Little green men, or microscopic blobs? For centuries, the prospect of life on Mars has brought the most lethargic imaginations to the boil, and driven scientists to a frenzy of speculation. But a team of University of Toronto physicists, working with other Canadian and American experts, hopes its landmark research mission will be among the first to answer the interplanetary riddle, and deliver new information that will pave the way for the great race to the Red Planet.