I've always found the relative impact velocity of the foam piece with respect to the shuttle quite surprising. There is some clarification of this in the CAIB report, chapter 3, page 60 (http://www.nasa.gov/columbia/home/CAIB_Vol1.html):
THE ORBITER “RAN INTO” THE FOAM
“How could a lightweight piece of foam travel so fast and hit
the wing at 545 miles per hour?”
Just prior to separating from the External Tank, the foam was
traveling with the Shuttle stack at about 1,568 mph (2,300
feet per second). Visual evidence shows that the foam de-
bris impacted the wing approximately 0.161 seconds after
separating from the External Tank. In that time, the velocity
of the foam debris slowed from 1,568 mph to about 1,022
mph (1,500 feet per second). Therefore, the Orbiter hit the
foam with a relative velocity of about 545 mph (800 feet per
second). In essence, the foam debris slowed down and the
Orbiter did not, so the Orbiter ran into the foam. The foam
slowed down rapidly because such low-density objects have
low ballistic coefficients, which means their speed rapidly
decreases when they lose their means of propulsion.
where p is the density of the fluid the object is moving in, v is the velocity of the object relative
to the fluid, C_d is the coefficient of drag and A the cross-sectional area. C_d is around 1 for most geometries (http://en.wikipedia.org/wiki/Drag_coefficient).
In the CAID report, the dimensions of the foam is estimated to be 19x11.5x11.5 inches, which is roughly 0.5x0.3x0.15 meters. Assuming the foam fell with the smallest surface pointing down (a bad assumption), we can estimate A to be 0.045 m^2.
According to Wolfram Alpha, the density of air at 20km, the altitude at which the foam broke off, is 0.089 kg/m^3. The initial velocity of the foam was about 1568 mph which is around 700 m/s.
Plugging all of this in to the above equation gives:
F ~= 981 kg*m/s^2
The mass of the foam was estimated at 1.6 lbs, or around 0.7 kg, and using F=ma we can calculate the acceleration to be about 1400 m/s^2. The foam traveled for 0.16 seconds before striking the shuttle, and assuming that the above force was constant during that time (thus overestimating the change in velocity), that would result in a delta_v for the foam of 224 m/s, which is about 500 mph.
This is all assuming of course I didn't make some trivial mistake with the math, which I probably did.
It would be great if someone with more knowledge than me could chime in about drag near the speed of sound (or multiples of the speed of sound).
The CAIB set up a dramatic recreation of the incident in which it used a nitrogen gun to fire a piece of foam at ~500mph at a test panel. NASA was not happy with the idea of the experiment feeling it was a waste of time. There were audible gasps from the crowd of engineers when the foam punched a head-sized hole in the panel. Bingo.
Came here to make sure that this article was posted. It's an engaging and well written examination of the followup to the Columbia's loss. Thanks for linking to it!
Not a whole lot. The Shuttle's max acceleration during launch was around 3 gees, and at this phase I believe it was more like 2.5 gees. 0.161 seconds at 3 gees is under 5 meters/second change in speed.
Thanks very much. I had always assumed the Shuttle's max acceleration was a lot higher than that, given how fast the thing seems to get moving in such a short amount of time.
It takes about eight minutes to get to orbit. Which is quick, but not super quick. Reasonable accelerations reach really high speeds when you just keep doing them for minutes at a time. For example, a fast race car might be able to pull off a similar acceleration, but only for a few seconds before it can't go any faster.
Acceleration at liftoff is lower than maximum acceleration during the rest of the launch.
Most of the mass in a rocket is fuel. As the fuel is burned off, the same amount of thrust gets divided over a progressively lower remaining mass.
The Shuttle stack has a mass of 2.03 million kg at launch, and delivers 30.45 MN of thrust. That's 15.0 m/s² of acceleration, or 1.53 g's. (Because it's thrusting vertically, though, it only accelerates upward at 0.53 g's.) This is much lower than the maximum acceleration attained later in flight.
I loved this article. Teared up a few times thinking about how things could have gone differently.
I had an opportunity to tour Kennedy Space Center in December. I think many people have this idea that the NASA of today is a shadow of itself and that it's stagnating. I had an opinion something like that.
To my surprise, NASA is in the middle of some very interesting work. They've completed a new gantry/launch tower for their next generation of rockets which will be close to or bigger than the Saturn V. Several of the launch pads have been completely retrofitted. There's a lot of cool activity going on that we'll start seeing on the big stage in the next couple of years.
It was heart breaking to see one of the shuttles hanging in the museum. They really are beautiful, utterly massive machines. You can only get a sense of loss looking at them, feeling that we're missing something big by having removed them from service.
But looking back, despite their majesty the shuttles took a lot of work to do relatively little. (Little in this context is still a huge amount.) It was time to retire them.
I'm cautiously optimistic about NASA's future. The idea of being more of a support role for commercial manned space may seem beneath them, but it's not. They will continue doing the types of projects that are impossible for companies, including manned missions.
> It was heart breaking to see one of the shuttles hanging in the museum. They really are beautiful, utterly massive machines. You can only get a sense of loss looking at them, feeling that we're missing something big by having removed them from service.
I think this is the main problem with the space shuttle. They look good in a museum. They look good in a postcard. They have a mix of cutting edge, unproven, easy to break technology. They are a dead trap and explode in 1/50 launches.
According to Wikipedia the Soyuz have 4 dead astronauts, in 1700 launches. (No deads since 1971, and they change the model, so the new model perhaps is safer or perhaps they are lucky.) But they are "cheating", because most of the missions are unmanned. When they explode, usually nobody dies. The death rate is also approximately 1/50, But they only put humans when it's necessary.
If you add up all of the US launches then its numbers don't look so bad either. It's not quite apples-to-apples. The big problem with the shuttle was that it was a non-solution to arguably a non-problem, and having created this very expensive non-solution, a mission had to be found for it. And it also turned out to be horribly unsafe (aside from the people lost in the Apollo fire -- which was during a training exercise, all of the US casualties in space vehicles have been from the shuttle).
E.g. one of the highest profile achievements of the shuttle program was repairing Hubble. But without the shuttle program Hubble would simply have been replaced (more cheaply). IIRC it turns out that the US air force had (and presumably still has) several superior telescopes sitting in warehouses in case they need to replace a spy satellite in a hurry.
And of course the single biggest achievement of the shuttle program is the ISS which is an utter boondoggle.
The ISS is definitely expensive and doesn't produce much tangible return. But they are up there doing research 24/7, and have been for more than ten years.
