Episode details
Available for over a year
Dr Karls answers questions about moon phases, NASA's record on the Voyager space probe, and hydrogen cars.
Programme WebsiteUse BBC.com or the new BBC App to listen to BBC podcasts, Radio 4 and the World Service outside the UK.
Available for over a year
Dr Karls answers questions about moon phases, NASA's record on the Voyager space probe, and hydrogen cars.
Programme Website