But he had.

Nevertheless, he had proven himself to be one of the masters of the proteus, Keanu’s 3-D printing and fabrication system . . . the nearly magic Architect technology that allowed humans to (a) get rid of the Reivers, (b) make supplies and equipment, and, ultimately, (c) turn themselves into the galaxy’s smallest spacefaring civilization. If anyone could take credit for the design, construction, and operation of Adventure, it was Sanjay.

“Entry interface,” Sanjay said.

Adventure began bumping at just that moment, much like an airplane hitting turbulence. As her mother, Megan, had reached for her hand during flights across the Rockies and into Houston on horrible stormy afternoons, Rachel reached for her daughter’s.

She had faith in Adventure . . . as much faith as anyone could place in a machine that was several thousand years old and built by a race of sentient aquatics on a world far, far away.

It was, when she looked back, a crazy challenge—outfitting an ancient spaceship preserved in vacuum for centuries. How do you do that?

Well, first you turn the work over to two dozen former Indian Space Research Organization (ISRO) spaceflight engineers. Given the proteus tools available to use in the Keanu system, the largest challenge was . . . theological. That is, technical challenges turned out to have possible solutions, all of them workable, in theory.

What kind of propulsion system should the Sentry vessel have? Thermal protection? Environmental?

Should it spin or tumble to provide artificial gravity?

The development took six years, once Rachel and the others realized they were truly headed back toward Earth and would inevitably have to land there. Some of them, anyway. (And as the anointed ruler of the HBs, a job she kept trying to shed, Rachel knew it would have to be her.)

First, the HBs had tried to create an indigenous lander. After all, they were already using proteus printing to fabricate engines, control systems, environmental systems, seats, and everything else . . . why not the actual shell or, as Sanjay and former astronaut Harley Drake kept telling her, “The bus, Rachel. It’s called a bus.”

Their first “bus” was a stubby, short-winged thing like one NASA had tried to build around the year 1995. It was called the X-38, Rachel thought—she remembered her father, Zachary, talking about it. It never flew as more than a prototype, but it was the model they used.

And during its first launch from the surface of Keanu—launch being an extreme word for a process that essentially involved squirting some reaction mass downward, causing the X-38 to float off the surface—the vehicle failed. Some defect in their design or manufacture caused the X-38 to break up when its main engine fired to put it in a big looping test orbit.

Two HBs died, including Shane Weldon, one of the original space professionals from NASA who’d run Zack’s mission to Keanu.

So, with time running out, and no wish to come up with a new design and risk another failure, Rachel and Sanjay and company turned to the Sentry ship that had been parked on the surface of Keanu.

The Sentry ship was a needle-nosed, stubby-winged thing that looked like a tapered artillery round. Over the centuries it had been stripped and looted like a pharaoh’s tomb; when humans first discovered it, it was literally just a shell.

But what a shell! Sanjay and his team were amazed at the structural integrity of the Sentry ship the first time they pumped air into it. “The leak rate is better than Brahma!” Brahma had been the Coalition craft commanded by Pav’s father, the one that landed on Keanu back in 2019 a few hours after Zach Stewart’s Venture spacecraft.

Once the HB team proved that the Sentry ship would hold air, it was time to equip it with propulsion systems and fuel tanks (all of it, every molecule, arranged and/or manufactured in the human habitat) and items like storage lockers for food and cargo, and seats (human-sized, except for one) and controls and . . . well, a shitload of equipment. Since the cockpit was designed for Sentries, who were generally a half meter taller than humans, five of the seats wound up having to be suspended in the middle of the volume, “like flies in a spiderweb,” in Sasha Blaine’s unhelpful words.

One other major task was coating the exterior of the Sentry ship with a thermal protection system. Sanjay’s rudimentary analysis showed that the “metal” of the Sentry shell was unknown. Obviously, as Harley said, “given that it’s lasted ten thousand years, it must be pretty fucking robust.” But they had no way of knowing how it would withstand the thousand-degree temperatures of reentry into Earth’s atmosphere.

So they elected to coat the entire exterior in the same material used for the X-38 . . . a light silica-based compound that had been evolved from the space shuttle by Brahma’s engineers. The extra layering spoiled the Sentry ship’s clean, classic lines . . . but everyone felt safer knowing that they had protection during reentry.

This work took years. In fact, when Adventure finally launched four days ago, Rachel was still not sure they had done everything possible, run every test.

They had, however, taken time to do one old-fashioned thing: They had given the Sentry ship a name, Adventure, partly to honor the original Venture that brought Rachel’s father’s crew to Keanu . . . but mostly to remind them of their new mission.

But they had simply run out of time. Keanu was approaching Earth, where it would be a fat target for Reiver weapons. Jaidev, Harley, and all the HB leadership had agreed: Adventure had to reach Earth at the first opportunity.

Now here they were, passing the Antarctic, dropping lower and lower, over the empty expanse of the Indian Ocean. To their right, roughly northeast, they could see a huge cloud formation. “Cyclone,” Pav said. “Bad news for Indonesia.”

“Is it still called Indonesia?” Xavier said.

A new voice sounded inside the cockpit. “Adventure, this is Bangalore Control—” Rachel sat up at those words, since she remembered hearing them from Brahma mission director Vikram Nayar back during that horrible week of the Venture/Brahma landings, the deaths, the mess that led to her arrival on Keanu.

Rachel and the HBs had been in touch with Earth for thirty months, of course. Carefully. The HBs suspected that the Reivers had reached their home world as many as nineteen years in the past, once they’d been expelled from Keanu. But they had no information about the success of their invasion, the extent of the infection. Well, there had been stray, strange transmissions warning Keanu and the HBs to . . . stay away.

As if they would. As if they could.

There had also been odd, plaintive transmissions from India and the United States, people asking for information on loved ones lost twenty years ago. Sasha Blaine began to build a database, but it was already heartbreaking: They knew that a handful of names were not among the HBs, meaning they had gone missing—or died—on Earth in 2019.

“Bangalore, Adventure. At forty-five thousand meters, descending. Are you tracking?” Pav was handling the communications, for obvious reasons. He was human; he was from India; and he had been Keanu’s only voice link with Earth so far.

“We are tracking you,” Bangalore said.

Pav glanced over his shoulder at Rachel. “So they can still do that much.”

Their imaging systems and signal intercepts had led the HBs to believe that humans had given up spaceflight. They had detected no air-to-ground transmissions (an obsolete phrase, but still the best they could do) from lunar bases or Mars orbiters. They weren’t even sure there were still space stations.

What popular or historical material they had managed to screen confirmed this: The last two space missions in the history of human spaceflight had been to Keanu in 2019.