NASA has approved a new mission for Discovery's STS-119 to the International Space Station after reviewing its potentially hazardous hydrogen flow control valve.

The shuttle is scheduled to blast off from Kennedy Space Center at 9:20 p.m. EST on Wednesday, March 11.

Discovery's launch was postponed after its hydrogen flow control valve was damaged during Endeavour's November 2008 STS-126 mission.

NASA explains: The three flow control valves, one for each space shuttle main engine, channel gaseous hydrogen from the engines through the main propulsion system and back to the external fuel tank. This flow regulation maintains the tank's structural integrity and delivers liquid hydrogen to the engines at the correct pressure.

The problem was a cracked component, but NASA says that Discovery's trio of valves have been removed, examined and cleared of crack indications.

Space Shuttle Program manager John Shannon said the National Aeronautics and Space Administration now had definitive data to prove that the upcoming launch was safe, according to AFP.

It feels good to be here with a firm launch date, said Mike Leinbach, the space shuttle launch director. I saw a lot of people after the meeting and the mood is really upbeat.

During the 14-day mission, four spacewalks are planned - principally to install the new solar kit.