A mission to Mars, from physicist-author Benford (Cosm, 1998, etc.), is both a race to reach the red planet and a living race of Martian biota. Early in the next century, the US government balks at NASA’s $450-billion, pork-barrel—inflated venture. Instead, Uncle Sam offers a Mars Prize of $30 billion to the first manned expedition to return successfully to Earth. Step forward, wealthy bio-industrialist John Axelrod: to fund an expedition, he’ll allocate his own money and sell the rights to everything concerning the endeavor. To return, the astronauts can grab NASA’s abandoned ERV lander (sent before the budget cuts, it’s ready and waiting on Mars). But captain Viktor Nelyubov, his wife, Julia Barth, and their companions have competition: the Chinese/European Airbus consortium’s nuclear-powered spaceship will be able to make the trip faster and with less fuel. When Julia and company set up housekeeping on Mars, they discover a honeycomb of warm, damp tunnels containing “marsmat,” an extensive, complex anaerobic life-form, and decide to conceal the discovery. But the planet’s corrosive peroxide dust and a rough landing have damaged the ERV. The Airbus ship arrives with a repair kit, but the ERV’s still kaput. Worse, their rivals skim off Julia’s scientific results and prepare to zip back to Earth and claim the prize. Then, two Airbus researchers locate Julia’s marsmat, only to die in a grotesque accident when it reacts to their presence. So, who will return in the Airbus ship, and who will stay on awaiting rescue? Taut, plausible, and full of ideas.