I still like it a lot better than the alternative, which is to have nothing. Wikipedia says we have spent $150 billion on the ISS. That's very expensive but it's cheaper than a war and only slightly more expensive than the TSA. At least the ISS has a net positive impact.
Slight correction: they are up there doing "research" 24/7.
The alternative to the ISS is not nothing; and it's hard to demonstrate that it's a net positive. I'd happily agree that the TSA is a negative, but "better value for money than the TSA" is hardly an awesome rallying cry.
When visiting the Technikmuseum Speyer recently, I had the opportunity to see an actual Buran, the Russian Space Shuttle, on display.
Today, it is easy to forget that the Russians percieved the Space Shuttle as a weapons platform. The tactical advantage of "coming out of space" to deliver a payload made them build their Space Shuttle clone.
Buran never had any civilian purpose. After all, they were quite happy with Soyuz for all research purposes.
The Shuttle may not have been a weapons platform, but it was designed specifically with military missions in mind. It was given it's massive cross-range capability (those massive wings (and mass that goes with them)) so that it could return from polar orbit missions. There was an idea of going into polar orbits and literally snatching Russian spy satellites out of the sky and flying them back to the ground.
No polar orbit missions were ever performed, however there were several classified DoD missions to orbits with lower inclinations.
And, as I recall, part of the agreements to fund the Space Shuttle to begin with came from the military and spy agencies: a better capability to launch and service spy satellites.
When the Space Shuttle program began, they planned for hundreds of flights, around 50 per year. The shuttles were only designed to last 100 missions before retirement. We were supposed to get a new shuttle rotating into service every 4 or so years.
I toured Kennedy back in 2011 while STS-134 was sitting on the pad. I didn't quite have the impression that NASA of today was a shadow its former self, but I sure walked away from the tour thinking it was.
Learning that the giant VAB sitting there was constructed for one purpose: Building a Saturn V. Learning that the crawler that moved the craft around were built for one purpose: Moving a Saturn V. Then moving on to the most interesting part of the tour, not the shuttle sitting out there on the pad, but a giant warehouse with a Saturn V on its side inside.
Everything seemed to be in a slight state of decay -- not entirely neglected, but definitely from another age. The age of the Saturn V. The biggest impression I got from the whole experience was both awe inspiring, and sad: Apollo was NASA's zenith, and the future doesn't look quite as bright as those days in the 60's.
I'm hopeful that I'm wrong, but every part of the experience reinforced in me the belief that NASA's glory days had come and gone.
Yes, it's a bit sad and Apollo was an incredible set of engineering but let's keep something in mind: the massive budgets of the "space race" were fueled by Cold War tensions. A not-so-subtle implication of the space program was you'd better spend ridiculous levels of resources on rocket research or risk being dominated from above and by the way look how precisely we can land things back on earth.
I'm not going to complain about the result, but neither do I miss all aspects of it.
When the Space Shuttle program was decommissioned in 2011, the U.S. lost human spaceflight capability. We are at a point in U.S. history that is similar to the human spaceflight gap that existed between the Apollo program and the Space Shuttle program.
There is an American flag that flew on-board STS-1. It was left on display in the ISS by the crew of STS-135. It is awaiting return to the U.S. by the next American crew that is launched from the U.S.
I do my best to embrace the concept of being a citizen of the world rather than of a specific country, but I can't help feeling a little patriotic. Like many of you, I grew up watching the Space Shuttle launches; all of those memories of both the successful launches and the tragic losses. That zeitgeist you grew up with, seeing those launches: it indelibly marked young people like us, with the knowledge and firm belief that, anything is possible through science and technology, perhaps even more so because it was during that time that we were teaching ourselves to program on our Commodore 64, Atari 800, etc.
Perhaps this feeling is heightened for me now, because in the U.S., I think there has been an under-current feeling for some time now, that could be paraphrased as, "Where are we heading, as a nation?"
I still believe in those child-hood dreams, and my eyes get a little misty, thinking of when we will launch into space and bring that flag home.
SpaceX has done low earth orbit, geosynchronous transfer orbit, and is working on reusable self-landing first stages and human spaceflight. Out of them and NASA, I expect SpaceX to get there first.
When the Space Shuttle program was decommissioned in 2011, the U.S. lost human spaceflight capability.
The real problem is that there are so many people who either don't care or think space exploration is a bad thing.
If you look at some polls you get half of all people polled not knowing that Armstrong landed on the moon and a fairly clear majority opposing the idea of spending public money on going to Mars.
So now there is the situation that NASA lost the ability to get people into space and only the nerds complained. It is going to be very difficult politically to get that capability back.
I think the question is not whether it's a good idea to return humans to space (of course it is), but what it will accomplish and at what cost.
You can make observations such as, "You have to feed the soul, too!" (from The West Wing after Josh mocks the cost of Mars Direct). However, there are serious problems on Earth in the U.S. that cannot be solved by developing manned spaceflight tech, and those concerns are going to override thoughts about manned spaceflight for most people most of the time. What drove the space program (first unmanned, then manned, then to the Moon) was national pride and the desire to out-compete the Soviets. I don't see any available current of feeling that could generate similar support today.
Ignore the Shuttle for a moment and imagine we'd kept human-carrying spacecraft perched on top of rockets, like we did before; in other words: safer, cheaper, manned spaceflight in the modern era. What has manned spaceflight achieved in the last 30 years? We've serviced some satellites, certainly, but at what cost compared to simply deorbiting them and launching new ones? Experiments in space have advanced medical and materials science technology somewhat, but consider how far we could have advanced if all the money thrown at the Shuttle and ISS programs had been allocated to automated/remote-controlled experiments and, where possible, simulations. Whatever the difference is, those are missions where you could make a case for a manned mission to conduct experiments, but I doubt there would be very many.
Next, let's imagine a hypothetical Zubrin-inspired mission to Mars. It would inspire everyone, but for how long? People don't stay inspired forever, and suppose it becomes apparent that we'll never go back to Mars again because the cost/benefit is too high, or heaven forbid if the mission fails because the astronauts die unexpectedly. Things on Earth become worse because the hope of productive Mars missions will have dimmed.
Americans have become much more risk-averse. I think that without a strong and sustained reason for sending humans back to space on a long-term or regular basis, we shouldn't bother. Space is not a very nice place for humans, even with all our technology. There's plenty of inspiration available by accomplishing things in space without risking astronauts' lives to do so.
> "However, there are serious problems on Earth in the U.S. that cannot be solved by developing manned spaceflight tech, and those concerns are going to override thoughts about manned spaceflight for most people most of the time."
