It's still uncertain when the space shuttle Discovery will actually be launched. NASA engineers made an in-depth review of the space shuttle Discovery's current state and stated that they need more time to get more data and more testing to finally launch the STS-119 mission to the International Space Station. 

Bill Gerstenmaier, associate administrator for Space Operations at NASA Headquarters in Washington, who chaired Friday's Flight Readiness Review, said, "We need to complete more work to have a better understanding before flying. We were not driven by schedule pressure and did the right thing. When we fly, we want to do so with full confidence."

According to the U. S. media, NASA engineers are still working to fix some issues associated with flow control valves on shuttle, which have been responsible for the recent delays in the space shuttle's launch, and thus the agency is still tentative about the space shuttle's launch, which could be delayed until mid-March or early April. 

NASA scientists reported that the 3 valves are very important because they maintain the flow hydrogen gas from each of the shuttle's main engines to its 15-story external tank. These valves help the tank to maintain proper pressure as liquid hydrogen propellant is burned during the 8.5-minute climb to orbit; if pressure surges too high or drops too low, or if a broken valve punctures the gas line, the results could be deadly.