NASA Safety, Engineering Leaders Say Discovery Crew Will Be Safe
Two key NASA leaders said in a new statement that the crew set to ride the Space Shuttle Discovery on a July 1 launch will be able to return safely, after the leaders earlier had expressed concerns about critical safety issues on the shuttle system and recommended against the impending launch.
Bryan O’Connor, NASA chief safety and mission assurance office, and Chris Scolese, chief engineer, issued the new statement.
Separately, in a news conference, O’Connor said he is concerned that there is “delamination” leaving cracks in insulating foam applied to the external tank of the shuttle system.
That means that chances are greater than earlier thought for large chunks of foam to break off during the ascent flight, forming potential missiles that might damage the Discovery orbiter extensively.
This problem, O’Connor said, poses “unacceptable risk” to the orbiter and its chances that it will arrive in orbit without harm, able to survive the heat of a later reentry flight.
Bill Gerstenmaier, associate NASA administrator for space operations, said at the news conference that such views are part of “a very open discussion,” adding that it permitted NASA leaders to “make a really informed, intelligent decision” to go ahead with the Discovery launch.
Despite the misgivings of O’Connor and Scolese, “we are really ready to go fly” in the Discovery mission to the International Space Station, Gerstenmaier said.
Both Gersetenmaier and O’Connor see a solution being devised by yearend, or something like that time frame, for the problem of foam breaking loose to imperil orbiters.
Earlier, O’Connor and Scolese had expressed concern that insulating foam might break off from a component on the external tank that is attached to the shuttle, called an ice frost ramp. O’Connor and Scolese accordingly recommended at that time that Discovery not fly until new safety steps might be taken.
In documents certifying that Discovery is properly ready for flight, Scolese instead wrote that “I remain no go based on [a potential for] loss of vehicle.” At the same time, he added that “for this mission, I have no intention to appeal the decision … ” to fly.
O’Connor wrote, “I am no go based on loss of vehicle risk (ice frost ramps).” He added, however, that “I have no intention to appeal [the NASA decision to fly with] risk acceptance and concur with proceeding with mission.”
NASA leaders, including administrator Michael Griffin, rejected those no-fly recommendations and authorized the Discovery launch, set for Saturday, saying that safety moves have made a flight an acceptable risk.
This would be the second space shuttle mission since Space Shuttle Columbia was damaged during ascent in 2003, and the damage caused the loss of the shuttle and crew of seven during reentry.
A chunk of insulating foam broke off from the external tank and struck the leading edge of the wing on Columbia, creating a hole in the heat shield, damage that permitted superheated gases to enter the wing. That in turn caused structural failure and loss of the shuttle and crew.
During the first post-Columbia flight, when Discovery went into orbit last year, a large chunk of foam also broke loose, but no severe damage resulted.
Since the 2003 disaster, improvements have been made, including removal of substantial amounts of foam applied to the tank on later flights. But O’Connor and Scolese stated in review meetings that they still see a risk of damage caused by foam breaking off and hitting the shuttle orbiter vehicle.
In their new statement, O’Connor and Scolese clarify that, despite their reservations that insulating foam could break off, they still are confident that the crew will be safe.
“Crew safety is our first and most important concern,” they said. “We believe that our crew can safely return from this mission” launching July 1.
This doesn’t mean, the two men made clear, that they have abandoned their earlier-expressed worries.
“We both feel that there remain issues with the orbiter,” they said, in that “there is the potential that foam may come off at time of launch.
“That’s why we feel we should redesign the ice/frost ramp before we fly this mission.”
But while there is a risk of foam loss and damage to Discovery, there is no risk of loss of the crew, the officials said.
“We do not feel … that these issues are a threat to safe return of the crew,” O’Connor and Scolese stated.
“We have openly discussed our position in the Flight Readiness Review–open communication is how we work at NASA,” they continued. “The Flight Readiness Review board and [NASA Administrator Mike Griffin] have heard all the different engineering positions, including ours, and have made an informed decision and the agency is accepting this risk with its eyes wide open.”
The statement, on its face, might raise a question: how can O’Connor and Scolese say there is a danger of damage to Discovery from foam breaking off the ice frost ramp, and yet at the same time there is no danger to the crew?
It works out this way:
If foam breaks loose, and NASA leaders widely agree there may be fissures in the foam that could lead to chunks flying off, and the foam damages Discovery, the damage would be detected before reentry.
Once Discovery attains orbit and achieves rendezvous with the International Space Station (ISS), robotic arms will snake out and enable a minute, repeated inspection of the shuttle, especially the nose and leading edges of the wings and tail. Those are the areas that become white hot during reentry as the shuttle streaks earthward during reentry.
If chunks of loose foam damage Discovery during its ascent, that would be detected during the inspection of the shuttle while it is docked with the ISS.
Then, if potentially crippling damage is found, one of two things will happen: crew members will perform an extra vehicular activity, or EVA, and repair the shuttle during the spacewalk, or the damaged shuttle will be left in space for possible repair later.
In no event will the crew attempt to fly a damaged shuttle through reentry and return to Earth.
Instead, if Discovery is damaged irreparably, the crew will use the ISS as a safe haven, and then return to Earth on a sound spaceship.
This is a point that Griffin made in a media briefing announcing the July 1 launch date for Discovery.
And O’Connor, in the news conference, made a similar point. “The crew does have another option [to] stay on the space station,” he said.
Therefore, while there is a dispute on whether the shuttle faces an unacceptable risk of crippling damage, there is no dispute that the crew faces an unacceptable risk of harm, O’Connor said. Rather, in a review meeting to examine the upcoming Discovery mission, “everybody agreed that the [risk of] loss of crew on this mission is acceptable.”
Scolese noted that if Discovery is damaged significantly, and the Discovery crew must use the ISS as a safe haven, they could stay there for 80 to 82 days while NASA experts divined just how and why the damage occurred, and devised a solution for it.
Further, Scolese noted, a resupply mission to the ISS, perhaps provided by a Russian Progress space shuttle, would extend further the number of days the Discovery crew could remain camped out in the ISS.
That said, O’Connor observed that this wouldn’t be an ideal situation. “Putting nine people onto the space station [creates] real stress,” he said. Still, this is far preferable to a fatally flawed Discovery attempting reentry, resulting in “the loss of the vehicle,” he added.
Viewing the alternatives of discomfort for a crew in a cramped ISS safe haven, versus the horror of an orbiter burning up in the atmosphere during reentry, is what makes the difference between acceptable and unacceptable risk, O’Connor said.
Officials are hoping that Discovery isn’t damaged in the launch and ascent July 1, and that there are no other major complications.
There is relatively little time after the Discovery launch before the next shuttle mission, STS-115, when Space Shuttle Atlantis blasts off Aug. 28.
Some have wondered whether, in event of damage to Discovery during its launch, NASA might use Atlantis as a lifeboat to bring back the Discovery crew from the ISS.
One question in the news conference was this: what happens if Discovery suffers major damage in ascending to orbit, so that it can’t return to Earth, and then a rescue mission by Atlantis also suffers major damage to the orbiter? That would leave the ISS crew and two space shuttle crews crammed into the ISS.
But NASA sees such a series of calamities as almost improbable and “extremely remote,” Gerstenmaier said.