The last in the series in which Robbie Coltrane examines bold attempts to push forward the limits of design.
In this week's programme, the race is on to design the ultimate robot drill. Its seemingly impossible task is to catch up with a comet some 600 million kilometres from Earth and, in zero gravity, drill into its forbidding surface.
(Stereo)
Booklet: For a booklet on engineering, telephone: [number removed] (calls cost 39p per minute cheap rate, 49p per minute at all other times), or access the World Wide Web on: [web address removed]