July 4th, 2006 12:57 EST
NASA's Discovery First Shuttle To Launch on July 4 By Cheryl Pellerin
Washington -- Despite two launch attempts cancelled due to bad weather and dissenting views among NASA officials about whether the condition of the external tank's insulating foam allowed for a safe launch, Discovery blasted into the Florida sky July 4, the second shuttle in space since the Columbia accident in 2003.
In what NASA described as "a spectacular display of sound and light befitting of Independence Day," the space shuttle Discovery lifted off from Kennedy Space Center’s Launch Pad 39B at 2:37 p.m. EDT (1837 GMT) to begin its high-speed chase to intercept the International Space Station.
Discovery’s seven astronauts enjoyed "a smooth ride to orbit," according to NASA, after a launch sequence that proceeded without delay in spite of concerns raised the previous day regarding a crack in a piece of insulating foam.
The crew’s mission includes delivering equipment, supplies and an additional crewmember to the station. While docked, the crew will test new equipment and procedures to improve shuttle safety and make repairs to the station, NASA said.
RETURN TO FLIGHT
Discovery returns to the International Space Station with many improvements, including a redesign of the shuttle external fuel tank's foam insulation, inflight inspection of the shuttle's heat shield, improved imagery during launch, and the ability to launch a shuttle rescue mission if needed, using the space shuttle Atlantis.
This mission, designated STS-121, also will enhance the space station by making a key repair, delivering more than 12,700 kilograms of equipment and supplies and dropping of a third crewmember.
Two spacewalks are planned during Discovery's 12- day mission. If there is enough electrical power, the mission will be extended by one day and a third spacewalk will be added. Shuttle managers hope to make that decision by flight day 6.
As Discovery nears the space station, the shuttle will rotate so the station's crew can photograph its belly to determine whether the shuttle's heat shield, called the thermal protection system, is damaged. This tricky maneuver was first demonstrated in 2005 with the STS-114 mission.
During the mission's spacewalks, astronauts will test the 50-foot boom extension to the robotic arm as a work platform and remove and replace a cable that provides power, command and data and video connections to the station's mobile transporter rail car. The transporter is used to move a platform containing the station's robotic arm along the truss of the complex.
If there is time and electrical power, the astronauts will test techniques for inspecting and repairing the materials that protect the shuttle's nose cone and wing leading edges.
STS-121 will be NASA's most-photographed mission in shuttle history. More than 100 high-definition, digital, video and film cameras will help managers and engineers assess whether debris comes off the external tank during the shuttle's launch.
Four new video cameras have been added to the solid rocket boosters.
Two days after the June 17 flight readiness review, during which NASA managers decided to launch Discovery even though engineers still expected small pieces of insulating foam to come off the external tank during launch, NASA Chief Safety and Mission Assurance Officer Bryan O'Connor and Chief Engineer Chris Scolese issued a statement on the decision to launch despite reservations.
Although saying they believed the crew can return safely from the STS-121 mission, they wrote, "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 added, 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.
"I had spent an awful lot of time on my own studying the issue very carefully," NASA Administrator Michael Griffin said July 2 during a [Fox News Sunday] television interview, "because I knew it was going to be controversial. And my analysis of it convinces me that the chances of damaging the orbiter are quite small, and this is risk worth taking at this time to get us back on track in space."
Even the safety officer and the chief engineer, Griffin added, "agreed that we are not, with this decision, risking crew. The risk is to the vehicle, not the crew, and I felt that it was acceptable to take."
During the 12-day mission, Discovery's crew will test new hardware and techniques to improve shuttle safety, and deliver supplies and make repairs to the station.
Discovery will transport a third crewmember to the station, European Space Agency Astronaut Thomas Reiter. This will be the station’s first three-person crew since the Expedition 6 crew returned to Earth in May 2003.
Without the space shuttle to ferry equipment to the station after the Columbia accident, only two people could be supported onboard until the necessary provisions were in place.
The orbiter will carry the Italian-built multi-purpose logistics module Leonardo, which will carry more than 1.8 metric tons of equipment and supplies.
This will be the fourth trip to the station for Leonardo, the first of three Italian-built modules. Equipment and supplies no longer needed on the station will be moved to Leonardo before it is unberthed on flight day 10 and put back into Discovery's cargo bay for return to Earth.
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 that mission, 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.
Additional information about STS-121 mission is available at the NASA Web site, as is a press release on STS-120.
(The Washington File is a product of the Bureau of International Information Programs, U.S. Department of State. Web site: http://usinfo.state.gov)