Heirs of the New Earth — David Lee Summers

The Earth has gone silent. John Mark Ellis and the crew of the Sanson are sent to investigate. When they arrive, they find vast alien machines known as Clusters in orbit. Fearing the worst, they land and discover that the once overcrowded, polluted Earth has become a paradise of sorts. The problem is over half the population is dead or missing and the planet's leaders don't seem to care. As Ellis works to unravel the mystery, sudden gravitational shifts from the galaxy's center indicate something even worse is in the offing. Can Ellis save the galaxy from the heirs of the new Earth?