“Pressure’s okay,” Stone said. He began to take off his gloves and helmet.

York unlatched her gloves and pulled them off, then shoved them into a pocket on her couch. She grasped the sides of her helmet, which came loose with a click; she pushed it up over her head.

She moved too quickly. Suddenly her head was full of sloshing fluid again, and saliva flooded her mouth.

Her helmet, rolling loose, clattered against a bank of switches. Gershon grabbed it easily, laughing. “Interception!” In his pressure suit he looked small, compact, comfortable. He threw the helmet up in the air again with a twist; the helmet revolved, oscillating about two spin axes.

York felt embarrassed, clumsy. And, watching the helmet, suddenly she was retching.

“Oh, man,” Stone said in disgust. He handed her a plastic bag, and York fumbled it open, and pushed her face into it.

As she heaved, a greenish sphere, about the size of a tennis ball, came floating up out of the bag. It was shimmering, and complex pulsations crossed its surface.

York watched in awe. Maybe I ought to film this. It was a demonstration of fluid mechanics, in the absence of gravity; she wondered if the wave patterns, dominated by surface tension, could be predicted by computer.

The glob of vomit split in two. One half headed toward the wall, and the other made straight for Gershon.

“Ah, shit,” Gershon said, and he tried to squirm out of the way.

The glob hit him in the chest, with a soft impact; it immediately collapsed and spread out over his suit, as flat as a fried egg. Surface tension again, York thought absently.

“Oh, Jesus,” Gershon said. “Oh, shit.”

Stone reached for wet wipes, and passed some to Gershon. “Come on, man. It might have been any of us. We’ve got to get this place cleaned up.”

So they began chasing around the cabin, hunting down bits of vomit with paper towels and plastic bags.

Once her stomach awareness had receded a little, York found, oddly, that it wasn’t actually so unpleasant. It was a little like chasing butterflies.

“NC One phasing burn,” Stone said. He held down the thrust control, watching his instruments.

The burn felt tight and rattly to York. She was shoved into her couch again; the acceleration was low, but crisp.

Through her window she could see vapor venting from attitude control thruster nozzles; the vents looked like fountains of ice crystals, the particles receding from the walls of the craft in precise straight lines.

The burn was taking place over the nightside of Earth. The planet pulled away; it was as if she were rising above a floor of dark, frosted glass. The continents were outlined by chains of brilliant dots, like streetlights seen from the air. But those dots weren’t streetlights; they were towns.

She twisted in her seat and looked ahead, toward the limb of the planet.

She could see the airglow layer, the bright layer of ionized oxygen at the top of the atmosphere, a fine line that was like a false sunrise. And then, as she watched, a sliver of sky turned blue and spread along the horizon. More colors came up, coalescing around a bright patch that was the rising sun, a spectrum that washed around the curve of Earth. The light of the dawn reached her through the layer of atmosphere; for a brief moment she saw the shadows of the clouds streaming across the orange surface of the sea.

Then the sun rose high enough to illuminate the tops of the clouds. The sea turned to crimson, and a wash of pale blue and white spread from the horizon toward her.

On a whim, she dug into a pocket of her pressure garment and pulled out the handful of grass which Vladimir Viktorenko had given her. She held it in her palm and rubbed it gently; it gave off a sweet aroma, like a herb. It was polin, a kind of wormwood, common all over the Kazakhstan steppe.

Stone finished the burn. His push-button control, released, popped back out of the panel on its spring. “Two hundred seven feet per second,” he said.

“Right on the wire,” Gershon murmured. “One hundred ninety-five times two hundred zero one.”

Young called up, “Copy your burn, Ares. You are two hundred fifty miles from the stack, and closing.”

“Copy, John. Preparing for NC Two…”

The crew had arrived in orbit with half the Ares cluster: their Apollo Command and Service Modules, the Mars Excursion Module — the MEM — and the Mission Module, their habitat for the journey. The rest of the cluster — the main injection booster and its huge fuel tanks — had already been placed in orbit and assembled, ready for them to dock with it.

