Brave astronauts find themselves on a one way trip to the sun – can International Rescue help them in time or are they too doomed to face death by extreme temperature? 'Sun Probe' is a fan favourite, but how did it look when first planned as a half hour episode in 1964? In this behind the scenes look at the episode's production and attempt to uncover the original 25 minute version of the story using behind the scenes material and on-screen clues. https://www.youtube.com/watch?v=dJ1B2ijF_9A