The most dangerous launch, ever???
Published on May 11, 2009 at 4:10 pm.
4 Comments.
Filed under space shuttle, space telescopes.
Last night and this morning, I was listening to the news on television. Both times, the news anchors were covering the STS-125 mission to the Space Telescope. Both times, the person covering the story stressed how hazardous this mission is. One said that it was the most dangerous mission that the Space Shuttle has ever undertaken. The other called it NASA’s most hazardous mission. Huh? Do they know something that I don’t know? More likely, I know something that they don’t know. This mission is no more hazardous than any other mission to the Hubble Telescope. Several news organizations have also said that this is NASA’s fourth flight to HST. Yes, it is Servicing Mission 4, but that does not mean that it is the fourth flight. Servicing Mission 3 was broken into two flights: Servicing Mission 3A (STS-103, in December 1999) and Servicing Mission 3B (STS-109, in March 2002). If you include STS-31, the mission that deployed the Hubble Telescope, then this is the sixth Space Shuttle mission for HST support. This mission is no more dangerous than any of the others. In fact, I can argue that it is the safest of them all!
First of all, why is everyone saying that this mission is so dangerous? Well, this goes back to a decision after the loss of the Columbia as it broke apart over Texas at the end of the STS-107 mission in 2003. Until that time, no American manned spacecraft had been lost during reentry. Despite the engineers and crew knowing that this was an extremely dangerous part of the mission, the public and non-engineer administrators in NASA had gotten a little complacent about it. After all, NASA had been so successful that it seemed routine to come through this hazardous part of the mission without any problems at all. Then, Columbia was lost, along with seven astronauts. The problem was a piece of debris shed during liftoff that struck the wing of the vehicle. The damage was serious enough at a critical part of the vehicle that the structure of the wing failed, and the Columbia spun out of control and was torn apart in a fiery reentry.
The loss of the Columbia was a blow to NASA and to the Space Shuttle program. It was the second Space Shuttle lost (the first being the Challenger in 1986). A lot of safety factors were put into place after the Challenger accident. However, by 2003, NASA was under the gun to stay on schedule and to get missions off without delaying them too much ( much the same as in 1986). No one thing doomed either mission. There were a number of factors that led to each accident. I won’t go into them here, but I did write an encyclopedia article a few years ago about the STS-107 mission, and I did quite a lot of reading up on the accident. There was more than one bad decision that was made.
One of the factors leading to the loss of the Columbia was insulating foam coming loose from the shuttle’s external fuel tank during launch. Actually, there is still some debate on whether it was foam or a foam and ice mixture. It doesn’t really matter. Foam loss had been an issue since the early days of the Space Shuttle program. The first fuel tanks were painted white, but to save weight, the remaining ones remained unpainted. The foam, itself, is the orange substance coating the tanks. Previous shuttles had been damaged. The matter only got worse when the manufacturing process for the external tanks was changed to be a bit more environmentally friendly. Little known to many, only a couple missions prior to STS-107, a piece of foam/ice came loose and struck one of the supports holding one of the solid rocket boosters to the external tank. The strut was bent. Had it come loose, then the rocket would have torn away in such a way as to probably result in the loss of the shuttle. It was probably a mistake to keep flying missions until the foam issue had been brought under better control, but it is much easier to point fingers in hind sight than it was to see the danger at that time.
The danger posed by foam/ice strikes had gradually been downplayed. After all, foam strikes were not uncommon, and they had never caused the loss or serious damage to a shuttle (some notable damage had occurred, but nothing that seriously threatened the vehicle). All that changed, though, with the loss of Columbia. There was a temporary halt to all Space Shuttle missions. When, missions resumed, the decision was made to forgo all flights except those to the International Space Station (ISS). If the shuttle were damaged on liftoff, then it could stay at the ISS until rescue arrived. The shuttle does not carry enough fuel to fly all over space. It has enough to do its assigned mission, and little more. So, any mission not to the ISS could not fly to the ISS if there was damage on liftoff. Thus, any mission not to the ISS would be stranded in space if the spacecraft were damaged on liftoff. Further missions to the HST were, therefore, canned. Lobbying by astronomers, the public, politicians, and astronauts finally gave NASA administrators a good reason to reconsider the ban on missions to HST. But, there was still the matter of what to do if a shuttle were damaged on liftoff.
