The American space agency NASA has set a May 15 launch date for the first space shuttle launch since the Columbia disaster two years ago.
When the space shuttle Discovery lifts off in May, veteran astronaut Eileen Collins will be in command. She and her crew are confident NASA has done everything possible to make this a safe flight.
"We know every flight will not be perfect and I'm not going to stand here and say there is still risk in space flight and I think there will always be risk in space flight,” says Eileen Collins.
NASA has spent the two years since the space shuttle Columbia broke apart during reentry trying to reduce the risk.
The external fuel tank has been redesigned to minimize the chance of foam breaking off and punching a hole in the orbiter. That's what doomed Columbia. Flight Director Paul Hill believes this will be the safest shuttle flight ever.
"We've gone to great lengths to minimize the risk of debris coming off anywhere of the vehicle during the assent, so we have reduced the risk. Is it zero, No, but it's smaller today than it has ever been,” says Paul Hill.
NASA has also taken steps to better detect damage, installing new sensors in the wing panels and developing a boom arm with lasers that will allow astronauts to examine the shuttle for damage while in orbit.
One thing NASA has learned since the Columbia tragedy is that even small damage could cause the shuttle to break apart on reentry. NASA is still struggling with a reliable way to repair holes in the critical heat protection tiles while the shuttle is in space. Several techniques show promise including a silicone paste and a carbon-based patch. However, NASA admits it will not have a failsafe method ready by launch day. But this doesn't concern the mission's commander.
"It's time for us to get back into space. Do you really want to delay the mission another six months or another year to really perfect the repair techniques? That's the question," says Eileen Collins.
Getting the shuttle back into space is critical for the International Space Station, which needs the shuttle to deliver badly needed supplies including a new gyroscope. Discovery astronauts Stephen Robinson and Soichi Noguchi spent more than five hours this week rehearsing the gyroscope replacement. Two other space walks during Discovery's mission will test shuttle repair techniques.
But these are unproven. If there is serious damage on Discovery, the seven-member crew will remain at the space station until the space shuttle Atlantis can be launched to rescue them.