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When Ellen Stofan was just four years old, she witnessed the worst rocket launch-pad disaster in NASA's history convinced that her father, (who was a rocket engineer) was on board. He wasn't. Nonetheless, for many years NASA was not her favourite place. In 2013, however, she became she became their chief scientist, a post she held for 4 years. Barak Obama dreamt of putting people on the red planet by 2032 and Ellen did everything she could to develop a realistic plan to make this happen. (A 2032 arrival is ambitious but NASA is considerably closer than it was before Ellen took charge of the science.)

Her research career began studying radar data from a Soviet mission to Venus, trying to see beyond the thick toxic cloud that surrounds it. She wanted to understand how Venus evolved so very differently from its nearest neighbour, earth. She has also used radar data from satellites to study planet earth. And in 2008, was the lead author on a paper that revealed the extent of the lake on Saturn's moon, Titan. It contains hundreds of times more gas and liquid hydrocarbons than all the known oil and natural gas reserves on earth.

Producer: Anna Buckley.