She was amazed by the transparency of the air. There was a sense of depth to the atmosphere, a three-dimensional appearance that surprised her. There were shadows under the clouds as they slid across the face of the seas. The clouds thickened toward the equator, and when she looked ahead, tangential to the Earth’s surface, she could see them climbing up into the atmosphere, as if Ares was heading for a wall of vapor. On the land she could easily make out cities — a gray, angular patchwork — and the lines of major roads. The orange-brown of deserts was vivid, but the jungles and temperate zones were harder to spot; their color did not penetrate the atmosphere so well, and they showed up as a gray-blue, with the barest hint of green.

She found the lack of green disappointing.

She saw the wake of a ship, feathering out like a brushstroke on the sea’s calm surface.

Gershon, in his center seat, leaned toward her. “Quite a view, huh.”

She turned her head — and quickly regretted it; her head felt like a tank of fluid, sloshing when she moved. She held her head steady for a few seconds and let the sloshing settle down again. Resolutely, she tried not to think about her stomach.

Space adaptation syndrome. She understood what was happening to her. Without gravity, little particles of calcium on sensitive hairs in the inner ear took up random positions, and the body couldn’t work out which way was up. It generally went away after a few days.

But just now it was a huge embarrassment to York.

More carefully, she turned back to the window. They were passing over storm clouds, thunderheads which piled up on top of each other as if solid, cliffs and ravines of cloud miles deep. She could see lightning, sparking in the clouds like living things, propagating across storm systems thousands of miles across. The clouds, illuminated from within, glowed purple-pink, like neon sculptures. “Look at that. It looks as if the thunderheads are reaching up toward us.”

“Only about a tenth of the way,” Gershon said mildly.

“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.