If you spent the entire US Federal budget fighting worldwide poverty, you'd end with less than $500 to spend on every person every year.
We should not spread wealth and advantage thin trying to fill in every low point. Even the Bill and Malinda Gates Foundation doesn't wait until everyone is vaccinated before putting money to other "higher level" activities such as research. Moreso, I am glad that there are charities which primarily concern themselves with providing large amounts of money to speculative research instead of spreading that money thin on lower level concrete but ultimately fleeting activities. All that cancer research money could be spend paying the hospital bills of people who are currently undergoing treatment, but I much prefer it being spent on research.
Charities that focused on paying hospital bills would be great, but not at the expense of charities which focus on research. There is room for both, but we should not cut back on funding for high level research and advancement because there are still low-level concerns to be addressed.
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Alternatively, more succinctly: If we had spent all that Apollo money on malaria instead, would we still be fighting malaria today? I think that is near certain.
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Alternatively, more metaphorically: If you are tasked with tracing the outline of a Koch snowflake and tracing the outline of a square, would you hold off on tracing the square until the Koch snowflake was complete?
What has manned spaceflight achieved in the last 30 years?
Just in terms of encouraging political cooperation between Russia and the USA with the ISS, it has been priceless.
Other than that, we are learning about human spaceflight, if you think that is not worth the bother in and of itself, then ultimately you are choosing from a dark selection of futures.
edit -
There's plenty of inspiration available by accomplishing things in space without risking astronauts' lives to do so.
If you don't risk astronauts' lives by sending them into space, then you don't actually have any astronauts at all.
Interesting to remember the Columbia tragedy while recalling Richard Feynman's report summarizing the culture problems at NASA he found following the Challenger disaster. It's clear that NASA ultimately learned very little (or forgot it after 15 years).
No matter the state of the shuttle program, it's also a shame that NASA didn't maintain a non-reusable rocket system that could have allowed for expensive but relatively low-risk emergency flights for this sort of thing. If the shuttle's all you've got then it's going to be difficult to address unexpected problems with another shuttle just like it.
No, it's a coincidence. The foam was a disaster waiting to happen from day 1. The second mission after the Challenger disaster was nearly destroyed by foam. The two astronauts who inspected it in orbit were certain they were going to die. (In this case, rescue was impossible.) Miraculously, the worst damage was over an unusually sturdy part of the shuttle.
Not really, it's just random chance mostly, at least during the Shuttle program. The Apollo program was too short to draw firm conclusions from.
People often believe that NASA had bad luck when they lost Challenger and Columbia, the truth is the opposite, they came extremely close to losing a lot more crews. On the very first flight, STS-1, there was a serious problem with the body flap on the orbiter caused by an overpressure wave from the SRBs, John Young, the commander of the flight, said that if he had known of the problem during takeoff he would have bailed out during launch. Later flights had other, equally serious problems. STS-8 came very close to suffering the same fate as Challenger. STS-9 could have easily been lost if the computer crashes that occurred in flight happened during re-entry or to the fire and explosion of 2 out of 3 of its auxiliary power units, which occurred just after touchdown, fortunately. STS-27 suffered sever TPS damage and could easily have been lost just as Columbia was.
For many of these issues NASA worked on fixing them but never acknowledged the full extent of the risk and mostly just pretended that everything was OK up until something bad happened. If the fires on STS-9 never occurred an APU disaster could have resulted in loss of a crew during a flight. Even though TPS damage from foam/ice strikes happened on many flights NASA was never able to tackle the problem and merely got away with being lucky, right up until the loss of Columbia on STS-107.
This does seem to be a reasonable amount of time to scrub institutional memory within the band of middle management ultimately responsible for the decisions and culture of the institution. Seems like a topic ripe for management and I/O psych research... I assume something like it has already been well tread.
I've seen similar arguments for cycles of pacifism and militarism in populations as a whole over a longer period of time -- a couple of generations typically. Interesting observation.
Of course, hindsight is always 20/20. If we sent a successful rescue mission, we would instead be reading an article entitled. "Columbia Rescue: NASA's finest hour or giant waste of taxpayer's dollars?" with a bunch of supporting evidence on why the rescue was unnecessary.
Isn't the shuttle capable of being run autonomously? I know it can be landed without human intervention, but isn't the crew more or less cargo for the whole trip as well (except for tasks such as running experiments)?
Not that there wouldn't be volunteers and a reputational benefit to sending a solo or two-man crew up.
The American Space Shuttle was intentionally designed to require a human to flip the landing gear switch. The autopilot was capable of doing everything up until that point -- the S curves, the approach, the flare.
The astronaut corps wanted to say that the Shuttle required a human at the controls.
Since STS-121, the second return-to-flight mission, Shuttles have carried a data cable that would allow the landing gear to be lowered by the flight computer. However, this cable is not installed by default, and would be plugged in only if the crew had to leave.
In 2003, this capability would not have been available to Columbia. If the crew left, then it would have been the end of Columbia.
Doubtful. Appolo 13 showed that the public really likes bringing the astronauts alive. And even the most fervent republicans will have hard time presenting saving the lives as waste.
God, how I despise it when people have to bring their petty partisan politics into every discussion.
No sane person in the United States of whatever political party or creed would have said a rescue mission that had a reasonable chance of success was not worth the money and risk. [EDIT] Assuming it was understood that the spacecraft was in mortal danger.
According to the article, it would have been highly unlikely that the Atlantis could have rescued the Columbia astronauts. Possible, but just barely. Should they have tried? Maybe. Should they have planned for the contingency? Of course--if they had an extra couple billion dollars budget for such a project. 20-20 hindsight.
You can't go to space on the cheap. The old Nasa slogan to promote the Shuttle--faster, better, cheaper--is proven incorrect by historical events. You can have 2 of those, not all 3.
I meant pundits and politicians not ordinary citizens. I chose republicans because waste is usually one of their favorite talking points. So chances are if a voice arises it will be from their side.
My opinion is that it was impossible to pull that thing off. And it showed a cultural problem in NASA. But that is another story.
"I meant pundits and politicians not ordinary citizens. I chose republicans because waste is usually one of their favorite talking points."
No Republican I've met would think doing a rescue mission was wrong or a waste. Using your logic, I could say it would be the Democrats who wouldn't attempt the rescue and point at Benghazi as the modern example.
Partisan politics are a remarkably poor way to tell a reaction to this type of situation. It really goes to the life experience and culture someone was brought up in.
