For years NASA had been in the stupid habit of bestowing individual names on pieces of equipment. The agency had even held a goddamn contest to name the rover that would be used on the third lunar landing, and “Buzz” had been the winner . . . after the second man to step on its surface.

Well, wherever he was, Buzz Aldrin was laughing, because while rovers Neil and Gene had been relegated to traverses on the nasty, asbestoslike lunar soil, rover Buzz was the first on an entirely new world.

Or starship. Let’s not forget that.

The Venture lander stood eighteen meters high and, with the low sun angle, cast a shadow three times that long. In that shadow, Zack pulled the lanyard that opened an entire fifth of Venture’s landing stage . . . Buzz slid out, tilted, then began to unfold itself.

During training on Earth, the deployment process had been fairly noisy, reminding Pogo of the rattling grind of an old roller coaster pulling its cars to the top of the loop.

But here, in the snowy vacuum, there was no noise. With a strange sort of majesty, Buzz’s wheels dropped into place, the cabin inflated to its full size, and the gold Mylar antenna unfurled. In no more than a hundred and twenty seconds, the spidery vehicle was ready for action. “It looks bigger here,” Pogo said. In the bays at Huntsville, surrounded by various models of lander and rover mockups, Buzz had looked a little sad and puny. Not on Keanu, though.

“Big enough.” Zack seemed distracted, which was understandable. Already tasked with a challenging spaceflight, he had watched his mission transformed into something out of legend: the first exploration of an alien artifact.

How could anyone prepare for that?

Pogo joined him in transferring additional equipment from the Venture lockers to Buzz’s frame: additional oxygen tanks, the scientific package, new cameras, cabling. The work progressed in stops and starts. One tank simply would not come out of the bay. “It’s like it fucking grew!” Pogo snapped, only dimly aware that he had just cursed on an open communications link.

Here he saw Zack Stewart in all his stoic glory. Without a word he jumped ahead on the unstow checklist and opened the adjoining bay, patiently handing the gear stored there to Pogo until it was empty.

Then he took a screwdriver and poked a hole in the adjoining wall. He used a pliers to peel open the leaves of the wall. “Is that a good idea?” Pogo hadn’t considered such a maneuver. It reminded him too much of working in his home garage. . . .

“This isn’t a load-bearing piece,” Zack answered, going back to the screwdriver, which he jammed into the opening to free the jammed tank. “Besides, when we leave, this all stays behind.”

Pogo couldn’t decide which was more surprising, the fact that the tank was freed in this manner or that those were the only words Zack Stewart uttered in half an hour.

Buzz had a bubblelike pressurized cabin large enough to hold four astronauts packed so closely they might have to take turns breathing. With two, it approached comfort. For now, however, there was no need for Zack or Patrick to depressurize the cabin: Buzz could be driven from outside, too. (It was a battery-powered electric vehicle not much more complicated than a golf cart.)

Or, as Zack quickly demonstrated, it could be pushed and pulled on the snow toward Vesuvius.

Within minutes, the two were standing at crater’s edge. “How are you holding up, chief?” Pogo asked. He was concerned about Zack’s silence during the work with Buzz.

“Just scouting the terrain. Check it out.” Zack picked up a chunk of ice and launched it into the vent. “Can’t just drop it . . . it might take ten minutes to hit.”

From this distance, Vesuvius Vent reminded Pogo of Meteor Crater in Arizona, a substantial hole in the ground at least a click across and almost a couple of hundred meters deep. He had visited it for lunar geology training. But the Arizona crater was rocky while Vesuvius Vent was largely whitish, covered with impossibly ancient ice and snow, except where the heat of the venting had exposed the surface.

Zack began “giving the suite,” doing a geological survey of the scene. “If that eruption had been volcanic, those bare spots would be black.”

“It would have rolled some of these boulders, too,” Patrick said. He was damned if he’d let Zack dominate the survey. Why waste five hundred hours of geological training?

“So it really wasn’t an eruption, just a venting. Steam.”

“Heat down below.”

“Some deposits and layering.”

“A long time ago, though.”

As they spoke, Zack and Pogo crab-walked their way along the rim, away from Venture and Brahma. “Too bad the floor is shadowed,” Zack said.

“If it is a floor, and not a bottomless pit.”

“If it’s a pit, it can only be a hundred kilometers deep.”

Pogo saw something below, and stopped so suddenly he almost lost his footing. He raised his sun visor to be sure. “Zack,” he said, “take a look.”

Zack joined him, both men looking down into the shadowy depths. “Venture,” Zack said, “are you getting imagery?”

“Not with you jiggling around,” Tea said. Helmet cams were great tools, but had the disadvantage of reacting to every twitch and jolt an astronaut made.

“Okay, we’ll try,” Zack said. “Call this anomaly one.”

“We can’t make it out—”

“It looks like a ramp,” Patrick said. “Directly at one o’clock, one third of the way up from the floor.” Indeed, from this angle he and Zack could see the vent floor . . . a relatively smooth, snowy surface . . . and what could only be a ramp hewn out of the vent wall.

“I make it ten meters wide,” Zack said. “But that’s only a guess.”

“It looks wide enough to drive a rover down.”

“Greetings!” From their voices on the radio, Pogo had heard Lucas and Natalia approaching. Now they appeared, Lucas literally towing a pile of equipment and supplies on a sled! “Cool! Somebody back in Bangalore was thinking ahead,” Pogo told them.

“This looks like a Russian innovation to me,” Zack said.

Now there were four spacewalkers gathered at the rim. Zack pointed out the ramp. Patrick heard Natalia gasp. “Amazing . . .” she said.

Lucas sighed. “Too bad it doesn’t reach to the top.”

“It’s a long way away,” Zack said. “We’d have to drive a couple of hours just to get to the other side.”

Which reminded Pogo: “What are we doing with Buzz, anyway? There’s no easy way down to the bottom of this thing.”

Zack turned in his cumbersome suit, his gold sun visor raised . . . Pogo could see him smiling. “Everybody grab one wheel.”

Without understanding, Pogo simply followed orders, reaching for the rover. “Now what?” he said.

“Lift,” Zack ordered. Buzz weighed three hundred kilograms on Earth; on Keanu it could have been raised by a single human. It was only the sheer size of the rover that made it helpful to use four pairs of hands. “Now,” Zack said, “to the rim. Right there, the steep spot . . .”

Only then did Pogo realize that Zack planned to literally throw Buzz the rover off the rim. “On my mark,” Zack said.

Pogo wasn’t the only doubter. “Zack, are you sure about this?” Natalia asked.

“Yes. We need to explore Vesuvius, and the rover has the tools. No more questions. One, two, three—!”

Propelled perhaps three meters laterally, off the rim of the vent, Buzz floated down, down, down, kicking off one outcropping and starting a slow tumble, but still remained upright. The astronauts could see the rover bounce twice, then, just like Venture during its landing, settle onto the snow and ice.

“I don’t fucking believe it,” Pogo said.