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Foam and Other Factors—Shuttle Return to Flight

“STS-114 Will Be the Safest Mission Ever!” Says Boeing Shuttle Operations Head

By Steve Bartlett

Ex-astronaut Stephen Oswald, the head of Space Shuttle operations at Boeing, described the preparations for the next shuttle mission in his talk “Return to Flight” on April 20. OASIS members were invited to attend the wide-ranging lecture, sponsored by the Los Angeles chapter of the American Institute of Aeronautics and Astronautics.

Oswald, a veteran of three Shuttle missions with a total of thirty-three days in orbit, told the audience about the changes to the Shuttle system to prevent a repeat of the events of STS-107 in February 2003. On that flight, seven astronauts died during the re-entry of Orbiter Columbia. Subsequent investigation revealed that a piece of insulating foam came loose during flight at high speed. The foam hit the leading edge of one of Columbia’s wings, making a large hole in the thermal protection system. This hole allowed hot gases to enter the wing, leading to the breakup of the Shuttle.

NASA file photo of Stephen Oswald in his astronaut days.

“After the flight, everyone said ‘It was the foam!’ But we all missed it,” stated Oswald. “STS-107 (Columbia) fundamentally changed the direction of human spaceflight. . .It caused the Shuttle fleet to be grounded, put the assembly of the International Space Station (ISS) on hold, and caused the ISS crew to be reduced to two.” He believes that it also led to the President announcing his Space Exploration vision, wherein the Shuttle would be retired in 2010 after ISS completion and space resources would be directed toward exploring and settling the Moon and Mars.

A special government task force investigating the failure of Columbia identified a number of changes that would be required before they considered the Shuttle fleet ready to fly again. Oswald discussed how NASA and United Space Alliance (USA), the Boeing and Lockheed Martin joint venture responsible for operating the Shuttle fleet, has spent the past two years modifying the Shuttle system and launch operations in response to the task force's recommendations. These changes fall into the general categories of damage prevention; in-flight inspection and correction; younger engineers, commented on the capabilities of the Russians, and discussed some of the problems that have cropped up on the ISS. These problems include failures of two of the four Control Moment Gyroscopes used to stabilize the station, balky oxygen-generating equipment (the problem is apparently caused because the equipment needs more power than the Station currently has available), and failed lights.

While this system has not yet been qualified for use on-orbit, it is available in the event of a dire emergency.

The post-Columbia changes to the Shuttle system to accommodate safe haven/safe return focus on flight operations. All Shuttle missions from this point forward will fly to the ISS. This will allow the Station to be used as a lifeboat if damage to the Orbiter prevents it from safely returning to Earth. In that scenario, the Shuttle crew would abandon the Orbiter and move onto the Station until another Shuttle could be sent up to rescue them. To support this ability, a second Shuttle will be prepped in the Vehicle Assembly Building for rollout to the pad in the event of a problem.

United Space Alliance personnel have developed new analytical tools to assess the risks associated with each mission, including software to assess the effects of impacts, aerodynamics, and other processes in flight. “A ‘Golden BB’ hit us last time in a vulnerable location,” stated Oswald, “causing severe damage to Columbia. As a result, we’re ‘fighting the last war’ in trying to solve a problem we’d never seen before.”

The Shuttle Discovery is currently on the launch pad and nearly ready to fly STS-114. The mission will fly to ISS, dock, and offload supplies and equipment from the European-built logistics module. The logistics module will then be loaded up with experimental samples, discarded equipment, packing materials, dirty laundry, garbage, and other waste materials that are currently clogging up the Station.

According to Oswald there will be nine people in space during STS-114: seven aboard the Shuttle and two aboard ISS. If there is problem with the Shuttle thermal protection system, the crew will take refuge aboard the ISS. Three crew members can return to Earth aboard the Soyuz currently docked there.

(At the time of the talk, the projected launch date was May 22. This was subsequently pushed back to July due to concerns about foam attachment to the Space Shuttle External Tank following a close inspection of the tank. This tank was replaced.)

There are three Orbiters left (Discovery, Atlantis, and Endeavour) and these will be used for the 28 flights needed to complete ISS assembly by 2010. The next manned launch system, the Crew Exploration Vehicle (CEV), isn't scheduled to fly until 2014. The CEV will perform a number of Earth orbiting missions prior to its use on manned lunar missions in 2018. What will happen between 2010 and 2014 is unclear.

“The challenge is to transition from what we have today (i.e., the Shuttle system) to the launch system of 2018,” said Oswald. “How do we build a new system while we're still flying the old stuff and keep within NASA’s $16 billion budget?”

Regarding the astronauts’ attitudes about flying the Shuttle, Oswald said, “Folks who’ve flown more are less eager to go. Those who haven't flown are more eager.” He said that he’d gladly go again himself but hates the two years of training required for each mission.

With some sadness, he said, “The Shuttle needs to be retired because it's more fragile than we'd like. When we retire the Shuttle, we won't have another vehicle with comparable capability for about 100 years. It’s a really remarkable vehicle.”

Oswald also gave advice for younger engineers, commented on the capabilities of the Russians, and discussed some of the problems that have cropped up on the ISS. These problems include failures of two of the four Control Moment Gyroscopes used to stabilize the station, balky oxygen-generating equipment (the problem is apparently caused because the equipment needs more power than the Station currently has available), and failed lights.

Regarding the ISS, he noted that it is “an invaluable testbed to understand how to live and work for long periods of time in space.” He said that there are no plans at the moment for a new ISS crew return vehicle. The Russian-built Soyuz will continue to be used for that role. “In retrospect,” Oswald said, “canceling the X-38 (a proposed Station crew return vehicle that was terminated due to budgetary pressures) was probably pretty stupid.”