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Space Shuttle Discovery on Schedule for July Launch

01 June 2006

NASA official expects three total shuttle launches in 2006

By Cheryl Pellerin
Washington File Staff Writer

Washington – The space shuttle Discovery is on schedule for a July launch, and NASA officials expect to launch two more flights in 2006, the Atlantis later this summer and a third flight now scheduled for December.

In a May 31 press briefing from the Kennedy Space Center in Florida, where Discovery was moved to the launch pad May 19, Space Shuttle Program Manager Wayne Hale and Space Shuttle Launch Director Mike Leinbach discussed the status of the space shuttle program and the next mission, STS-121.

NASA engineers have been working to eliminate the possibility that large pieces of insulating foam will come off the external tank, potentially damaging the orbiter’s heat-shielding tiles during the spacecraft’s ascent to orbit.

A large piece of the foam flew off Discovery’s external fuel tank during the July 26, 2005, launch. The foam -- 61 to 84 centimeters long, 25 to 33 centimeters wide and 6 to 20 centimeters thick -- was seen by a high-resolution camera added to the shuttle after the loss of Columbia in 2003. (See related article.)

The Columbia accident was caused by damage resulting from external-tank foam striking the orbiter during launch.

The briefing came after a meeting at Kennedy Space Center of more than 100 NASA engineers during a debris verification review of improvements made since the last shuttle flight (STS-114) in 2005.

“Today in our review we did come to the conclusion that we have an acceptable risk posture to go fly from the debris standpoint,” Hale said. “That is a major milestone.”

ELIMINATING HAZARDS

Although small pieces of insulating foam will still come off the external tank during launch, Hale said, “what we have done in a very systematic manner is eliminate the largest hazards.”

So far, the engineers have removed 15.4 kilograms of foam from the external tank to reduce potential damage to the orbiter’s heat-shielding tiles from flying pieces of foam.

The reduction in foam was the result of removing the protuberance air load ramp, a structure that prevents unsteady airflow under tank cable trays and pressurization lines. During the last launch, foam was shed from this area.

A special set of sensors has been added to the external tank and six new cameras have been added to the solid rocket boosters to allow NASA engineers to monitor vehicle performance during ascent.

The next largest source of foam loss, Hale said, is the foam on the 34 brackets that connect piping to the tank’s surface. Each bracket is covered with 0.7 to 1.5kilograms of foam, totaling another 13.6 kilograms of foam. Eliminating that foam, Hale said, is next on the agenda.

Engineering teams at Marshall Space Flight Center in Alabama and the Michoud External Tank Facility in Louisiana are working to redesign the brackets to eliminate the need for insulating foam and to make sure no ice forms on the hardware.

“Subsequent to that,” Hale said, “we will work on the next area of concern, and eliminate systematically ... the sources of foam coming off the tank, so that the very last tank we fly I think will be the very safest tank that we’ll ever fly, one causing the least source of debris.”

RETURN TO FLIGHT

Discovery's launch is targeted for July 1 in a launch window that extends to July 19. 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 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.

On June 7, Hale said, the External Tank Design Certification Review will determine whether the structure of the modified external tank is still safe to fly. The Flight Readiness Review, to be held June 16 and 17, will make sure all problems are solved.

“I foresee no ‘show stoppers,’” Hale said, “but there is a lot of work that’s got to be done in the next month to be sure that we’re safe to go fly.”

Additional information about space shuttle missions is 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)