It’s all a symptom of the clumsy way we’re constrained to do this, the lousy technology. One day, maybe we’ll have the power and energy to do this journey in something resembling comfort, without having to take the damn spacecraft apart all the time.

The assembled craft had none of the detailed, toylike brilliance she had observed about ships in Earth orbit. After a year in space, the brilliant white paint of prelaunch had faded to a pale yellow; and the shadowed areas of the hull were picking up brown shading from the battered skin of Mars. The cluster looked aged, soaked in space.

When Ares had receded from view she could see nothing through the little window but darkness.

Darkness, and, occasionally, a sliver of ocher landscape.

Challenger flew over the shadowed limb of Mars.

“Thirty seconds to DOI,” Stone said. “Everything’s go.”

“I confirm a go,” Gershon said.

DOI: insertion into descent orbit — a new, low, elliptical orbit, an orbit that would intercept the surface of the planet.

York could see Gershon’s hand, hovering over the manual fire button. Challenger was Gershon’s baby, of course; the landing — the next few minutes — were the culmination of a decade of work for him. He looked keyed up to York, tense, expectant.

Sims were spring-loaded to fail. That was the point, really: to familiarize crew and controllers with all the myriad ways the mission could go wrong, and train them to cope. However, York had the feeling that Ralph Gershon was spring-loaded the other way. It is going to take a lot to keep him from landing this bucket of bolts.

And that, as far as York was concerned, was good.

“Fifteen seconds,” Stone said. “Ten seconds to DOI. Here we go, guys. Eight. Six, five, four.”

Gershon’s gloved hand closed over the firing button.

“Two, one.”

The rockets fired in sequence. It was a muffled, rattly noise.

And then came the jolt, deep in her back.

“Retro light on.” Gershon flashed a grin. “Beautiful! Pure gold!”

It felt as if Challenger had been knocked backwards. Solid rockets, she’d been told, always burned a lot more crisply than liquid.

The burn went on, with Stone counting up the time. The rockets’ thrust of forty thousand pounds force was too small to shove seriously at the mass of the MEM, and so there was no rattle, no vibration, no real sense of deceleration. Just a steady push at her back, a smooth hiss as the retropack burned.

The push died sharply. Right on cue, the retropack had cut out.

Nothing felt different. Challenger was still in orbit around Mars, for the time being, and York was still weightless, floating within the restraints which held her to her couch.

But the MEM was following a path that would bring it arcing down until it sliced into the Martian atmosphere, at maybe thirty miles above the surface. And the drag of the atmosphere would not allow the craft to climb out again.

Challenger was committed to Mars.

Suddenly she got an unwelcome sense of perspective, a feeling of how small and fragile the little capsule was. It was different from landing on Earth. On Earth you were descending toward an inhabited planet, toward oceans full of ships waiting to pick you up.

Out here there were only the three of them, jammed up against each other in their little pod, descending toward a dead world. So far from Earth they couldn’t even see it. Out here, they weren’t closing off their journey, coming home; out there, they were pushing out still farther, into extremes of technological capability and risk, so far from Earth that Mission Control couldn’t even speak to them in real time. It was like climbing the ladder one more rung.

But what York felt was not fear, but mostly relief. Another abort threshold crossed. The farther the mission went, the fewer things were left to go wrong.

“Coming up on jettison retro,” Gershon said.

Stone counted him down. “Three, two, one.”

York heard a muffled bang as pyrotechnic charges broke the metal belt holding the small retropack against the base of Challenger. Then there was a clatter against the wall, oddly like the footsteps of a huge bird: that must be the belt of the discarded pack, scraping along the hull.

With the retropack gone, Challenger was falling ballistically, like a projectile shot out of a gun. Its heat shield gave it the form of a blunt cone, the classic Command Module shape, though the MEM was nearly three times as big as an Apollo CM.

Gershon tipped up the spacecraft, so that the blunt prow of its base, where the titanium honeycomb heat shield was thickest, led the way into the gathering air. When he fired the attitude thrusters York saw brief bursts of gray mist, beyond the small window above her.

Then the mist got more persistent, in short bursts of translucent paleness, that lingered even after Gershon had stopped firing.

Soon the mist started to turn pink. There was a thin whistle beyond the hull.

The glow was the air of Mars, its atoms smashed to fragments by impact with Challenger’s heat shield.

Gershon whooped. “We’re getting close! Old papa Mars has us!”

“Goddamn,” Stone said, his voice tight.

The first feather touches of deceleration settled over York: a gentle pressure inside her stomach, a faint heaviness about her legs.

A light went on at Gershon’s station.

“Gotcha!” he shouted. “That’s point zero five G. This is going to be a real ride. Hang on.”

Point zero five G: the traditional threshold of atmospheric drag. And here they were, reaching point zero five G in the air of Mars.

The deceleration piled up on her in sudden, brutal steps. It’s bumpier than the sims. This air is supposed to be thin, damn it. There must be a more complex structure of layers in the atmosphere than had been realized, a sharper differentiation.

The pain at her chest was already exquisite.

She kept her eyes wide-open, trying to remember every detail. Every ounce of pain will tell someone, some atmospheric scientist, more about Mars. After all, she might be one of just three people in history to endure this.

Somehow, though, at this moment it wasn’t worth it.

She heard the crisp rattle of the attitude control thrusters’ solenoids.

Gershon watched his guidance display. “Right on track. One forty-seven degrees…”

Challenger had to hit a precise reentry corridor. The allowable guidance error either way was only half a degree: less than fifty miles wide.

“Coming up on one G… now.”

Just one G? Already York felt as if her suit was made of lead tubes, as if some fat man was sitting on her chest. Can this really be Earth-normal gravity? After a year in microgravity, the burden seemed intolerable, like carrying a huge pack around on your back, for your whole life.

“One point five,” Stone said.

York groaned. She was pushed deep into her couch, her arms pressed into her body; the small components of the weights of Gershon and Stone which rested on her became immense loads.

“Hang on, guys,” Stone said. “One point eight. You’ve been through a lot worse in the Wheel. Two point one.”

Gershon worked at his guidance panel, his hand hovering over his RCS control.

“Two point five,” Stone said. “Point six!… Point five. Point three. Hey, what did I tell you.”

The light in the small window above York had become a gray-white glow, cold and brilliant, as bright as Earth daylight. Gershon and Stone were bathed in the diffuse, unearthly light, the orange of their suits washed-out, their faces invisible behind the reflections from their faceplates. It was like being inside some huge, complex fluorescent light tube.

The weight on her chest and legs began to slacken off. She could feel her chest expand, her breath flowing more easily into her lungs.

Something went flying past the little window overhead, small and brilliant, glowing yellow. Flaming. It was a piece of the heat shield, melting off the base of the craft, carrying the lethal heat energy away from the capsule. More pieces came flying past, fist-sized or bigger, some of them rattling on the hull of the cabin.