Also Pushes Off ISS Repositioning Due To Glitches

During a review of space shuttle Discovery's readiness for flight, NASA managers decided Tuesday to plan a launch no earlier than February 19 -- one week later than original targets.

The new planning date is pending additional analysis and particle impact testing associated with a flow control valve in the shuttle's main engines. The valve is one of three that channels gaseous hydrogen from the engines to the external fuel tank.

NASA found one of those valves damaged in Endeavour after that shuttle's mission in November. As a precaution, Discovery's valves were removed, inspected and reinstalled. It's not clear yet what the nature of the problem is.

The Space Shuttle Program will convene a meeting on February 10 to assess the analysis. On February 12, NASA managers and contractors will continue the flight readiness review, which began Tuesday, to address the flow control valve issue and to select an official launch date.

Discovery's STS-119 mission to the International Space Station will deliver the last set of solar arrays needed to supply electricity to support a full crew complement onboard the station. The first six-person Expedition to the ISS is slated to be in place later this year.

NASA also disclosed Tuesday a planned repositioning of the ISS has been put off until March, after problems arose during a similar exercise last month. Russian engineers sent commands for the rockets on the Zvezda service module to fire, to place the station in a higher orbit in anticipation of a February resupply mission... but those commands contained errors, which resulted in the rockets cutting off suddenly.

USA Today reports the resulting jolt to the station was outside normal parameters, and may have caused structural damage to the station. While the station was designed to handle higher-than-expected structural loads, NASA is now conducting an analysis to determine whether the incident may have "eaten into that margin," according to NASA spokesman Kelly Humphries.

Due to the station's low orbital position, repositioning rocket burns are used regularly to lift the station further from the pull of Earth's gravity.

FMI: www.nasa.gov