HOUSTON - NASA shuttle officials are withholding
a final judgment on whether the Discovery orbiter's heat shield is safe for the
return trip until after a team of analysts completes a meticulous survey of the
up-close images taken during a Friday inspection.
"They may
tell me tomorrow, they may tell me Sunday," said John Shannon, NASA's deputy
shuttle program manager, of when analysts expect to complete their work. "I'll
get it when I get it."
On
Thursday, Shannon expressed hope Discovery's heat shield would be cleared for
reentry by the end of this weekend.
Earlier
today, STS-121 mission specialists Stephanie
Wilson, Lisa
Nowak and shuttle pilot Mark
Kelly relayed home a batch of high-resolution images aimed at cementing the
case. The imagery featured six key areas that engineers requested after going
through photographs of Discovery's heat shield snapped from the International
Space Station (ISS) during Thursday's
docking.
Of those
six areas, several appear to have been settled - among them a frayed bit of
fabric from a so-called "tadpole" gap filler just aft of Discovery's nose
landing gear and a small white blotch on the orbiter's nose - though NASA
orbiter project manager Steve Poulos said final imagery analysis is still
pending on both items.
Poulos said
a bit more scrutiny is required over a protruding gap filler peeking up perhaps
an inch above the surrounding heat-resistant belly tiles near the orbiter's
wing flap. The protrusion is near door that covers an external tank connection
and could lead to higher than expected heating aft of the gap filler than
reentry. Analysis of both the thermal and structural effects of such heating is
anticipated to be complete by Sunday, he added.
Several images
of sites along the middle of Discovery's starboard - or right - wing leading
edge have caught the eye of analysts as well, since they show dark marks on the
heat-resistant reinforced carbon carbon panels that experience some of the
highest temperatures - up to 2,960 degrees Fahrenheit - seen during reentry.
"Once we get
the high fidelity imagery, it's either not an issue or something we'll need to
be worried about," Poulos said if the RCC panel areas. "I think we'll have that
information here this evening."
Aside from
the six suspect areas, Poulos said Discovery is in ship shape.
"Orbiter
systems couldn't be functioning better," Poulos said. "We are really not
tracking anything significant, hardly anything at all to be honest."
Discovery
is flying NASA's second shuttle flight since the 2003 Columbia accident.
Recently extended one day to a 13-day mission, the STS-121 spaceflight will
resupply the ISS, leave a third crewmember aboard, make repairs to the outpost
and test shuttle inspection and repair methods.
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