CAPE CANAVERAL, Fla. -- NASA
mission managers are eyeing the weather for Friday’s planned landing of
the space shuttle Discovery
while awaiting the results from a second look at the orbiter’s heat
shield.
“We’re assuming the
vehicle is in a go condition for landing unless somebody illuminates an issue
out of that data,” Phil Engelauf, NASA’s
mission operations representative for Discovery’s STS-116
flight, said of today’s heat
shield inspection during an
afternoon status briefing. “But the assumption is everything is fine and
we have no reason to suspect anything other than that for the vehicle as of
this time.”
Meanwhile, mission managers and
flight controllers are going over options for Discovery’s return to
Earth, currently set for no earlier than 3:56 p.m. EST (1856 GMT) on Friday.
Discovery’s STS-116 astronaut crew, commanded by
veteran spaceflyer Mark Polansky, is due to land here at NASA’s Kennedy Space Center
to conclude a successful 13-day mission that continued assembly of the International Space
Station (ISS), but only if the weather cooperates.
“If we have
‘Go’ weather at Kennedy, than we’ll certainly try to get into
Kennedy,” Engelauf said. “If we have
questionable weather at Kennedy and better weather at one of the other sites,
then we’ll probably end up going to one of the other sites.”
Current weather forecasts for
NASA’s Shuttle Landing Facility here predict low clouds and a hint of
rain that could prevent Discovery’s planned touchdown at KSC, NASA
officials said.
KSC is NASA’s preferred
orbiter landing strip since it allows shuttle engineers to turn the vehicle
around for its next flight at the space agency’s launch site more
quickly.
The space agency is also
tracking weather at the shuttle’s alternate landing sites at Edwards Air
Force Base in California’s Mojave
Desert, where high cross winds are expected, and the White
Sands Space
Harbor in New Mexico.
“Our intent will be to
land somewhere on Friday,” Engelauf said.
If a KSC landing is unavailable,
NASA mission managers will shift to either Edwards or White Sands depending on
the weather at each site. In the past, the White Sands site has been viewed as
last resort due to a dearth of orbiter turnaround facilities at the New Mexico installation.
A landing at Edwards, which like
KSC contains the required infrastructure to land an
orbiter and ferry it back to NASA’s Florida spaceport, typically adds one extra
week and added cost of about $1.7 million to once more ready a NASA shuttle for
flight.
With a White Sands landing at Northrup Strip, returning Discovery back to KSC for
turnaround processing could take up to 45 days, NASA officials said.
“It will be longer coming
back from there,” Engelauf said.
NASA landed a space shuttle once
at the White Sands facility in 1982 during the STS-3 mission aboard Columbia, but the orbiter
suffered contamination from the landing strip's gypsum surface, the space
agency said.
Engelauf added that some initial infrastructure to handle
Discovery’s post-landing power and purging needs will be flown out to the
White Sands site in preparation for the site’s potential use.
Discovery’s landing
schedule woes stem from the loss of one of two extra days NASA traditionally
adds to each shuttle flight to ensure the orbiter has enough supplies to
maintain its crew until landing.
Discovery launched
Dec. 9 on a planned 12-day
mission with two days in reserve in case of a systems glitch or poor
landing weather. But mission managers sacrificed one of those spare days Monday
to stage
an unplanned spacewalk by STS-116 astronauts Robert
Curbeam and Christer Fuglesang to wrangle
an unruly
ISS solar array into its storage boxes.
NASA flight rules stipulate that
the space agency land somewhere Friday if possible to protect its remaining
flight day in the event of an unforeseen systems glitch, though the
orbiter’s supplies will only last through Saturday, Engelauf
said.
Polansky and his STS-116 crewmates are wrapping up
successful flight to the ISS, where they installed
a new piece of the orbital laboratory, rewired
its power grid and performed an astronaut
swap for the outpost’s Expedition 14 crew.
The astronauts are due to launch
a pair of microsatellites from Discovery’s
payload bay, along with a third set on Thursday, before
returning to Earth on Dec. 22.
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