They had chosen their own landing site on one of the ridges between facets, where lighter bare rock protruded from the blanket of dust. The ridges were old spallation scars, marking where early impacts had knapped pieces of the moonlet away. Jackie brought them down gently toward a ridge to the west of Swift and Voltaire craters. Deimos was tidally fixed, as Phobos had been, which was convenient for their project. The sub-Mars point served as 0° for both longitude and latitude, a most sensible plan. Their touchdown ridge was near the equator, at 90° longitude. About a ten-kilometer walk from the sub-Mars point.

As they approached the ridge, the rim of Voltaire disappeared under the black curved horizon. Dust blew away from the ridge as the plane’s rockets shot exhaust over it. There was only a few centimeters of dust covering the bedrock. Carbonaceous chondrite, five billion years old. They docked with a hard thump, bounced away, slowly drifted down again. He could feel the pull toward the floor of the plane, but it was very slight. Probably he didn’t weigh more than a couple of kilograms, if that.

Other rockets began to land on the ridge to either side of them, kicking clouds of dust into the vacuum, where they drifted slowly down. All the planes bounced on impact, then came down gently through their dustclouds. Within half an hour there were eight planes lined up on the ridge, running along it to the tight horizons in both directions. Together they made a weird sight, the intermetallic compounds of their rounded surfaces gleaming like chitin under the surgical glare of unfiltered sunlight, the clarity of the vacuum making all their edges overfocused. Dreamlike.

Each plane carried a component of the system. Robot drillers and tunnelers and stamps. Water-collection galleries, there to melt the veins of ice in Deimos. A processing plant to separate out heavy water, about one part in 6,000 of the ordinary water. Another plant to process deuterium from the heavy water. A small tokamak, to be powered by a deuterium-deuterium fusion reaction. Lastly guidance jets, though most of these were in planes that had landed on the other sides of the moon.

The Bogdanovist technicians who had come up with the equipment were doing most of the installation. Sax got suited up in one of the bulky pressure suits on board, and went out the lock and onto the surface, thinking to look and see if the plane carrying the guidance jet for the Swift-Voltaire region had landed.