In my previous posting, I wrote that early plans called for near continual launches from NASA’s spaceport at Cape Canaveral (the Kennedy Space Center). NASA has always been good planning for the unexpected. There was talk about perhaps having a Space Shuttle rendezvous with a damaged Space Shuttle in orbit to effect a rescue of the astronauts of the damaged one. I remember reading while I was in college about a rescue capsule that was being developed to transport injured astronauts from one vehicle to another without the use of a spacesuit. I remember buying a book called the Space Shuttle Operator’s Manual that made such capsules seem like common equipment aboard the shuttle. So, under pressure to save the HST, NASA administrators apparently dusted off the old concept of a rescue mission. Sort of the original idea, though, was that there would be so many shuttle missions lifting off all the time that it would be pretty easy to retask a shuttle from its planned mission to a rescue run. But, the idea that there would be shuttles lifting off every week was quite unrealistic to start with and was never realized. Very seldom has there been a situation where there were two shuttles on their launch pads at the same time. So, NASA has to plan for this situation to occur. Thus, until this afternoon, we had Atlantis sitting on Pad 39A and Endeavour sitting on Pad 39B. Now, Atlantis is in orbit.
So, this brings me back to what I started this post. What makes this mission so dangerous? The answer is … nothing different. Any Space Shuttle launch could result in damage to the orbiter. That this mission is so dangerous that it could not be attempted without a rescue shuttle sitting ready to go (what the reporters made it sound like on the news) is a bit melodramatic. This mission is poses no more danger of damage to the orbiter than any other mission. The difference is that after the Columbia loss there is more public awareness of the dangers of spaceflight. The risk had always been there that a shuttle may be damaged on liftoff too badly to safely return to Earth, but that risk had been downplayed since no American spacecraft had ever been lost during reentry. Had the level of risk awareness and risk tolerance been what it was in the past that it is today, there probably would have always been another shuttle sitting ready whenever a shuttle launched. This mission is not more dangerous than others. The hazards of space travel are simply better and more widely understood and recognized. That is all.
Oh, and I said that this might actually be the safest mission. How is that? Well, it is the only Space Shuttle mission to fly with a rescue shuttle in position if needed! So, that would make it the safest mission in the history of the Space Shuttle program.
So, if anyone from the media is reading this, maybe that would be a better story than that this is such a dangerous mission unlike any other, because it isn’t. That’s just my two cents.
-Astroprof
Image credit: NASA/Fletcher Hildreth
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Sili on May 12, 2009 at 1:01 pm: 3
Well, the amount of orbital debris is higher than previously, I think.
This is gonna sound callous, but what is the ‘risk’ of shuttle flights compared to some more ‘common’ occurences? Say ordinary flying, non-combat military flights, test-piloting, that sorta thing?
The reason it sounds callous is that it is callous. These are indeed extraördinary men and women and they do indeed deserve that we take every reasonable precaution to get them back safe. But at what point does the precautions become unreasonable? There are after all strapping themselves atop giant rockets. Death is indeed a likely outcome - shouldn’t they resign themselves to that?
Mistakes have been made in the past. As always with bureaucracy costcutting, carelessness and laziness. But are we not going too far in the other direction now? Noöne dares be the one to lose another crew, so now everyöne tries to cover their derrière to the point that nothing can get done.
Astroprof on May 12, 2009 at 1:32 pm: 4
Sili,
You’ve got a very important point here. Space travel is indeed inherently dangerous. The astronauts generally know this and accept the risks in order to be participants in the era of space exploration. The rest of us need to accept those risks as well. After all, auto racing is also dangerous. There is no call to end auto racing when a race driver is injured or killed in an accident. It is accepted that risk is part of that sport. Everything reasonable is done to make the cars as safe as possible and to provide emergency assistance to the drivers in the event of a crash. As for space travel, every reasonable precaution should be taken, but we have to accept that space travel is risky. We should do everything reasonable to make sure that the astronauts return safely. But, if we wait until there is no danger at all, then we’ll never get anyone into space.
As for the orbital debris problem, I agree that there is a bit more debris than before. However, I think that the media has been blowing that out of proportion, too. There is the danger posed by orbital debris from any other shuttle flight, too, not just this one.