If they had known and it leaked, and NASA had not moved heaven and earth to try to save the astronauts, then heads would roll. The base culture of the US would allow no other course.
>No sane person in the United States of whatever political party or creed would have said a rescue mission that had a reasonable chance of success was not worth the money and risk.
I think most of us have the sentimental and emotional content that we would want the rescue mission to go forward. However, if you were to ignore the feel-good effects, it is very difficult to argue that the mission would maximize human well-being. I only think it is an obvious decision with a failure of perspective. Let me try to characterize some of the considerations in the most approximate and non-rigorous manner.
Ignoring the risk to the rescuers, let's say the cost of the mission is something like $80M per astronaut life saved. If there is 80% chance of success that is equivalent to $100M/life or if there's a 10% chance of success that is $800M/life.
With big numbers, it starts to become a society-level decision about how individual lives are valued. What are the resources we're willing to devote to the rescue of a trapped coal-miner, the cancer treatment of a child with poor parents, a medical evacuation from Antarctica, or the rescue of someone who has been captured by pirates?
One could argue that these astronauts merit greater rescue efforts, since they are spearheading humanity's exploration into space, but you could also argue that they are sufficiently sophisticated to understand the risks they were taking on.
Let's say an aircraft carrier takes two days to meet up with a cruise ship in the middle of the ocean to airlift a girl with an appendicitis to its shipboard hospital. Does the $20M/day operating cost of a carrier count as resources spent on that one child? Probably not, because thousands of crew members are going about their regular training regardless of where they are, and carrier is doing its job of being some predetermined general vicinity. While the justification for the expense of those other goals can be debated, they don't happen to be an opportunity cost of rescuing that girl.
On the other hand, the shuttle crew rescue mission would likely have been entirely in pursuit of one singular goal. The depreciation and consumption of resources could not be considered to serve other purposes. The salaries paid might be thought of as a transfer rather than a destruction of wealth, yet they too represent the efforts of a large work force of highly competent people not doing another tasks for that same pay.
The other benefits of such a mission really are difficult to project. For example, maybe the value of additional capabilities that would have been developed in pursuit of rescuing the astronauts would have been worth it. Perhaps the feel-good effects alone would have been worth as much as anything else that we spend money on that inspires us.
While it is the task of good leaders to divine when unreasonable expenses should be taken when the incalculable benefits are worth it, terrible leaders can be characterized as people who fail to have perspective and don't appreciate costs, and who make rash decisions without considering the implications.
Utilitarian arguments aside, one reason folks are willing to go out there on a limb is, they feel they have backup. The Marines risk life and limb to 'leave no man behind', and it works - Marines are bat-shit crazy-dedicated.
So the human equation counts too, not just the dollars.
It is an implicit agreement that some quantity of available assets will be subjected to a certain level of risk in order to insure that one man is not left behind. The implicit agreement is not made because it is sustainable in an environment when a large number of marines require a sacrifice of multiples of their number to be rescued, but because of the number of marines who are at risk of being left behind and the quantity of assets that are available to insure that does not happen.
When considering what risk will be undertaken, you have to appreciate that limits to what assets are even defined as available are imposed by what has been certified as battle ready, which is essentially a risk assessment about a unit's likelihood of survival in an engagement with the types of enemies it is designed for. Or, to consider extremes, we don't field child soldiers, and wouldn't even if it were the only way to make the difference between rescuing a marine behind enemy lines or not.
Perhaps tens, or even hundreds of millions, of dollars per astronaut life does not yet venture into the exotic territory where commonplace statements about "sparing no cost" are meaningless, but it is unrealistic to assert that no cost is so great that you would ever choose to compromise your norms instead.
You're ignoring that the military's job is to the defeat the enemy. If a marine is down, then the operation to rescue him/her by necessity involves defeating or inflicting a severe blow to the enemy.
The same is arguably true of a shuttle rescue mission for that matter: having never been done, the thinking and technological requirements of such a thing, and the grand experiment of seeing if it all works, would be worth the effort.
As noted, since the Colombia disaster NASA took to prepping "launch on necessity" shuttle missions.
I agree that it would have been a gargantuan, billion dollar effort to rescue Columbia, with a high risk of failure.
But had they succeeded, or even had they not for that matter, the lessons learned would have been substantial. So I would propose that the effort would not have been money down the drain. It would have captured the public's imagination, escalated the space agency and its astronauts to a heroic status not seen since the 1960s, and taught the nation a valuable and graphic lesson on the costs of skimping on safety, in this case failing to have a backup rocket ready to take off, or an escape module built into the Shuttle, for example.
Had we kept the Saturn rockets alive, as an alternative heavy cargo and human transport system, with a launch-ready rocket on the pad while people were in orbit, then Lee Hutchinson's notion would not have been so far fetched at all.
But that would have cost tens of billions of dollars that the nation chose instead to invest into other projects--military buildups in the 1980s, wars of invasion in the 1990s and 2000s, and so forth. Only the most powerful of politicians could have persuaded the country to spend that kind of money as a contingency. It's just too tempting to redirect it into local (vote buying) projects.
OP Is not saying that the media would claim that saving their lives was a waste of money, he is saying that the media would claim that their life were never in danger in the first place.
The unmanned Columbia orbiter would still burn up a few [weeks/months?] later. Of course even an intact unmanned NASA Space Shuttle would burn up... but since we are hypothesising irrational reactions the emotional impact of seeing the unmanned orbiter burn up on TV would have likely stemmed much of the criticism. All NASA would have to do is point to the pictures of a burning up unmanned Columbia and say, "With or without people on it, that was going to happen."
Particularly after Challenger, I think it would be pretty easy to dismiss any talking heads that criticised the rescue mission as total asshats.
It's hard to imagine an election campaign attack ad better than "Senator Dickensnort used his expense account for lunch 200 times last session... and then he voted against emergency funding for rescuing our stranded Columbia astronauts".
It's really difficult to imagine the proposed approach panning out as intended - the infrastructure for STS wasn't set up for really quick turn arounds. STS's conceptual design was pitched that way (shuttles going up several times a week), but that didn't pan out in design. And the Challenger accident can be blamed in part on a management culture that took too long to accept their engineers telling them that.
As terrible as the Columbia accident was, I think this approach (with so many checks skipped to get Atlantis up as quick as possible) would have ended in the loss of both crews & orbiters. And I think if the Columbia crew knew the full extent of the situation, and also knew of this sort of rescue in the works, they probably would have pressed mission control to just let them try the re-entry themselves.
