Images of Endeavour's Damaged Tiles 331
Roland Piquepaille writes "Neptec Design Group, a Canadian company and a NASA prime contractor for 25 space missions, was kind enough to send me exclusive images of Endeavour's damaged tiles during its last take-off. So here are some of these pictures" The pictures are pretty amazing and make the urgency of this whole thing much more amazing.
How long has this been happening? (Score:5, Interesting)
Is it so urgent? (Score:3, Interesting)
Leave Endeavour in orbit. Compared to the big-mother boosters, the shuttle itself does not require a lot of fuel, and given the smaller size of the next-generation craft we're looking at, I could see a use for a "space truck" the size of Endeavour, even after the shuttle program does out the door.
Just send up something else to bring them home.
Re:Is it so urgent? (Score:2, Interesting)
IIRC it is rated for week or two at the most.
Without a scale... (Score:4, Interesting)
I've heard on the radio that they are discussing a roughly 3" scrape....which, if scaled to the longest axis, is objectively pretty small, but when considered against the turbulence, heat, and pressure that those belly tiles are faced with? It looks huge and devastating again.
Those astronauts have balls of steel if they ride that thing down again.
Re:How long has this been happening? (Score:5, Interesting)
Most of the shuttle is not under the same level of thermal load as the front edges of the wings during re-entry. Columbia got unlucky that the damage was at the worst possible spot.
Its a bad design, but the whole shuttle is an awful design. Most of the time it works, though.
IMO, this is a reaction to Columbia and a dramatically reduced interest in the shuttle program. For ten years launches barely got reported. Its nice (for the continuance of the shuttle program) for people to be talking about it.
Plus, for those who haven't seen a shuttle tile up close, they're not very big. Thats not a six inch gash in there.
Ol' Bricks and Wings (Score:3, Interesting)
It's sad that we have to do this on EVERY launch when we had developed a perfectly good system where the heat shield was covered for the entire time it wasn't in use.
What, precisely, was wrong with the capsule system that necessitated the development of something that can *gasp* glide to a landing? How have we saved money by building a reusable craft when it costs a billion dollars a launch?
Re:Ol' Bricks and Wings (Score:3, Interesting)
Size, risk, recovery costs. Well, when you calculate the cost of a single use capsule that can make deliveries to the Space Station, launch satellite, used to repair satellites, THEN you can do a cost analysis. Saying we have or have not 'lost' money compared to some non-existent thing, or that using a capsule wouldn't have cost more lives is a logical fallacy.
Re:wrong (Score:4, Interesting)
You can't ignore air resistance at low altitudes (the impact happened in the first 2 minutes) at supersonic speeds! Acceleration due to gravity is negligible due to the timeframe, we are talking fractions of a second. So for similarly shaped pieces, the drag force will be similar. The lighter piece, foam being much lighter than ice, will slow down very quickly. Now we approach the shuttle which has not slowed down. We have a large speed differential between the foam and the shuttle, whereas between the ice and the shuttle, there is very little speed difference.
Re:How long has this been happening? (Score:5, Interesting)
The shuttle design (and the program) is one set of bad decisions after another made for corporate welfare and political reasons shoehorned through Congress based on a huge number of known lies (like the shuttle-launch-a-week they claimed they'd have). It was continued as a way of getting to the Space Station, even though the construction of it was delayed 15 years.
There were dramatically better designs considered during the 70s that would've been cheaper and more reliable, but wouldn't impact various Senator's home states as much. There were bad decisions made even after the Shuttle was picked (using aluminum skin not titanium, which is why the heat shield is needed anyway).
Seriously. Read some histories of the shuttle program. You'll learn why it happened and not the Apollo-based Mars mission, why the Saturn V (and future solid fuel boosted versions) were dropped in favor of a much more expensive per pound STS.
NASA has smart engineers. Thats why the design for the shuttle's replacement looks nothing like the shuttle. Its also a big reason why the Buran was killed in the USSR, and the Soviets/Russians dominated manned space flight for 25 years.
... and built by the lowest bidder (original?) (Score:5, Interesting)
"When reporters asked Shepard what he thought about as he sat atop the Redstone rocket, waiting for liftoff, he had replied, 'The fact that every part of this ship was built by the low bidder.'"
