Geologist Sanjeev Gupta talks to Jim Al-Khalili about his love of exploring exotic terrains, from the foothills of the Himalaya to the red deserts of Mars. His research has taken him across the earth and now into space, working as a Long Term Planner on NASA's current Mars Curiosity Mission.But Sanjeev Gupta's big discovery lay at the bottom of the English Channel. Unearthing a 'wacky' theory from the 1980s, Sanjeev set out to prove that a series of megafloods caused Britain to separate from continental Europe and become an island.Producer: Michelle Martin.