth’s. Humans would later speculate that it was a young planet in its own right.

But they were wrong. It was not a planet.

The object barrelled through the dusty plane of the Solar System.

But there seemed to be something in the way.

…And on the Moon, the Rover had jolted across the bright dust, climbing gentle slopes under the black sky, bathed in the sun’s flat light.

It must have looked strange, Jays thought, if there had been anyone around to see it. The Rover looked like a beach buggy from somebody’s home workshop. And yet here were the two of them in their shining white pressure suits, like two dough boys riding a construction-kit car, bouncing across the Moon itself. They rose up a slight incline.

Suddenly there was the rille: Schröter’s Valley, a gap in the landscape in front of them. It wound into the distance, its walls curving smoothly through shadows and sunlight. Jays could see boulders that must have been the size of apartment blocks, strewn over its floor.

Jays tried to keep the excitement out of his voice. “Look at that old rille. I’m sure I can see layering in the far side. Look, Tom. Over at one o’clock.”

Tom, distracted by the driving, said, “Let’s get up there before we do any geology.”

The Rover jolted to a stop.

Jays released his seat belt, and let it snap back into its frame. He tried to stand up. But the slope was deceptive; it was an effort to haul his suited frame out of the Rover’s lawn seat.

He took a step away from the Rover.

His suit was a stiff bubble around him, shutting out the Moon. He could hear the whir of pumps and fans in his backpack, feel the reassuring breath of oxygen over his face. The sunlight caught scuffs and scratches in his gold-tinted sun visor, creating star-bursts.