As John Glenn returns to from space a new analysis emphasises the risks of space travel. Meteoric rise into space Chart John Glenn's trajectory to fame - from young Navy cadet to national hero. Hear John Glenn make history Listen to the epic moments in Glenn's space career. Astronomical costs This century has seen the greatest achievements in space exploration - and there's more to come.
Space age Turn the clock back by travelling to the stars at the speed of light.
It works, in theory at least.