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Discovery goes to pad
As night fell over Kennedy Space Center on May 19, space shuttle Discovery reached launch pad 39B to complete the slow journey from the Vehicle Assembly Building. Discovery will be traveling much faster in a few weeks when it blasts off to the International Space Station.

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Discovery moves to VAB
Perched atop a trailer-like transporter, space shuttle Discovery was moved May 12 from its hangar to the 52-story Vehicle Assembly Building for mating to its external fuel tank and twin solid rocket boosters in preparation for the STS-121 mission.

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Shuttle launch date set despite safety objections
Posted: June 17, 2006

NASA Administrator Mike Griffin, overruling objections from the agency's chief engineer and safety office, cleared the shuttle Discovery for launch July 1 on a mission to service and resupply the international space station. The flight also will clear the way for the resumption of station assembly later this fall and deliver a third full-time crew member to the international outpost.

This is a view inside the Flight Readiness Review that set July 1 as Discovery's official launch date. Credit: NASA-KSC
The objections centered on the risk posed by launching Discovery with foam buildups around brackets on the ship's external tank that are now formally classified as "probable/catastrophic" in NASA's integrated risk matrix. That means it is probable that the so-called ice-frost ramps will shed debris with catastrophic results over the life of the program.

Griffin told reporters today he did not agree with the probable/catastrophic classification and added that even in a worst-case scenario, the astronauts would not be in immediate danger. Because of new cameras and other sensors, any damage would be seen and the crew could either attempt repairs or move aboard the space station to await rescue by another shuttle crew.

Throwing in broader programmatic issues, including a presidential directive to finish the station and retire the shuttle fleet in 2010, Griffin said he decided it made more sense to resume shuttle flights now, with the current ice-frost ramps, and to implement a redesign as soon as possible.

Insisting safety remains his top priority, Griffin left no doubt about the stakes involved. Losing another space shuttle - even if the crew survived - will mean the end of the program.

"If we were to lose another vehicle, I would tell you right now that I would be moving to figure out a way to shut the program down," he said. "I think at that point, we're done. I'm sorry if that sounds too blunt for some, but that's where I am. We're trying to navigate some very difficult waters ... to get the station assembled. I think that's worth doing. I've stated that on multiple occasions, but it's not easy."

Griffin's comments came at the end of a two-day flight readiness review at the Kennedy Space Center where top agency managers and engineers gathered to review Discovery's flight processing. The debate about the classification of the ice-frost ramps in NASA's integrated risk matrix stirred a fair amount of debate. NASA's chief engineer and safety manager both said that if the ice-frost ramps were classified "probable/catastrophic" they were no-go for launch. The majority of those attending the FRR disagreed and voted to proceed with the flight. The final decision was Griffin's.

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Because of the unique nature of this debate, and because of the high stakes involved, here is Griffin's complete answer to a question from CBS News to explain his rationale:

"I'm not concerned with what box in the matrix we're in because that's a matter of terms and definitions," he said. "In point of fact, I don't agree with the way that we categorized that risk as being 'probable.' Because if it's going to be 'probable,' then that means that over some reasonable span of flights I would expect to see evidence of that behavior. We can as statisticians go off and argue about what percentage of the time you expect to see it, but if we say 'probable,' we mean that over some reasonable span of activity we should see it. And I won't at this point refine it further.

"Now, in fact, we have 113 flights (sic) with this vehicle with these ice-frost ramps under our belt. And while we've had two loss of vehicle incidents, they've not been due to ice-frost ramps. So I have a great deal of trouble believing that a statistically sound statement would be to say that this is a 'probable' event to be seen over the next 16 flights. I just have trouble with that.

"Now without regard to the label, getting past the label, the concern then is do we, in fact, think that if we fly this ice-frost ramp the way it is for some very small, not 16, but some very small number of flights, a few, until we have a better design - and let me be the first to lead the parade saying we've got to have a better design, we want to know that it's a better design and we want to take our time with it - so the question is, can we fly a few times with this ice-frost ramp without probably incurring a hazard? And based on the data I have seen, I believe that we can.

