Space Boffins Sue Nelson and Richard Hollingham are on Mars - which turns out to be behind a blue door in the Hertfordshire town of Stevenage. With guest Airbus head of science, Ralph Cordey, they discuss the final moments of Rosetta, Europe's latest mission to Mars - due to land in October - and Elon Musk's plans for martian colonisation. Sue reports from ESA's mission control in Germany and Richard hears about the fastest man on Earth. They also catch-up with J Willgoose Esq from the band Public Service Broadcasting.