His monitors stayed stable. A glitch, then.

The incident was enough to brush him with fear.

Sobered, he went to work.

Side by side, carrying tools and equipment, they walked away from the Shoemaker, towards the Rover.

The Apollo Lunar Rover was a home-workshop beach buggy: about the size of a low-slung jeep, but with no body, or windshield, or engine.

“Oh, shit,” Henry said. “Have we really got to ride this thing?”

“Better than walking. You know what the Apollo guys called it?”

“Hit me.”

“Chitty Chitty Boeing Boeing.”

They bounced around the Rover, inspecting it.

The Rover was an aluminum frame, ten feet long, maybe six wide. It had four fat wheels — actually not quite wheels, but wire mesh tyres, with metal chevrons for tread. There were fenders, of orange fibreglass. There were two bucket seats with plastic webbing, and a minimal controller — just a gearshift-like hand controller between the seats, and a display console the size of a small TV. No steering wheel. At the back of the buggy there were bags for storage of equipment and samples.

The front of the thing was cluttered up with cameras and comms equipment. The TV camera still pointed at the sky, where it had followed the final departure of the astronauts in their LM ascent stage. The camera was coated in insulation foil, which had split and cracked. The umbrella-shaped high-gain antenna still pointed at Earth, where the Apollo astronauts had left it, for the Earth had not moved in all the years since.

This Rover was a working vehicle. He could see how the straps on the backs of the frame chairs were stretched and displaced from use. There were still dusty footprints on the foot rests fitted to the ribbed frame, and the mark of a hand, imprinted in lunar dust, on the TV camera’s insulation. And one fender at the rear had cracked, and had been crudely patched with silver wire and what looked like a checklist cover, though the text and graphic had long since faded. The Rover looked as if it had been used just yesterday, as if its original drivers would come back in a couple hours for a fourth or fifth EVA.

Tracks, crisply ribbed, snaked off back over the ground, diminishing into the distance.

The Rovers had been built from scratch by Boeing in just two years. There had only ever been four of these babies, and all of them had been flown to the Moon, and all of them had been left up here, in the clean airless sunlight. Two million bucks apiece.

At that it was a better fate, he thought, than to finish up in a glass case in the Smithsonian or some NASA museum, slowly corroding in Earth’s thick, murky air while generations of successively more baffled tourists came to stand and gawk…

He said, “What makes you think this old dune buggy is going to work anyhow? It was built to last three days, not thirty years.”

She shrugged. “It was built for temperature extremes and vacuum. What is there to go wrong? Neighbourhood kids stealing the tyres? They built better than they had to, in those days. Look at those old space probes from the 1970s. Pioneer 10 lasted twenty-five years… Anyhow, you better hope. Otherwise, it will be a long walk.”

Geena left the original batteries in place at the back of the vehicle, and set replacements on top of them. The new batteries were an advanced lithium-ion design. She started to hook them up with jump cables, and Henry loped around to help her. It was stiff, clumsy work; the Rover hadn’t been designed for this sort of maintenance, and Henry’s fingers were soon aching as he fought the stiffness of his gloves to manipulate leads and crocodile clips.

They bolted a lightweight TV camera to the Rover’s big, clunky 1970s original, and a new miniaturized comms package. The old antenna still seemed to be serviceable, however. Then they loaded Henry’s gear into the panniers in back of the Rover.

When Henry moved past the camera, a red light glared at him, steady and relentless. Back on Earth, they were already watching him.

Let them. For what they were going to do today, there had been time to prepare no checklists, no simulations, no training. Maybe for the first time in the history of US space exploration — the first since John Glenn anyhow — he and Geena were, truly, heading into the unknown. And there wasn’t a damn thing any of those anal retentive characters at Mission Control could do to help or hinder them, except keep quiet.

Happily, they seemed to know it.

Henry lowered his butt cautiously onto the right-hand of the two bucket seats, and swivelled his legs over the corrugated frame. The pressure in his suit made it starfish, and he had to use a little force to keep his arms by his side. He pulled restraints around his chest and waist.

Half-sitting, half-lying, he tried to relax.

The Rover was noticeably light; when Geena dropped into the left-hand driver’s seat, the whole vehicle bounced, and little sprays of dust scattered around the wheels.

She flicked switches on the console, and dials lit up.

“Left-hand drive,” Henry said.

“What?”

“If the first people on the Moon had been Scottish, you’d be sitting where I am.”

She lifted her gold visor to stare at him.

Then she dropped her visor, put her right hand on the joystick control, and jammed the control forward.

The wheels, each spun by an independent electric motor, dragged at the dust. The Rover bucked like an aluminum bronco, bounding out of its thirty-year parking spot, throwing Henry against his straps.

Following Apollo tracks as fresh as if they had been laid down yesterday, they headed east, towards the rille.

It was an exciting ride.

The turns were sharp. Every time Geena steered, all four wheels swivelled. The ground here was all bumps and hollows, an artillery field of craters, and every time they hit an obstacle one or two wheels would come looming off of the ground.

Henry, strapped to his lawn chair on top of this thing, was thrown around, especially when Geena took a swerve to avoid a rock or a crater.

“Holy shit,” he said.

“Don’t be a baby,” Geena said. “It’s only eight miles an hour. We’d be beaten by a San Francisco cable car.”

“Yeah, but how many hummocks per hour are we hitting?”

Geena pushed up the speed. The Rover bounced high off the ground, and threw up huge rooster tails of black dust behind them.

“Let me explain something to you,” she said as she drove. “Our consumables are being used up all the time.”

“Sure.”

“So at no point are we going to drive further than our walkback limit.”

“Which is the distance we can walk back to the shelter, with the oxygen in our backpacks. In case the Rover breaks down. I know. That makes sense to me.”

“Yes. But because our consumables go down steadily, that walkback limit gets tighter and tighter with time. And we are going to stay within that limit, all the time.”

“Sure,” Henry said.

“If that means we have to leave the rille before you’re ready, we do it. If it means we have to miss out on interesting-looking detours, we do it.”

“Geena—”

“And I’m going to be conservative, because the navigation computer on this thing doesn’t work any more. As far as walkback is concerned I’m the boss.”

He shrugged, a clumsy gesture in his suit. “Sure. You’re the boss.”

If she wanted to feel in control, if that was her way of avoiding the funk she suffered on the way in, it was fine by him.

…There were, Henry realized afresh, craters everywhere.

Some of the craters were subdued depressions, almost rimless, as if dug out of loose sand. They were easy to traverse; the Rover just rolled down a gentle slope. But others — mostly smaller — were sharper, with well-defined rims, the classic cup shapes of story books. The younger craters were full of rubble, like builders” slag, concentrations of angular blocks, and they had littered rims. Geena had to drive around those babies.