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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