Eager to get the aging space shuttle fleet flying again to finish building the International Space Station, NASA officials are pressing ahead with the scheduled launch of the shuttle Discovery this weekend despite having failed to fix the shedding of foam debris that doomed Columbia and its crew in 2003 and narrowly missed Discovery on its last mission 11 months ago.
NASA Administrator Michael Griffin frankly acknowledges that he is risking the loss of Discovery–and the rest of the space shuttle program–should another chunk of foam from the shuttle’s external tank break off and strike a vulnerable section of the orbiter during its ascent into space.
But Griffin said he is confident that NASA is not risking the lives of Discovery’s seven-member crew, because the chances of a catastrophic foam strike are low, the astronauts could attempt spacewalk repairs if any damage is detected and, in the worst case, the crew could climb aboard the space station and await rescue by the shuttle Atlantis, which is being readied at the Kennedy Space Center in Florida as an emergency backup.
“I don’t believe we are taking a crew risk,” Griffin said this month after approving Discovery’s launch, scheduled for Saturday afternoon. But, he added, “if we were to lose another vehicle, I will tell you right now that I would be moving to figure out a way to shut the program down. I think at that point, we are done.”
Foam stalls more missions
Three shuttles remain after the losses of Columbia three years ago and Challenger in 1986, and NASA officials want to keep them flying for 16 or 17 more missions over the next four years to complete the heavy lifting necessary to finish the long-delayed space station. Then, in 2010, the shuttles will finally be retired–decades later than their original planned obsolescence date–so NASA can concentrate its budget and scientific resources on building a new generation of spacecraft to take astronauts back to the moon and on to Mars.
But those remaining missions have been slowed by the vexing problems with the insulating foam debris, which engineers have reduced but not eliminated despite two years of work and the expenditure of more than $1 billion. Technicians removed some of the ramps where foam was shedding and reconfigured others, but officials acknowledge that they still expect to see some small pieces break off during Discovery’s launch.
Columbia was destroyed when a suitcase-size piece of foam tore a hole in the leading edge of the orbiter’s wing, a mishap that was detected by NASA engineers a day after the launch while the orbiter was continuing its mission but downplayed by senior NASA managers (this sentence as published has been corrected in this text). When the shuttle re-entered Earth’s atmosphere on its return home, superhot gases penetrated the hole and caused the spacecraft to explode.
After that disaster, NASA installed an elaborate series of cameras on the ground and aboard the shuttle and space station to enable close inspection of foam shedding during launch and any damage to the orbiter’s exterior that might result. Those cameras revealed that during Discovery’s first post-Columbia test flight last July, a 1-pound chunk of foam broke away and nearly struck the spacecraft.
“The bottom line is that the shuttle is probably no safer, nor no worse, than it was prior to all of the repair activities that we started on so long ago,” said Joseph Pelton, director of the Space and Advanced Communications Research Institute at George Washington University and an expert on astronaut safety.
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Size of threat disputed
How great a threat the foam chunks pose is the subject of intense debate inside NASA. Officially, the space agency categorizes the problem as “probable-catastrophic,” meaning that a foam strike serious enough to cause the loss of an orbiter is likely to happen at some point during the remaining life of the shuttle program.
At a June 17 flight-readiness review meeting attended by senior NASA engineers and shuttle managers, the agency’s top safety official and chief engineer advised against launching Discovery until the problem of foam breaking off sections called “ice/frost ramps” could be fully resolved.
But Griffin, acting on the advice of other senior shuttle officials, overruled those concerns and authorized the launch, citing the remote possibility of another serious foam incident and the availability of repair and rescue options should such an accident occur.
“The question is, can we fly a few times with this ice/frost ramp without probably incurring a hazard?” Griffin said. “Based on the data that I have seen, I believe that we can.”
Yet the failsafes NASA is relying on are largely unproven. Although spacewalking astronauts during last year’s Discovery mission successfully fixed a piece of spacer material that was protruding between the orbiter’s thermal-protection tiles, none of the other experimental techniques for repairing the shuttle’s wings or thermal tiles have been certified to work under actual flight conditions.
Even if a patch were successfully applied to a hole, NASA officials would then have to determine if the repair was reliable enough to risk a journey home.
Meanwhile, the rescue-shuttle option is fraught with so many unknowns that shuttle program manager Wayne Hale said last year it was an option the space agency preferred to avoid.
“Pulling off a successful rescue mission in the amount of time we have available is certainly not a guaranteed thing,” Hale told the Orlando Sentinel.
Atlantis shares same risks
The space station has enough oxygen, food and water to sustain the seven Discovery crew members, plus the American astronaut and Russian cosmonaut who are on board the station, for 82 days, NASA officials say. Atlantis, meanwhile, would require at least 35 days to be readied for a rescue flight. But that apparent 47-day margin could shrink depending on the situation aboard the space station and any problems that developed with Atlantis.
Moreover, Atlantis would risk experiencing whatever problem disabled Discovery.
“You would have to hedge your bets that everything goes well that day” with the launch of Atlantis, said Tony Ceccacci, the lead flight director for the Discovery mission. “You always have the concerns as to what caused the damage [to Discovery] and are we willing to launch the rescue vehicle into that same concern.”
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NASA Administrator Michael Griffin
Big decision: He decided to launch shuttle Discovery on Saturday despite the concerns of two senior safety officers. “The administrator … has the obligation to decide. That’s what I do,” Griffin said this month.
Looking ahead: He cited scheduling pressures as a reason to launch–a delicate topic because expert panels found such pressures were a major contributing factor to the 2003 Columbia disaster. “Schedule pressure … has to be balanced,” Griffin had said. “I do not want to make decisions today which are going to result in having all of the schedule pressure … in the last year or two [of the shuttle program].”
Background: Griffin became the 11th NASA administrator in April 2005. Previously he headed the space department at Johns Hopkins University’s Applied Physics Laboratory; earlier, he was chief engineer and associate administrator for exploration at NASA.
Credentials: He has a doctorate in aerospace engineering and four master’s degrees in electrical engineering, civil engineering, applied physics and business administration. He is lead author of the textbook “Space Vehicle Design.”
Sources: Tribune staff reports and news services