The Mission Module was a squat cylinder, with the Apollo a slim, silvery cylinder-cone attached to its front, and the MEM — a fatter, truncated cone — stuck on the back. Fixed to the base of the MEM’s shroud was an Orbital Maneuvering Module, a fat doughnut fitted with a modified Apollo Service Module propulsion system. The OMM would be discarded before they docked with the booster cluster. But first Stone had to use the OMM in a series of four burns, to chase the booster cluster around the sky.

Stone announced: “Ready for NCC.”

“Copy,” Young said. “Ninety miles and closing.”

The corrective burn was crisp and short, a brief hiss.

Stone murmured, “Natalie, you ought to be able to see the booster by now. Right out front.”

York pressed her face to the window. The brief burns were placing Ares on segments of successively wider orbits; following the new orbits, Ares would eventually overtake the booster stack.

The craft was noticeably higher than when they had first been injected into orbit; the curvature of the Earth was much more pronounced, and she was able to see complete landmasses, speckled with cloud.

Suddenly it was there: a pencil, gleaming silver, hanging over the dipping horizon.

“I have it.”

“That’s a relief,” said Stone drily. “Okay, Houston, I’m going for the twenty-eight feet per second coelliptic combination burn.”

“Copy, Phil.”

Another sharp rattle.

Young said, “Slight underburn that time, Ares. One point six feet per second.”

“Copy that,” said Gershon, and he clucked at Stone in mock disapproval.

Young said, “Your orbit is now ten miles under the booster’s. Range sixty-three miles and closing.”

“Rog,” Stone said. “Going for terminal phase initiation.” York could hear solenoids clatter as Stone worked the push-button controls of the reaction control clusters. “How about that. Right down Route One.”

“Good burn, Ares,” Young said. “You’re closing at one hundred thirty-one feet per second.”

Stone went through two more corrections, and five sharp braking maneuvers. Then, maybe half a mile from the booster, he took the Apollo on a short, angular inspection sweep. The reaction control systems bit sharply, rattling York against her restraint.

York watched the cluster roll with silent grace past her window.

The booster cluster was squat, pregnant with fuel. Its heart was a fat MS-II booster, a Saturn second stage, modified to serve as an orbital injector. Fixed to the front of the MS-II was an MS-IVB, a modified Saturn third stage, a narrower cylinder. To either side of the MS-II were fixed the two External Tanks, fat, silvery cylinders as long and as wide as the MS-II stage itself. The supplementary tanks carried more than two million pounds of liquid oxygen and hydrogen, propellant Ares would need to break clear of Earth orbit.

The MS-II and its tanks looked like three fat sausages, side by side, with the slimmer pencil shape of the MS-IVB protruding from the center. The rest of the Ares stack — the Mission Module, MEM, and Apollo — would be docked onto the front of the MS-IVB to complete the assembly of the first Mars ship, a needle well over three hundred feet long.

The cluster was oriented so that it was pointing toward the sun; that way, boiloff of the cryogenic propellants inside the tanks was reduced. Shadows of struts and attitude thrusters lay long against the sunlit white-and-silver bellies of the fuel tanks. The booster’s underside was illuminated only by the soft blue and green of Earthlight. She could see the great flaps of the cluster’s solar panels, folded up against the sides of the MS-IVB stage like wings; the panels would be unfurled when Ares was safely launched on its trajectory to Mars. There was the bold red UNITED STATES stenciled against the side of the MS-II, and the finer lettering along the long thin protective flaps masking the solar panels, and the NASA logo; and she could make out the support struts and attachment pins which held the External Tanks in place against the flanks of the MS-II, and the gold-gleaming mouths of the MS-II’s four J-2S engines, upgrades of the engines which had pushed Apollo to the Moon.