Overview: Mars captures the imagination like no other planet and currently our nearest neighbour is at its brightest for several years, so it's a perfect opportunity to explore a planet that is tantalisingly similar to our own. And in the past it may have been even more like Earth, an inviting and habitable place, a perfect environment for life to flourish. Geologist Iain Stewart investigates how we can read the story of Mars's extraordinary past from its rocks, Maggie Aderin-Pocock comes face to face with the latest Mars rover and Chris Lintott meets the man behind the discovery which the whole history of the universe now rests upon.