As terrible as the Columbia accident was, I think this approach (with so many checks skipped to get Atlantis up as quick as possible) would have ended in the loss of both crews & orbiters.
IANARS (Rocket Scientist) but I can't help but think the same thing. The ability to get Atlantis safely into orbit in 11 days beggars belief, as much as I wish it could have been done.
A catastrophic failure of a rescue mission would have killed the Shuttle program then and there. Aside from the loss of now eleven astronauts and two orbiters, the following post-Columbia activities either could not have taken place or would have been limited to what the Russians could do:
21 ISS resupply/delivery missions, 5 ISS crew transfers, a Hubble telescope servicing mission and major delivery and assembly of ISS components (see http://en.wikipedia.org/wiki/ISS_assembly_sequence#Assembly_... to get a feel for how incomplete the station was in 2003)
Additionally, there would have been an impact on SpaceX as the shuttle had delivered their DragonEye sensor test package as well as communications gear to the station.
> As terrible as the Columbia accident was, I think this approach (with so many checks skipped to get Atlantis up as quick as possible) would have ended in the loss of both crews & orbiters.
Agreed. The article touches on the fact that the Columbia disaster has its roots in decisions that were made far in advance of its final launch. Not that this excuses what happened, but I almost wonder if the reason the photographs of the damage were never taken ("miscommunication") was that the people involved knew there was no possibility of rescue, so better to not know and hope for the best.
The Wikipedia article on the disaster[1] strongly suggests that this kind of fatalism had permeated the culture:
Throughout the risk assessment process, senior NASA managers were influenced by their belief that nothing could be done even if damage were detected. This affected their stance on investigation urgency, thoroughness and possible contingency actions. They decided to conduct a parametric "what-if" scenario study more suited to determine risk probabilities of future events, instead of inspecting and assessing the actual damage. The investigation report in particular singled out NASA manager Linda Ham for exhibiting this attitude. In 2013, Hale recalled that Director of Mission Operations John Harpold told him before Columbia's destruction:
"You know, there is nothing we can do about damage to the TPS [Thermal Protection System]. If it has been damaged it's probably better not to know. I think the crew would rather not know. Don't you think it would be better for them to have a happy successful flight and die unexpectedly during entry than to stay on orbit, knowing that there was nothing to be done, until the air ran out?"
Hale added, "I was hard pressed to disagree [at the time]. That mindset was widespread. Astronauts agreed. So don't blame an individual; look for the organizational factors that lead to that kind of a mindset. Don't let them in your organization."
When I was at JSC, a young engineer once referred to Challenger as an accident over lunch. An older engineer looked at him, and said very slowly "Never, ever, call it an accident. Marshall (Space Flight Center) murdered them."
As for Columbia, even if you could turn around, that approach just doesn't make sense to me either. Station keeping for that long, without the RMS? It's crazy. I would have thought they'd just take up 5 extra suits, make one approach, get them over, take CM1 & CM2, and come back later for 3 (I think 3 could get in the airlock in a pinch) and then a third pass for the last 2. Obviously missing something there if that wasn't possible.
Wow, I devoured every word of that article with baited breath. One of the most amazing stories of fiction intertwined with actual events I've ever read.
I wonder how much years will have to pass before it would be acceptable to make this fictional rescue mission into a movie..?
The obvious issue would be everyone walking out of the theater saying "Jeezz, NASA should have obviously done that, idiots. They killed those astronauts because they didn't do that."
The movie Marooned (1969) depicted a Soviet spacecraft rendezvousing with a stricken American spacecraft to deliver oxygen via an EVA. However, it was unable to dock.
This movie was circulating right around the time of the Apollo 13 mission. The movie was shown to Philip Handler, president of the National Academy of Sciences, who approached the Soviets about a common docking system. The result was the Apollo-Soyuz Test Project and the APAS androgynous docking system.
Yeah, but that wouldn't be the movie. Obviously it could focus on them and have many, many narrow misses, but we all know it would still have the Hollywood ending.
The article for me pointed out just how unlikely the entire movie is. I already knew there were a lot of impossibilities in Gravity (changing orbital planes etc) - but reading just how much work it takes to keep two orbiters aligned, and how much work it is to get into and out of a spacesuit. In the movie she gets out of one space suit and then into another, and then out of it again. That right there is impossible from the reading.
Reminds me of what Neil Armstrong said, when asked what he would do if an engine on Eagle broke and there was no chance they could return from the Moon: "I would try to fix it."
One thing not covered in this article (and maybe the CAIB report? I don't know) is whether the Russians could have done something useful in the rescue. Could enough fuel and scrubber tanks have been boosted to Columbia on a Soyuz or Progress to get it up to the ISS?
> One thing not covered in this article (and maybe the CAIB report? I don't know) is whether the Russians could have done something useful in the rescue. Could enough fuel and scrubber tanks have been boosted to Columbia on a Soyuz or Progress to get it up to the ISS?
No.
On STS-107, Columbia was launched into a 39° orbit. The ISS is at an inclination of 51°. It is very expensive to make an in-orbit change-of-plane.
A quick back-of-the-envelope calculation shows that you would need 50,000 kg of fuel to change the orbit of an empty Shuttle from 39° to 51°. The Progress M has a cargo capacity of 2600 kg -- and the Russians launch one every two months. 20 Progresses all at once wouldn't have been very practical.
If you were going to attempt a rendezvous with Columbia from Baikonur, it would be better to send Soyuzes and bring them down two-at-a-time. The Russians do have the Soyuz on an assembly line, but I don't think they have four of them just sitting around.
This is a bit confusing. Since Columbia the contingency plan for all of the shuttles (except one, which was to the Hubble) was apparently to have them go to the ISS and wait there for rescue from the standby shuttle (or later the next mission once the ISS was fully complete). Was Columbia at an unusual inclination for a shuttle mission?
[edit] Answered my own question, this does seem to be the case. At least for the missions after STS-107.
I wonder if a smaller rocket could have been repurposed to simply send extra supplies to the shuttle (or a repair kit) while they waited for rescue? Maybe a soyez?
Even if it couldn't dock with the shuttle, I wonder if it could match orbit and then do a space walk to retrieve the supplies?
Rockets launched from the Soyuz launch site in Kazakhstan cannot reach orbits with an inclination of 39 degrees so there's no way that they could have reached the orbiter from there.
An Ariane launch from French Guiana could have worked and there was a rocket there that launched a satellite shortly afterwards but that would have required fabricating a supply vehicle with automatic guidance and navigation capable of docking to the orbiter by itself. (Ignoring for the moment that the orbiter didn't even have an external airlock with docking collar installed.)
