NASA officials are pressing ahead with the launch of the Space Shuttle Discovery on July 1, despite objections from its chief engineer and safety head.
The issue is the insulating foam around the “ice/frost ramps” that hold pressurization lines above the shuttle’s giant external tank. On the previous 114 shuttle missions, NASA’s records show several instances in which foam came off of the ice/frost ramps.
The concern is a “golden bullet” scenario where a piece of foam dislodges and has enough mass and speed to damage the shuttle. It’s similar to the scenario in which a large piece of foam from a different portion of the shuttle’s tank fell off, slammed into the wing and doomed the shuttle Columbia in 2003.
Chief of Safety and Mission Assurance Bryan O’Connor, a former astronaut, explained why he recommended a “no-go” but didn’t object to being overruled.
“I think we’re just barely into the unacceptable risk area,” he said. “I think it’s unacceptable to the program to go fly in this condition, but I also believe if it’s elevated to the right authority, an administrator who looks at it and with his understanding and his position in the agency who can accept it, then I felt like I was not going to lie down in the flame trench or throw my badge down.”
In this case, that authority is NASA Administrator Michael Griffin.
“If we are unlucky and we have a debris event on ascent, it will not impede the ascent,” Mr. Griffin said. “The crew will arrive safely on orbit and then we will begin to look at our options. … We have elected to take the risk; we do not believe we are risking crew.”
Mr. Griffin justified his actions on the basis that the crew could repair the damage or remain at the International Space Station until a rescue mission can be mounted.
Constant shuttle delays, he said, also add pressure because of the 2009-10 time frame to complete the assembly of the International Space Station before the shuttle is retired.
Astronaut Don Pettit was one of the members of a “tiger team” that examined why large pieces of foam fell off of Discovery on its most recent mission a year ago.
“We have more cameras than ever on the outside of the orbiter and the external tank and we will be able to get a good gander at what’s happening,” Mr. Pettit said. “One major piece of data that we’ve had very little information in the past is when the foam comes off. If it comes off later in flight the potential for doing damage is a lot less.”
The commander for the upcoming shuttle mission is Air Force Col. Steve Lindsey, 45. He supports the decision to go ahead with the mission.
“I think one of the things, though, that the managers especially wanted to do was make sure that everybody in the program recognizes [the ice/frost ramp] is our top risk,” he said. “They’re kind of [breaking it out] to separate it from all the other risks that are out there to make sure everybody’s aware of that.”