"I believe that our models are quite conservative, I believe that our models have a huge variance in them, we really don't know as much about these phenomena as we would like to. Because if we believed our models, we would believe that we had a worse problem than our flight data is showing, which is a red flag to indicate that we don't understand as much as we would like to understand. We need to continue to be hungry, we need to continue to dig out the information the vehicle is telling us. But we need to fly it to dig it out.

"So how do I justify that? With as much uncertainty as we have, I ... certainly would have to think harder about putting a crew on this vehicle if I thought they didn't have the space station safe haven option and the launch-on-need (rescue flight) option and for that matter, if push came to shove, to call up Russian Soyuz spacecraft for rescue. I do not see the situation we're in as being a crew-loss situation.

"If we are unlucky and we have a debris event on ascent, it will not impede the ascent, the crew will arrive safely on orbit and then we will begin to look at our options, whether those include repair, launch on need, extended safe haven on the station, asking our Russian partners for help, maybe some or all of the above. We will have decisions to make, but we will have time to make those decisions. We are not in the situation that we were in with Columbia where we didn't know that we had a problem. We'd know we have a problem, we have elected to take the risk, we do not believe we are risking crew.

"There is a programmatic risk, without doubt. If we have another major incident in launching the space shuttle, I would not wish to continue with the program. We're going to use this flight and the subsequent flights to complete the space station, that's what we want to do with the shuttle, within the next three years we're going to complete the space station. We believe it is possible to do so. But if it is going to be possible to do so, we're going to have to take some programmatic risks because the shuttle will be retired in 2010.

"This president's budget will not carry funding for shuttle vehicles beyond 2010. So if we're going to fly, we need to accept some programmatic risk and get on with it. Again, I'll point out, for me to accept programmatic risk to do this is not the same as accepting a crew risk, which we believe we're not doing."

In shuttle program manager Wayne Hale's view, NASA already is accepting a fair amount of risk based on an earlier decision to remove so-called protuberance air-load - PAL - ramps from the tank in the wake of a major foam shedding incident during Discovery's last flight a year ago.

The PAL ramps were in place to shield external pressurization lines and a critical cable tray from aerodynamic buffeting as the shuttle climbs out of the dense lower atmosphere. The pressurization lines are held in place by 34 brackets that are covered in foam insulation - ice-frost ramps - to prevent potentially dangerous ice formation before launch.

Wind tunnel testing and computer modeling have convinced managers the tank and its external lines and fittings are tough enough to stand up to the stresses of launch without the PAL ramps. But NASA does not yet have a redesign in place for the ice-frost ramps, which now represent the most potentially dangerous concentrations of foam on the tank.

Engineers had hoped to implement a redesign before Discovery's flight, but wind tunnel testing showed the proposed change fared worse than the old design. As a result, Griffin, Hale and other senior agency managers agreed earlier this spring to stick with the old design for the next few shuttle flights while another redesign is perfected.

After an extensive debris verification review May 31, Hale said he agreed the ice-frost ramp foam should be listed in the risk matrix as probable/catastrophic. But he said NASA was justified in pressing ahead with near-term shuttle flights while engineers devise a bracket redesign that eventually will allow them to remove the ice-frost ramp foam altogether. While the IFR foam represents a clear long-term threat, the risk on any given flight is in line with dangers posed by other systems.

Hale said today the "probable/catastrophic" classification reflected his belief "as program manager those issues need to be elevated to senior NASA management for their review and disposition. I believe they are at an unacceptable level for the program manager to take that risk on by himself."

Even so, Hale said he believes the ice-frost ramps are "an acceptable risk" when viewed from a broader agency perspective.

