The giant ships that would fly on the fifth manned mission to Jupiter had been under construction in Lunar orbit for over a year. Besides the command ship, six freighters, each capable of carrying thirty thousand tons of supplies and equipment, gradually took shape high above the surface of the Moon. During the final two months before scheduled departure, the floating jumbles of machinery, materials, containers, vehicles, tanks, crates, drums, and a thousand other items of assorted engineering that hung around the ships like enormous Christmas-tree ornaments, were slowly absorbed inside. The Vega surface shuttles, deep-space cruisers, and other craft also destined for the mission began moving in over a period of several weeks to join their respective mother ships. At intervals throughout the last week, the freighters lifted out of Lunar orbit and set course for Jupiter. By the time its passengers and final complement of crew were being ferried up from the Lunar surface, only the command ship was left, hanging alone in the void. As H hour approached, the gaggle of service craft and attendant satellites withdrew and a flock of escorts converged to stand a few miles off, cameras transmitting live via Luna into the World News Grid.

As the final minutes ticked by, a million viewscreens showed the awesome mile-and-a-quarter-long shape drifting almost imperceptibly against the background of stars; the serenity of the spectacle seemed somehow to forewarn of the unimaginable power waiting to be unleashed. Exactly on schedule, the flight-control computers completed their final-countdown-phase checkout, obtained "Go" acknowledgment from the ground control master processor, and activated the main thermonuclear drives in a flash that was visible from Earth.

The Jupiter Five Mission was under way.

For the next fifteen minutes the ship gained speed and altitude through successively higher orbits. Then, shrugging off the restraining pull of Luna with effortless ease, Jupiter Five soared out and away to begin overtaking and marshalling together its flock of freighters, by this time already strung out across a million miles of space. After a while the escorts turned back toward Luna, while on Earth the news screens showed a steadily diminishing point of light, being tracked by the orbiting telescopes. Soon even that had vanished, and only the long-range radars and laser links were left to continue their electronic exchanges across the widening gulf.

Aboard the command ship, Hunt and the other UNSA scientists watched on the wall screen in mess twenty-four as the minutes passed by and Luna contracted into a full disk, partly eclipsing that of Earth beyond. In the days that followed, the two globes waned and fused into a single blob of brilliance, standing out in the heavens to signpost the way they had come. As days turned into weeks, even this shrank to become just another grain of dust among millions until, after about a month, they could pick it out only with difficulty.