Proton rocket with DM booster and Zond - a version of Soyuz spacecraft, without the orbital module - was launched multiple times in 1960s. DM adds about 3 km/s deltaV. Baikonur latitude is 46N, to get to 39N one needs to change orbital plane for 7 degrees, sin(7)*8 km/s is about 1 km/s. So there could be some options there.
If you launch from Baikonur directly into a 46° orbit, you will drop spent rocket stages on China. That is why the Russians launch into a 51° orbit, even though their launch site is at 46°.
With a Proton, you have enough delta-v to launch into 51° and then make a change of plane to 39°. But the Russians don't just have three Protons and three Soyuzes sitting around, ready to launch. They have to schedule these things.
The Soyuz is normally not launched on a Proton these days -- not since the 1970s. They'd have to jury-rig a bunch of things. It would not necessarily have been safer than a NASA Shuttle rescue.
Very good article, clears up a lot of questions, doubts, and misconceptions.
It seems to me that the problems with the Shuttle program always came down to money. The Nixon Administration denied Nasa the necessary budget to build the larger reusable vehicle they originally envisioned, while simultaneously scrapping the Saturn manned program.
As a space nut since basically I was 5 or 6 years old, when America was in its heyday of Gemini and Apollo programs (I was 10 when Apollo 11 astronauts kicked up lunar dust), space exploration was a given to me and all of my friends.
It was assumed that we would just keep on building and growing our space program until we got to something that resembled Clarke/Kubrick's 2001: A Space Odyssey. Perhaps we wouldn't make it by 2001, but some time not too far beyond then. Maybe 2011. Maybe 2015.
It therefore makes me sad that we've been in this hiatus since about 1974, really 40 years of treading water rather than building much on the accomplishments of the past. Why not a permanent station on the moon? Why not a nuclear propulsion system that could get to Mars in 6 weeks? What have we done instead with our money, that is so much more worthwhile? Why was Nasa denied the $4 billion it needed to continue the Constellation program, while literally hundreds of billions were allocated for bank bailouts, automotive bailouts, etc.? Where are our priorities?
I know these are controversial questions and there are probably some good answers out there, but I go back to the lost dreams, the sacrifices made by the Columbia and Challenger astronauts and others, and I wonder if we haven't traded big dreams for little ones and lost sight along the way of what we're all about.
Money, and in the end, politics. The Shuttle, as implemented, was not really what NASA wanted, but they needed to make design compromises to support certain use cases the Air Force told they need, including launching spy satellites to polar orbits and potentially capturing enemy satellites and bringing them down in one piece. The compromises were made but the Air Force had changed their mind in the meantime and those use cases were never actualized.
Even more about money. My understanding was that NASA came up with a big, awesome plan for a reusable spacecraft kinda resembling the shuttle, and only doing stuff that NASA and their science/exploration missions needed, but they couldn't get anywhere near enough money to build it. So they went to the military to try and get some more money, and they said that they'd kick in some towards it if it could do these other missions they wanted too. They took it and ended up building something that didn't do anybody's mission really well, but it was the only way at the time to get enough money to get something off the ground.
Reading that it looks like the EVA would be a big problem due to getting into the suits.
Would someone who is smarter than me comment on the feasibility (In extremis) of just jumping across the 6 meter gap unsuited 1 by 1 with the suited rescuers helping? I have read that a human can survive about 30 seconds of vacuum without permanent damage. What if they huffed pure oxygen for a while before making the attempt so their blood was super-oxygenated before breathing out and making the leap?
Would the depressurization / repressurization take too long? Would it take too long for the space-suited rescuers to man-handle them into the airlock? (Would they even be able to align airlocks for a straight jump?)
It makes me wonder what would have happened if NASA has a set of minimal protection "short-duration" suits with almost nothing more than pressurization and a small oxygen supply for quick excursions (Like, for example, transferring quickly between two craft as if your live depended on it :p )
Interestingly, it looks like it might not totally be out of the question.
severe symptoms such as loss of oxygen in tissue (anoxia) and multiplicative increase of body volume occur within 10 seconds, followed by circulatory failure and flaccid paralysis in about 30 seconds. The lungs also collapse (atelectasis) in this process, but will continue to release water vapour leading to cooling and ice formation in the respiratory tract. A rough estimate is that a human will have about 90 seconds to be recompressed, after which death may be unavoidable. The low pressure outside the body causing rapid de-oxygenation of the blood (hypoxia) is the primary reason for unconsciousness within 14 seconds. In 1965 Jim LeBlanc lost consciousness after approx 15 seconds of being depressurised.[1]
I wonder if they could have developed some kind of non-space-suit "bag" that would have been enough for a short excursion like this, and easier to get and out of? I suspect getting through the airlocks at each end would have been the big problem.
If you're going to rush a space shuttle into orbit and do a hundred things that have never been done before on a space mission, things like not wearing a space suit during EVA are fairly stupid risks to take.
If you read the original article one of the comments at the end was from an STS engineer expressing his opinion that it would be impossible (not enough propellent, never mind pilot fatigue) for the rescue shuttle to maintain station keeping for the required amount of time to do proper full suited EVAs.
Hence my "In extremis" bit at the beginning before thinking about the feasibility of non-suited. I wasn't asking if it was a good idea (It obviously isn't if it can be avoided)
Going unsuited seems unnecessary - why not grab some reinforced mylar balloons, put the astronauts in them and pressurize, then have the EVA crew shepard them across (possibly on a tether or using the manoeuver packs).
Or if the weight can be managed, a more robust option seems like it would be to be weld a coffin-like container that could fit through an airlock, and put life-support on the inside, then wrap it in insulation.
Either way, we're not talking about a long term thing here - just something which will keep a person alive long enough to be moved between vehicles.
Does make me wonder if you couldn't build some type of inflatable slinky-duct though.
More or less impossible than jumping from one space shuttle to another, in space, in shirtsleeves while suffering from carbon dioxide poisoning and surviving?
I'm just saying that I suspect the people at NASA who wrote this document likely designed the least impossible hypothetical mission after considering a number of approaches, and didn't necessarily write down every approach they considered.
For those interested in a technically detailed fictional account of a rescue mission to Mars, read The Martian by Andy Weir. It raises some of the same feelings as this article.
I'm actually reading it right now, and it's kind of eerie reading the things discussed in the article at the same time as the main character in the book is considering them.