"I recommended to the administrator and (spaceflight chief) Bill Gerstenaier that even though we did rate these very high, I think it is acceptable for a number of reasons to go fly for a limited number of flights while we come up with the redesign," Hale said. "So that's where we rated it. I will tell you that it was an interesting discussion."

Gerstenmaier said the debate marked "a difficult situation because we have data that shows we have potentially cracks underneath large foam or foam that's put on top of other foam. And we have flight history that doesn't show that we lose a lot of foam. ... So the dilemma is, how can we not rule out that at some point in the future we're not going to have some larger foam loss with this underlying problem? And therein lies the debate.

"We can't figure out the theory that can explain to us why we haven't had larger foam loss," he said. "Obviously, there's something we think that's protecting us in the physics of the situation, but we don't know what that is. What we discussed as an engineering team are what the pros and cons of that are, we looked at statistical models, we looked at transport models, we looked at all of this as a team. ... There wasn't a united engineering position on this.

"We laid out our rationale for the decision to go fly and really, no one objects to the decision to go fly," he said. "Both the safety office and the chief engineer, their point was they recommend being no-go but they don't object to us going to fly. ... The problem is, without understanding this underlying failure phenomenon, any fix we put on has some risk associated with it of losing foam or generating ice. We can control that as much as we can through design, but we can't eliminate that. So in a sense, we almost need to go fly to gain some more data."

Asked again by CBS News to explain how senior managers could cast a no-go vote in the FRR and yet say they agreed with launching Discovery anyway, Griffin made another attempt to explain the flight rationale.

"Some of the senior NASA individuals responsible for particular technical areas expressed that they would rather stand down until we had fixed the ice-frost ramp with something better whereas many others said no, we should go ahead," Griffin said. "So we didn't have unanimity. Therefore, a decision had to be made.

"We annunciated a careful rationale for flying that I believe mitigated the concerns that were expressed by the Office of Safety and Mission Assurance and by the office of the chief engineer. And in fact, they agreed with that. I don't want to say there's no ascent risk. There's plenty of ascent risk on the shuttle. Debris shed from the tank does not pose an ascent risk for the shuttle. OK? It poses a risk for entry.

"Since we have inspection methods, we are beginning to converge on some rudimentary repair methods, since we have the station for a safe haven, since ... we've got an excellent capability for launch on need and we have the Russian partners, we have a number of mitigation strategies should the unlikely occur and we have a debris strike. Subject to those conditions, the chief engineer and office of safety and mission assurance were OK with launch.

"Looking at their specific discipline areas, they would recommend that we stand down. But there are larger considerations. If we stand down, now we back up station assembly flights. One of the areas that surfaced during the CAIB (Columbia Accident Investigation Board) investigation was the issue of schedule pressure on NASA. Now schedule pressure for us is a fact of life, but it has to be balanced. I do not want to make decisions today which are going to result in having all the schedule pressure in creating station assembly in the last year or two. I don't want to get us into a situation where by being more cautious than I think technically necessary today, we wind up having to execute six flights in the last year or something. That's not smart.

"So I'm willing as administrator, looking at the whole picture, I'm willing to take a little bit of programmatic risk now - and notice I did not say crew risk - I'm willing to take some programmatic risk now in order to prevent an excessive buildup of programmatic risk later on. This is, in fact, what you pay me to do. The chief engineer and the Office of Safety and Mission Assurance are not paid to worry about schedule risk four years in the future, they're paid to worry about what is the situation with this particular flight. We had their input. In fact, both of them are long and valued friends of mine and people whom I have nothing but the greatest technical respect for. That goes without saying. But I cannot possibly accept every recommendation which I am given by every member of my staff, especially since they don't all agree.

"I don't know how to say it any more clearly, I'm sorry. I'm really doing the best I can here."

Discovery's countdown to launch on the 115th shuttle mission is scheduled to begin at 5 p.m. EDT on June 28. Liftoff is targeted for 3:48:15 p.m. on July 1.

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      DIAL-UP: part 1 and part 2
      BROADBAND: part 1 and part 2