CAPE
CANAVERAL, Fla. – NASA's second space shuttle flight since the Columbia tragedy will launch as
planned on July 1 after two days of intense debate that included dissent from
two senior officials, the space agency said Saturday.
"There were
many different viewpoints on the issue of whether we are ready to fly or not,"
NASA chief Michael Griffin told reporters here at the Kennedy Space Center
(KSC). "We've decided that we are."
Discovery
will launch on July 1 at 3:48:15 p.m. EDT (1948:15 GMT).
Griffin
said the decision came after two days of "intensive and spirited exchange"
during a Flight
Readiness Review for NASA's STS-121 shuttle flight aboard the Discovery
orbiter.
Two senior
NASA managers – chief engineer Chris Scolese and Bryan O'Conner, the
associate administrator of Safety and Mission Assurance – did have
concerns over the potential risk of foam debris posed by a number of insulated
ice frost ramps along Discovery's external tank, NASA officials said.
About 34
foam-covered ice frost ramps line the shuttle fuel tank, insulating brackets
that connect a cable tray and pressurization line.
"From their
particular discipline, they felt they wanted their statement to be No-Go,"
William Gerstenmaier, NASA's associate administrator for space operations said.
"But they do not object to us flying and they understand the reasons and the
rationale that we laid out in the review for flight."
That flight
rationale, Griffin added, states that while foam debris damage – such as
that which led to the loss of Columbia – could affect a shuttle's
availability to reenter the Earth's atmosphere, the spacecraft's astronaut crew
could reach the orbit.
NASA's
ability to inspect the spacecraft in orbit, conduct rudimentary repairs, and
even keep shuttle astronauts aboard the International Space Station (ISS) until
a rescue shuttle or Russian Soyuz vehicle can be launched were all factors that
contributed to the positive launch decision, Griffin said.
But the
NASA chief also said that much is riding on Discovery's flight and its safe
return to Earth.
"Leaving
aside the issue of crew, if we were to leave another vehicle...I would be moving
to shut the program down," Griffin said. "I think, at that point, we're done."
A
critical spaceflight
Discovery's
STS-121 mission – commanded by veteran shuttle astronaut Steven
Lindsey – is NASA's final return to flight test to shuttle fuel tank
changes, orbiter inspection and repair techniques, as well as deliver vital
supplies to the ISS.
It's been almost
one year since NASA's first post-Columbia accident mission, STS-114 also aboard Discovery, took
flight. The STS-121 crew has filled that time with additional training
while shuttle engineers developed new external
tank foam modifications and subsequent tests to prevent large chunks from detaching
during launch.
A one-pound
(0.4-kilogram) piece of foam insulation fell
from a protective ramp – since removed
– from Discovery's external tank during the STS-114 launch in July 2005.
That chunk of launch debris did not strike Discovery, but a similar foam
shedding event did occur during the Columbia orbiter's 2003 launch, piercing
the spacecraft's heat shield and ultimately leading to its destruction and loss
of seven astronauts.
The STS-121
crew will launch on a 12-day mission to the ISS, with two planned spacewalks
– and a third if shuttle resources permit – on tap for their
spaceflight.
The
spaceflight will also deliver European Space Agency astronaut Thomas Reiter to
the station to join the orbital outpost's Expedition 13 crew.
Reiter will
raise the ISS crew size back up to three astronauts for the first time since
the Columbia accident, and is the first long-term ISS crewmember to be from a
country other than the U.S. or Russia.
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