Lifeburst

Lifeburst, Jack Williamson, Del Rey Books, 1984

The Seekers were cyborg war machines in a war eons ago. They subsisted on a diet of heavy metals, the more radioactive, the better, and destroyed all life in their paths, including their creators. Now a pregnant Seeker has made a nest in the solar system's asteroid belt.

Meantime, in the mid 2100s, Earth is totally ruled by the Sun Corporation. There are two kinds of people on Earth: those who have been genetically tested on their ability to withstand long periods in outer space, and those who are not so lucky.

Quin Dain is one of the unlucky ones. Having spent his whole life at a research station on an asteroid in the Oort Cloud, far beyond Pluto, he wants nothing more than to actually walk on Earth. One of the factions fighting for control of the Sun Corporation is totally convinced there is no such thing as aliens, so the research station is closed. The people there decide to go it alone, and send Quin to Earth to bring back a new type of fusion engine to power the station.

Williamson has been publishing for more than 70 (that's right, 70) years, so he really knows how to tell a story. This is a strong, well done and quite satisfying novel.