The STS-120 crew walks out for launch rehearsal. In the left row are: (from front) pilot George Zamka and mission specialists Stephanie Wilson, Daniel Tani, and Scott Parazynski. In the right row are: (from front) commander Pam Melroy and mission specialists Doug Wheelock and Paolo Nespoli.
Credit: NASA/Kim Shiflett.
Top NASA officials will decide today whether to proceed with the planned launch of the space shuttle Discovery next week or to stand down and replace several heat shield panels lining the orbiter's wings.
Mission managers and engineers are meeting at NASA's Kennedy Space Center (KSC) in Cape Canaveral, Florida in a Flight Readiness Review (FRR) for Discovery's planned Oct. 23 launch toward the International Space Station (ISS).
Among the chief topics under discussion is whether to haul Discovery off its launch pad and replace three of the 44 heat-resistant panels along the orbiter's wing leading edges. NASA's independent Engineering and Safety Center recommended the panels be replaced, which would prompt a lengthy delay for Discovery's planned STS-120 mission, due to slight defects to their exterior coating, the space agency said.
"The decision has obviously not been made," NASA spokesperson Kyle Herring, of the agency's Johnson Space Center, told SPACE.com Monday. "The FRR tomorrow will determine whether we fly as is and pick Oct. 23."
The leading edges of Discovery's wings are each covered with 22 panels of reinforced carbon-carbon (RCC) designed to withstand searing temperatures of up to 3,000 degrees Fahrenheit (1,650 degrees Celsius) as the shuttle reenter's the Earth's atmosphere during landing.
The shuttle has flown at least twice with some of its wing-mounted heat shield panels bearing slight defects in their exterior coating. While post-flight inspections found no change in the defects after each flight, engineers remain baffled at the root cause of the coating loss.
"At this point, the space shuttle program has determined that Discovery's astronauts can safely carry out their mission without having to replace the panels," NASA said in a statement.
Herring said engineers have performed some additional data analysis on the coating loss, the results of which will be presented during today's preflight meeting. NASA managers will also discuss, among other topics, modifications to Discovery's external fuel tank to reduce the amount of foam insulation and debris shedding during liftoff.
NASA has kept a close watch on the health of its space shuttles' heat shields and fuel tank foam insulation since the 2003 loss of the Columbia orbiter and its astronaut crew due heat shield damage from foam debris.
Discovery's STS-120 astronaut crew, commanded by veteran shuttle flyer Pamela Melroy, is slated to launch toward the space station to deliver a vital new node to the orbital laboratory. The node, named Harmony in a student contest, will serve as a connection point for future international laboratories.
The shuttle astronauts also expect to perform five spacewalks and relocate an older solar array segment outside the space station during their planned 14-day mission.
NASA will hold a press briefing no earlier than 3:00 p.m. EDT (1900 GMT) on NASA TV to discuss today's Flight Readiness Review meeting for Discovery's STS-120 shuttle mission.
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