It’s all systems go in space as the crew of the shuttle Discovery gears up for the descent back to Earth tomorrow morning. The astronauts say they are confident their return will be safe. “I think Discovery is in absolutely great shape. It performed well in ascent. This morning we did a flight control system checkout, everything checked out fine,” said Discovery Commander Eileen Collins. During the 13-day mission one of the astronauts had to carry out an unprecedented repair during a space-walk to fix damage sustained during take-off. One of the first steps of the journey home passed off smoothly with Discovery safely undocking from the International Space Station yesterday. This is Nasa’s first shuttle mission since the Columbia disaster in 2003 when the shuttle broke up on re-entry, with the loss of all seven crew members. Though Discovery has been given a clean bill of health for its Florida touchdown, Nasa officials admit this will be a nail-biting ride.