NASA’s second space shuttle flight since the Columbia tragedy will launch as planned on July 1, the space agency said Saturday, after two days of intense debate that included dissent from two senior officials.
“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 Kennedy Space Center. “We’ve decided that we are.”
Discovery's first opportunity for launch will come on July 1 at 3:48:15 p.m. ET.
Griffin said Saturday's decision followed 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, serving as insulation for brackets that connect a cable tray and pressurization lines.
“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.”
NASA weighs risks
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 re-enter 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 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 — will serve as a test flight for shuttle fuel tank changes, orbiter inspection and repair techniques. It will also deliver vital supplies to the space station.
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 (455-gram) piece of foam insulation fell from a protective ramp on 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.
Over the past year, engineers have redesigned the shuttle's tank to eliminate the piece of foam that caused the problem during last year's flight.
The STS-121 crew will launch what's expected to be a 13-day mission to the space station, with two planned spacewalks — and a third spacewalk if shuttle resources permit.
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 station's crew size back up to three astronauts for the first time since the Columbia accident. The German native will also be the first long-term station crew member to represent a country other than the United States or Russia.