Excerpt

To minimize its time in Jupiter's radiation belt, the Sargent Shriver decelerated so hard that many of its passengers grayed out. Magsails folding, the ship roosted on the icy plain of Neith Spaceport, on Ganymede's leading hemisphere.

Elfrida Goto regained consciousness on the floor of the senior trainees' bathroom; she had ignored the warnings to strap in. She met the eyes of Jennifer Colden, whose idea it had been to get rid of their stash by injecting it all at once.

"Urrrggh," Elfrida said.

Out on the radiation-soaked ice, four rovers rolled between the parked spaceships. They looked like crude ice sculptures on treads. Banners unfurled between them:

WELCOME SPACE CORPS!

GANYMEDE CONGRATULATES THE GRADUATING CLASS OF 2277!!

Colden rolled onto her side and threw up.

A housekeeping bot trudged across the galley floor and vacuumed up the puke. Elfrida noticed that up was up, and down, down again.

"Am I ever ready for some R&R," Colden groaned.

"Um, Colden? Like we've done anything else since we left Earth?"

"That lovejuice was crap. I don't feel loved-up. I feel sick."

"We took too much," said Elfrida. She grabbed the wet wipe dispenser to pull herself upright. Figures sleeted across her woozy brain. Ganymede's gravity was 17% of Earth's. Diameter 5,268 km. Biggest moon in the solar system. Its day lasted just over a week. The 3D mirror framed her reflection: cotton-candy-pink hair, filed incisors, a Las Nerditas tattoo on her cheek.

"Remind me never to score drugs on Ceres again," Colden said. "Groan."

The class of 2277 gathered in the ship's boarding lounge, where the dean reminded them that they would be expected to uphold the high ethical standards of the Space Corps during their stay on Ganymede.

"While this is a graduation trip, a treat for all you wretched yoof, remember that you have not yet received your assignments."

At this point Elfrida and Colden flew into the lounge, uniforms rumpled, gear trailing from their hastily packed rucksacks. Mocking texts piled into the HUD area of Elfrida's network interface contacts. Half-blinded, she stumbled against Magnus Kristiansen, the trainee who ranked top on every test they were given.

"It's a miracle you two even graduated," Kristiansen texted her, pushing her upright so her boots could grip onto the floor.

"Well, we did," Elfrida texted back, not very cleverly.

"It's not over yet. They won't say so, but this is our final exam. Flunk it, and you'll probably get assigned to Ceres."

Elfrida knew he was right. The Space Corps could be sneaky like that. But after two years of training, she had a pretty good handle on what was expected, what counted, and what didn't. Drugs and debauchery, for example? No problemo.

"Venus for me!!" she texted, the exclamation marks belying her bloodshot eyes and wobbly posture.

"There are a limited number of spots," Kristiansen replied. "And one of them's mine."

So he wanted Venus, too. Well, everyone did. In the year 2277, the only reason people joined the Space Corps was to get assigned to the United Nations Venus Remediation Project. This screamingly ambitious scheme to terraform the planet Venus had seized the imagination of a whole generation. UNVRP was the new frontier, pushing the envelope of possibility, in a solar system where it could seem that technology's limits had already been reached.

Those limits, however, encompassed some achievements that previous generations would have found fantastical. He3-deuterium fusion drives could take passengers from Earth to Jupiter in less than a year, making several stops in the Belt en route. Precisely calibrated gravitational assists enabled ships to land on the Jovian moons, deep within Jupiter's gravity well. Human colonies dotted the Belt in an ever-expanding nimbus of entrepreneurial zeal. And there was a large, vibrant colony on Ganymede, whose trailing hemisphere sucked up 8 rems per day of killing radiation, and whose surface temperature plunged as low as –180° C at night.

"So, you may be wondering, how do we stay alive out here?" a voice drawled.

None of the 77'ers thought of replying. They were sprinting across the ice, towards the rovers. They wore EVA suits with outer-system temperature tolerances and the best integrated shielding that UN taxpayer money could buy. Nevertheless, Elfrida hardly dared to look at the radiation counter in her faceplate's display, which was clocking up the millirems at terrifying speed. They were all one stumble away from maxing out their EVA allowances for the year. This is the first test, she thought.

"We hide," the voice said.

There was a trick to running fast in microgravity: keep your feet together and hop like a kangaroo. While bounding along like this, Elfrida managed to steal a look at Jupiter.

Wowzalmighty! she thought, grateful that her life had included this moment.

The gas giant filled more than half of Ganymede's black sky. Flawed jewel, failed star, king of the planets, it lit the ice of Neith Crater with a toasty glow. She spotted Ganymede's shadow, a black dot on the ivory equatorial band.

And then her assigned rover loomed over her. It had no airlock, just a hatch under its skirt of icicles. Elfrida climbed into an unpressurized steel box. More trainees pushed in, some of them flipping upside-down in their haste. They were packed in helmet to ass. The rover was a lot smaller on the inside than on the outside.

"Four-fifths of this rover's mass is ice," said their friendly guide. "It's a regular four-ton crawler, like you see everywhere. We print out plastic molds contoured to its shape, fill 'em with water, let em freeze. Hey presto, instant radiation shielding."

The rovers drove into a hole in the ground, which turned out to be the spaceport terminal. Bots trundled between administrative domes and stacks of cargo containers. There was a tram station—that was what it looked like, anyway. People in spacesuits stood waiting on a loop-shaped platform. The 77'ers disembarked and shuffled onto the platform.

A sleek capsule coasted out of a hole in the wall. They got in and took their seats. The capsule glided around the loop—and plunged straight down.