And there were the rings of the calderas around them, jutting far into the sky even when the two walkers were out in the center of the central circle, out where the later, deeper calderas appeared as big embayments in a single wall’s roundness. Out here the planet’s sharp curvature had no effect on one’s perspective, the curve was for once invisible, the cliffs free and clear even thirty kilometers away. The net effect, it seemed to Sax, was of a kind of enclosure. A park, a stone garden, a maze with only one wall separating it from the world beyond, the world which, though invisible, conditioned everything here. The caldera was big but not big enough. You couldn’t hide here. The world poured in and overflowed the mind, no matter its hundred-trillion-bit capacity. No matter how big the neural array there was still just a single thread of awed mentation, consciousness itself, a living wire of thought saying rock, cliff, sky, star.

• • •

The rock became heavily cracked by fissures, each one an arc of a circle with its center point back in the middle of the central circle: old cracks relative to the big new holes of the north and south circles, old cracks filled with rubble and dust. These rock crevasses made their walk into a wandering ramble— in a real maze now, a maze with crevasses rather than walls, yet just as difficult of passage as a walled one.

But they threaded it, and finally reached the rim of north circle, number 2 on Sax’s map. Looking down into it gave them a new perspective— a proper shape to the caldera and its circular embayments, a sudden drop to a heretofore hidden floor, a thousand meters below.

Apparently there was a climbing route down onto the floor of north circle; but when Ann saw the look on his face as she pointed it out— achievable only by rappelling— she laughed. They would only have to climb up out of it again, she said easily, and the main caldera wall was already tall enough. They could hike around north circle to another route instead.

Surprised by this flexibility, and thankful for it, Sax followed her around the north circle on its west circumference. Under the great wall of the main caldera they stopped for the night, popped the tent, ate in silence.

After sunset Phobos shot up over the western wall of the caldera like a little gray flare. Fear and dread, what names.

“I heard that putting the moons back in orbit was your idea?” Ann said from her sleeping bag.

“Yes, it was.”

“Now that’s what I call landscape restoration,” she said, sounding pleased.

Sax felt a little glow. “I wanted to please you.”

After a silence: “I like seeing them.”

“And how did you like Miranda?”

“Oh, it was very interesting.” She talked about some of the geological features of the odd moon. Two planetesimals, impacted, joined together imperfectly. . . .