For those interested in a pretty ok movie, Marooned (1969) is about the rescue of astronauts unable to de-orbit after spending months in a space station.
Read Marty Caidin's book instead. It's hard to put down, and contains a nice section concerning Jim Pruett's finishing school that makes you want to become a pilot yourself.
Russia launched about a dozen Proton rockets a year at the time of Columbia disaster, two Soyuz spacecrafts and two-three Progress spacecrafts.
Proton used to launch several Soyuz without Orbital Section, called Zond, in 1960s, with booster DM to fly around the Moon. DM adds about 3 km/s of deltaV. Orbital plane change for 7 degrees - between Baikonur's 46 and Columbia's 39 - takes sin(7)*8 km/s = 1 km/s. So technically it could be considered to launch (several) Progress ship(s) with necessary cargos to Columbia while three unmanned Soyuzes would be prepared and sent to the rescue. Soyuz approaches Columbia, gets caught by manipulator, astronauts use spacesuits from Soyuz - which have to be extracted from Soyuz first.
ISS, meanwhile, had to be kept without ships, which means landing the crew, hopefully temporarily.
All that could be considered. But I don't think anybody high in chain of command considered all of that necessary.
I don't think Columbia had a docking collar, did they even have spacesuits on board? If not, they wouldn't have been able to get to the Soyuz to extract anything. You'd have to send up at least one person one the Soyuz to pass the spacesuits into the shuttle airlock.
Also, I'm not sure Columbia had a manipulator arm installed at the time. It's heavy and they don't fly with it when they're not going to use it.
Yes, there are problems. Soyuz could fly pretty close to Columbia, but to get to the bay could be tricky. It was not going to be a regular docking - but something for a saving mission.
If Soyuz could be taken to the Columbia bay, an astronaut in the Columbia spacesuit could approach Soyuz and open the hatch. Spacesuits could be extracted from Soyuz without entering the spacecraft. Talk about ingenious ideas with rope, attached to the front hatch, etc. The Soyuz spacesuit then is delivered to inside Columbia, where somebody could wear it to get to Soyuz.
If you are interested in the Columbia events, check out Wayne Hale's blog[1]. He was a flight director/space shuttle program manager and offers a very detailed recollection of the events from inside mission control.
What surprises me is that this contingency was not already in place prior to the Columbia accident. Was it budget constraints or did they really think it was that unlikely that a shuttle would be rendered unable to return from orbit and need the crew rescuing?
I think more likely, at some point, you just have to accept the risk.
How far do you take it? 4 launch vehicles all on standby ready to rescue the one before it? Is 3 enough? Maybe 2? Up until then, they had obviously calculated and accepted the risk of having no standby.
So obviously before the incident they were accepting the risk of no standby, where-as they revised that and decided that for a particular mission where using the ISS as a life-boat was not an option, they needed a standby to accept the risk.
Seems like they could have rushed the development of RCO to allow a shot at bringing the empty Columbia back, too. In parallel with all the other preparation efforts, fast-tracking something like that where an already-100%-written-off craft might get saved seems worthwhile.
In an emergency like that, you just put all your engineers and technicians to work in whatever is critical to save the crew. If you have some spare personal, you put them in whatever is very important. Don't worry, you would not have enough people to cover the important task, you must hope that they doesn't mater.
Would they have enough fuel to change orbit to dock to ISS?
If not, would there be enough fuel in Soyuz to undoc, change orbit to Shuttle's and then either re-dock or re-entry?
In terms of safety, it appears that shuttle program became somewhat barbaric by reasonable standards of 21st century. If primary vehicle lost re-entry capability, there should be back up plan for re-suppling it until back up vehicle is ready to take people back. I.e. if failure of Soyuz detected before departing from ISS, they can always sit it out and wait for next one while being resullplied by automatic Progresses.
From page 2: An oft-asked question is whether or not Columbia could have docked with the ISS, which would have had consumables to spare. There are numerous reasons why this would not have been possible, but the overriding one comes down to simple physics: Columbia would have had to execute what is known in orbital mechanics terminology as a "plane change" maneuver—applying thrust perpendicular to its orbital track in order to shift to match the ISS' inclination. Plane change maneuvers require tremendous amounts of energy—in some cases, even more energy than was required to launch the spacecraft in the first place. Appendix D.13 dismisses the possibility of an ISS rendezvous with just two sentences:
"Columbia's 39 degree orbital inclination could not have been altered to the ISS 51.6 degree inclination without approximately 12,600 ft/sec of translational capability. Columbia had 448 ft/sec of propellant available."
For the record, it wasn't possible in Gravity, either.
Well, physics education definitely spoils Gravity somewhat. They tried to do bunch of stuff in realistic manner and crossed into "uncanny valley" of movie realism. During the movie I was "why medical doctor is servicing Hubble?", "no, you are not going to see it coming", "no, don't remove helmet when there is fire in the cabin!"
And, more importantly, "all three of them on the same orbit sequentially if they can go from one to another?". Basically movie implies that. Of course the question is how they got Hubble on the same orbit, since they where servicing it, by theoretically it could have been repositioned during previous missions.
Kerbal Space Program is a fantastic educational platform for actually trying this at home. Going from an equatorial to polar orbit uses an incredible amount of fuel.
Someone stated elsewhere in negating the possibility of a different type of vehicle providing supplies that said vehicle was incapable of achieving the shuttle's orbit.
Could the shuttle change orbit downward to meet up with a vehicle that itself was otherwise incapable of reaching the shuttle's particular orbit, or is that just as hard of a change? I'll have to fire up KSP, but would it be possible to meet a supply vehicle and use less fuel than an ISS rendezvous?
This is not about changing orbital radius, these are relatively cheap to change. It's about changing orbital plane - for 90 degree change (i.e. polar to equatorial) roughly speaking it would require 1.4 amount of fuel to get to the orbit in the first place (and additional fuel to get this fuel to orbit).
I've often wondered if there was some repair the Columbia crew could have done. Anything that the hole could have been stuffed with? What about pulling a tile off of a less critical section, shaping it, and putting it in the hole?
Post-Columbia there was some examination of repair options that could have been used if the crew had known about the damage. Some engineers considered it feasible to repair the hole in the wing using material scavenged from Columbia [1] but this was apparently considered very high-risk. The shuttle re-entered at Mach 25 and the leading-edges of the wings were made from titanium because of the extreme thermal and aerodynamic stresses they were subject to, so stuffing a tile (assuming it could be removed, which would have been unlikely) into the hole wouldn't have helped at all.
