Is there life on Mars

NASA's Curiosity rover has detected the periodic release of methane from samples it has taken of the Martian surface. The excitement in some quarters is almost tangible as the presence of methane, the archetypal organic compound, might tantalizingly be due to the presence of a microbial lifeform. Or not. NASA scientists do not yet know whether the methane is being released by a physical rather than biological process. The methane is coming from Sheepbed mudstone in the Gale crater, the landing site of Curiosity and while the evidence does not exist for a biological origin, there is evidence for water at the same site, which hints at the crated having been a vast lake long ago.