NASA Gives Final "Go" for Space Shuttle Discovery July 1 Launch
21 June 2006
Dissenters say foam-loss should be addressed, but poses no danger to safe return
Washington -- NASA senior managers have cleared the space shuttle Discovery for a July 1 flight to the International Space Station, even though engineers still expect small pieces of insulating foam to come off the external tank during launch.
They announced the decision at a press conference June 17 after a two-day flight readiness review, a traditional meeting in which top NASA managers and engineers set launch dates; determine whether the shuttle's complex array of equipment, support systems and procedures are ready for flight; and assess risks associated with the mission.
The review, said NASA Administrator Michael Griffin, "was spirited and one of the most open yet non-adversarial meetings I've seen since returning to NASA."
Since the July 2005 launch of Discovery, when a large piece of insulating foam came off the external tank, NASA engineers have been working to eliminate a recurrence of this event during future launches. Large pieces of flying foam could damage the orbiter’s heat-shielding tiles during the spacecraft’s ascent to orbit. (See related article.)
A high-resolution camera that was added to the shuttle after the loss of space shuttle Columbia and its seven-member crew in 2003 spotted the foam break off during the 2005 launch. The Columbia accident was caused on re-entry to Earth’s atmosphere by damage resulting from external-tank foam striking the orbiter during launch.
DISSENTING VIEWS
Two days after the flight readiness review, June 19, NASA Chief Safety and Mission Assurance Officer Bryan O'Connor and Chief Engineer Chris Scolese issued a statement on the decision to launch Discovery in July despite reservations.
Although they believe the crew can return safely from the STS-121 mission, they said, “we both feel that there remain issues with the orbiter – there is the potential that foam may come off at time of launch.”
That, they wrote, is “why we feel we should redesign the ice/frost ramp before we fly this mission. We do not feel, however, that these issues are a threat to safe return of the crew.”
To prevent foam break-offs in the future, NASA engineers have removed 15.4 kilograms of foam from the external tank’s protuberance air load ramp, a structure that prevents unsteady airflow under tank cable trays and pressurization lines. During the 2005 launch, foam was shed from this area.
The next largest sources of foam loss are structures called ice/frost ramps that are made of insulation foam covering 34 brackets that connect piping to the surface of the orange external fuel tank. Each bracket is covered with 0.7 to 1.5 kilograms of foam. The ramps are a potential source of foam loss that could damage the shuttle, but the flight readiness review board decided the current design is not risky enough to delay the upcoming mission. In the meantime, design improvements for later flights are under way.
Eliminating the ice/frost ramp foam, said Space Shuttle Program Manager Wayne Hale, is next on NASA’s agenda.
"We were really careful to evaluate everything as thoroughly as we could," said Associate Administrator for Space Operations Bill Gerstenmaier, who chaired the flight readiness review. "But the review of the ice/frost ramp was one of the most vigorously discussed."
Griffin said NASA will fly shuttles with the ice/frost ramps for a very small number of flights until the redesign is complete.
“The question is can we fly a few times with this ice/frost ramp without probably incurring a hazard,” Griffin said, “and based on the data I have seen, I believe that we can.”
SHUTTLE LAUNCHES
The Discovery launch countdown begins June 28. Commander Steve Lindsey and six crewmates are scheduled to lift off July 1 to begin a 12-day mission, designated STS-121. The mission launch window extends to July 19.
Discovery's crew will test new hardware and techniques to improve shuttle safety, deliver supplies, make repairs and transport a third crew member to the space station.
Joining Lindsey aboard Discovery will be pilot Mark Kelly, mission specialists Mike Fossum, Piers Sellers, Lisa Nowak and Stephanie Wilson.
European Space Agency (ESA) astronaut Thomas Reiter will launch on Discovery and stay on the station for several months.
Already aboard the station, Expedition 13 Commander Pavel Vinogradov, a Russian Federal Space Agency cosmonaut, and flight engineer and NASA station science officer Jeff Williams will greet Discovery and its crew.
Vinogradov and Williams began their six-month mission on the station March 31. (See related article.)
The next shuttle flight, STS-120, will launch an Italian-built U.S. module for the space station. U.S. Air Force Colonel Pamela Melroy will command the mission. The launch date for STS-120 has not yet been set.
Melroy, a veteran shuttle pilot, is the second woman to command a shuttle. Marine Corps Colonel George Zamka will serve as pilot.
The flight's mission specialists will be Scott Parazynski, U.S. Army Colonel Douglas Wheelock, U.S. Navy Captain Michael Foreman and Paolo Nespoli, an ESA astronaut from Italy. Zamka, Wheelock, Foreman and Nespoli will be making their first spaceflights.
Information about the STS-121 mission and astronaut biographies are available at the NASA Web site.
(The Washington File is a product of the Bureau of International Information Programs, U.S. Department of State. Web site: http://usinfo.state.gov)
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