Incoming! NASA's acting head of planetary defence, Kelly Fast, discusses asteroids, YR2 and how to protect our planet. The UK Space Agency's head of Earth Observation and Climate, Beth Greenaway, and chief scientist, Shaun Quegan, discuss the upcoming European Biomass mission to measure how much carbon is being stored in tropical forests. And Kelly Weinersmith - co-author of A City On Mars - explains why living on the red planet will be much harder than anyone thought... Like this podcast? Please help us by supporting the Naked Scientists