Stephen Baxter 
Moonseed 

Venus has exploded.Showering Earth with radiation and bizarre particles that wipe out all the crops and half the life in the oceans.Suddenly, the ground itself begins melting into pools of dust that grow larger every day. For what has demolished Venus, and now threatens Earth itself, is part machine, part life-form — a nano-virus, dubbed Moonseed.Four scientists are all that stand between Moonseed and Earth’s extinction, four brilliant minds that must race to cut off the virus and save what’s left of the planet.