After 40 years of missions to Mars, its secrets could finally be within our reach.
Forty years on, Mars is still a place of fascination for humanity, though its investigation has been a rocky business. "The story of Mars exploration has been a real rollercoaster," admits Oxford astronomer Professor Fred Taylor, who has worked closely with Nasa on a number of missions to the planet. "Once, it seemed destined to support life. Then we thought it was utterly dead and featureless. Then we discovered – thanks to Mariner 9 – that it had a landscape through which water had poured. After that, craft found its soil contained no signs of biological material. Since then, we have bounced back and are hopeful life may exist deep underground."