“I have to concentrate to do it. I have to think hard. Things surprise me all the time. Things I used to know and forgot. Things I never knew. Things I learned just before the injury. That period is usually occluded forever. But it was so important. When I was working around the glacier. I have to talk to your mom about that. It isn’t like she thinks. You know, the land. The new plants out there. The yellow butterfly sun. It doesn’t have to be . . .”

“You should talk to her.”

“She doesn’t like me.”

“Talk to her when we get back.”

The altimeter indicated 250 kilometers above the surface. The plane plowed up toward Cassiopeia. Every star had a distinct color, different from any other. Or there were at least fifty of them. Below them, on the eastern edge of the black disk, the terminator appeared, zebra-banded sandy ochre and shadowy black. The thin crescent of sunlit Mars gave him the sudden clear perception of the disk as a great spheroid. A ball spinning through the galaxy of stars. The great huge continent-mountain of Elysium bulked over the horizon, its shape perfectly delineated by the horizontal shadows. They were looking down the length of its long saddleback, Hecates Tholus almost hidden behind the cone of Elysium Mons, Albor Tholus off to the side.

“There it is,” Peter said, and pointed up through the clear cockpit. Above them, to the east, the eastern edge of the aerial lens was silver in the morning light, the rest of it still in the planet’s shadow.

“Are we close enough yet?” Sax asked.

“Almost.”

Sax looked down again at the thickening crescent of the morning. There on the dark rough highlands of Hesperia, a cloud of smoke was billowing up from the dark surface just beyond the terminator, into the morning light. Even at their height they were in that cloud still, in the part that was no longer visible. The lens itself was surfing on that invisible thermal, using its lift and the pressure of sunlight to hold its position over the burn zone.

Now the entire lens was in the sunlight, looking like an enormous silver parachute with nothing underneath it. Its silver was also violet, sky-colored. The cup was a section of a sphere, a thousand kilometers across, its center some fifty kilometers above its rim. Spinning like a Frisbee. There was a hole at the peak, where the sunlight poured straight through. Everywhere else the circular mirror strips that made up the cup were reflecting the light from the sun and the soletta, inward and down onto a moving point on the surface below, bringing to bear so much light that it was igniting basalt. The lens mirrors heated up to almost 900K, and the liquefied rock down there was reaching 5,000K. Degassing volatiles.