Sending astronaut is 'enormous logistical problem'
20 May 2013 Last updated at 10:25 BST
Tim Peake is expected to be unveiled as the first British astronaut to fly to the international space station on Monday.
He may not be the first British astronaut - but he is the first taxpayer-funded one. He is costing the public £16m - a major leap for the British in space.
Colin Pillinger, famous for the "Beagle 2 Mars" mission, told the Today programme: "It's an enormous logistical problem in order to get one astronaut into space."
But he added: "Don't underestimate the value of sending an astronaut."
Kevin Fong, director of the Centre for Space medicine at UCL, said: "Almost anyone can qualify for space flying, but the professional astronauts do really have to have the right stuff - team players, lots of determination and tolerance."
First broadcast on the Today programme on Monday 20 May.