Some repair techniques and tools were developed part of the process of returning the shuttle fleet to flight after the loss of Columbia. These included a caulk-gun to allow in-situ repairs to thermal tiles [2] and a device for plugging holes in leading surfaces such as the wings. These were tested in space but were never needed.
An interesting article. I wonder what tools the crew had available for working metal. Even hand tools would suffice, given the 30 days to work on it. The idea of holding things in place with ice doesn't seem viable to me, ice would melt really fast. I'd go for screws, rivets, bending and hammering, etc., to get a mechanical connection.
Basically, just pile on enough metal so that there'll be just enough left as the rest of it burned away.
I was wondering about repairs the whole time I read that article. It's fun to think about sending up a rescue vehicle, but I would think attempting repairs would be easier and that wasn't really talked about in the article.
Not even close. The ISS is not a vehicle, it only has a limited amount of fuel for boosting its orbit. And even another spacecraft in the ISS orbit would take a vast amount of fuel to match altitude and inclination of the shuttle orbit.
I'd imagine that's pretty unlikely. They don't move it around much, just raise its orbit occasionally, and it gets regular visits from cargo ships so they don't need to keep large supplies of fuel onboard. Its much larger mass would be an issue, too.
Plane changes at higher orbits cost less. In fact, one of the ways to do them cheaper is to burn fuel to raise the apogee, plane change, then burn back.
The reality would be that if people knew of the extreme threat to life which existed, they would look to leaders such as the President and NASA to show they valued that life.
While in a military command and control situation it 'makes sense' to say these people are already lost, we just abandon them and move on, that would not be acceptable to the general public as that's not how things are perceived.
Indeed, it would almost certainly destroy the ability of NASA to continue if they were seen to be so impotent and incapable of doing anything when things go wrong.
A dramatic, high risk rescue attempt would possibly be the only option, even if that itself ended in disaster and death of all involved (a real risk according to the theoretical plan).
I think the public would have been more at ease knowing that a real rescue attempt was made and that genuine heroes had made the ultimate sacrifice in an attempt to save their colleages. People are all mushy and emotional like that.
Would it have made sense in terms of risk assessment, as a direct risk-reward evaluation ? Clearly not. But it's not always about that.
Besides, this is an alternative time-line scenario which never was. Those always have the benefit of working just like in feel-good Hollywood movies.
The CAIB asked for options for a hypothetical scenario. They were given options for a hypothetical scenario. It's unknown whether anyone would have had the guts to actually try to do it if the opportunity arose. Furthermore, sacrifice for the sake of rescue is one of the better aspects of humanity that is respected. Otherwise, all risky rescue missions should not happen.
A large part of the CAIB's asking will have been based upon the question of, "could NASA have done more to avoid the fatalities, after the issue had arisen?". If the conclusion of the hypothetical scenario was they could not have launched another craft in time, then it is obvious that, even had NASA known the extent of the damage of Columbia, they would have had no means to bring the crew back safely (though, of course, an Atlantis-based rescue mission wouldn't, per-se, be any safer, because Atlantis could easily fall foul of the same issue Columbia had).
The importance of designing the rescue plan was not simply wishful thinking, but to prevent future disasters. After Columbia, a rescue mission was planned alongside each shuttle launch in case this happened again (it didn't).
They surely made a mistake, but I don't believe it is what you are accusing them of here.
They had a long history of debris strikes in previous launches. They did not know that there was catastrophic damage to the wing's heat shield. They noticed the strike after the shuttle was in orbit. They elected not to disrupt the schedule of the crew or request additional observation resources (i.e. ground telescopes) to inspect it, and instead, they did some mathematics modeling of the strike which ended up being inconclusive, so they chose not to spend more time and money investigate further.
That is not the same as thinking they knew there was a problem and the astronauts were doomed but they decided not to even bother trying to rescue them.
A lot of the "didn't even try" is buried in your "elected not to" phrasing. Yes, they didn't check out the damage visually, which is another way of saying they didn't even try to assess the damage. At least part of that decision seems to have been driven by the fatalistic idea that a rescue was impossible and so it didn't really matter.
Also, I reach the opposite conclusion you do from "a long history of debris strikes". To me, this says that they absolutely knew there was a problem, and had known it for a very long time, but merely got used to it and dismissed it due to the ridiculous idea that it's OK to ignore if it hasn't killed anybody in the past. That history makes them look worse, not better. Same thing happened with Challenger and the O-ring leaks. The leaks were a serious problem and smart people said as much, but the concerns were dismissed on the basis that previous flights hadn't exploded so the leaks must not be serious.
Agreed. From wikipedia - "Engineers made three separate requests for Department of Defense (DOD) imaging of the shuttle in orbit to more precisely determine damage. While the images were not guaranteed to show the damage, the capability existed for imaging of sufficient resolution to provide meaningful examination. NASA management did not honor the requests and in some cases intervened to stop the DOD from assisting."
Judging from the article, a rescue mission of the kind described here would have effectively been impossible. Even getting to the point where it seemed like a good idea to try would have, in the overwhelming probability, still ended with the loss of at least one shuttle and its crew.
Lack of energy budget. You should read the article. It's a good story.
"Columbia's 39 degree orbital inclination could not have been altered to the ISS 51.6 degree inclination without approximately 12,600 ft/sec of translational capability. Columbia had 448 ft/sec of propellant available."
Columbia had 3% of the propellant needed in order to get to the ISS - the article says that sometimes to execute a plane change it may take more than the energy needed to get an object into space in the first place.
Nitpick (that doesn't change your conclusion at all): they had 3% of the delta-v needed to get to the ISS. Fuel requirements increase exponentially with delta-v, so it was actually way less than 3% of the required fuel.
THE ORBITER “RAN INTO” THE FOAM “How could a lightweight piece of foam travel so fast and hit the wing at 545 miles per hour?” Just prior to separating from the External Tank, the foam was traveling with the Shuttle stack at about 1,568 mph (2,300 feet per second). Visual evidence shows that the foam de- bris impacted the wing approximately 0.161 seconds after separating from the External Tank. In that time, the velocity of the foam debris slowed from 1,568 mph to about 1,022 mph (1,500 feet per second). Therefore, the Orbiter hit the foam with a relative velocity of about 545 mph (800 feet per second). In essence, the foam debris slowed down and the Orbiter did not, so the Orbiter ran into the foam. The foam slowed down rapidly because such low-density objects have low ballistic coefficients, which means their speed rapidly decreases when they lose their means of propulsion.