"I felt about as good as anybody would, sitting in a capsule on top of a rocket that were both built by the lowest bidder." (Senator John Glenn, Colonel USMC, Retired)
"It's a very sobering feeling to be up in space and realize that one's safety factor was determined by the lowest bidder on a government contract." -- Alan Shepard.
Re:How long has this been happening? (Score:4, Interesting)
Hence you have the bloated obsolete pig we use today.
Re:Err on the side of caution...don't you think? (Score:5, Interesting)
First and foremost - if there is a small chance of catastrophic loss of vehicle, then measures should be taken to prevent that.
But Secondly - and possibly more importantly; how many more shuttle flights will there be? What if there is more serious damage on the next flight? And we still have never tested the repair techniques?
I think that this damage is a perfect opportunity for NASA to do what it does best: testing new aerospace technologies - and in this case, repair of shuttle heat-shield damage. The repair job will be a great opportunity to learn new EVA skills and techniques. After the shuttle is safely down, the repair job can be studied, and evaluated for how it held up during re-entry, and I think that is valuable science that wouldn't otherwise be done.
To *not* repair this damage, is short-sighted in two ways: It's hoping that the damage to Endeavor isn't fatal, and it's hoping that the next mission to get damaged, also does not require repairs, and if it does, that we will get the repair right the first time, when we've never ever done anything remotely like it before.
Re:How long has this been happening? (Score:5, Interesting)
Buran was dropped due to a lack of funds because of the collapse of the Soviet Union, which left their space program strapped for cash.
Although Buran was essentially a copy of the Shuttle, the Soviet engineers were able to surmise its shortcomings and address those issues. For starters, it wasn't as vulnerable to the mess we had with Columbia, and are having again with Endeavour.
The crew compartment was supposedly reinforced and structurally isolated from the rest of the ship, suggesting that a Challenger or Columbia type disaster could have been potentially survivable.
Buran was launched piggybacked on an Energia booster (which is the closest thing Russia had to a Saturn V) -- economies of scale suggest that this would have been cheaper in the long-run, not to mention that it kept a large multi-purpose launch vehicle in Russia's "arsenal", something which the US currently lacks (not to mention that an Energia could have sent up huge portions of the ISS in one go, rather than expensively constructing it bit by bit as we are doing now.
Buran could fly and land automnously. The space shuttle gained this ability only recently, and to my knowledge, it's never been attempted. This combined with the continuation of the Soyuz program hypothetically allows the crew to stay aboard Mir/ISS, and return via a Soyuz capsule, while the Shuttle lands on its own in the case that it was damaged during takeoff, and would be risky to land.
I wouldn't be terribly surprised if NASA uses a similar strategy to get the crew of Endeavour home.
It still wasn't a great idea all in all, but it made a hell of a lot more sense than the Shuttle does. Kliper [wikipedia.org] looks very promising at the moment, and may be a "best of both worlds" compromise between traditonal capsules and shuttle-type craft.
Re:How long has this been happening? (Score:3, Interesting)
Richard Feynmans report was pushed into the appendicies of the full report. Personally, I don't think it is dry, but to each his own.
Re:Err on the side of caution...don't you think? (Score:3, Interesting)
Honestly it could be fixed with a loss of payload capacity, put in an emergency ablative system in place, a set of mixture tanks and nozzles that when temperatures rise to dangerous levels fire and fill both wings with rapidly expanding foam that acts as an ablative firestop AND insulation to the rest of the structure. You might lose 15% of the wing but it will be structurally safe enough to get you to the ground. I believe they even looked at such a solution as well as the newer fireproof coatings used on buildings to protect the metal during an intense blaze(another ablative fire protection put as paint) to be applied inside the entire win structure.
Problem is, reducing the payload capacity is not an option.
Re:How long has this been happening? (Score:2, Interesting)
Buran could fly and land automnously. The space shuttle gained this ability only recently, and to my knowledge, it's never been attempted
One of my college professors actually worked on the guidance, navigation and control system for the shuttle program. From my conversations with him, the shuttle has always had an autoland capability, it was just the fact that none of the hot shot shuttle pilots wanted to be the first to not land manually.
Re:Direct link to the images. (Score:3, Interesting)
This isn't really an issue of insulation. It's the disturbance of laminar flow. The laminar boundary layer is actually quite a good insulator itself, especially at Mach 20. The main issue is how much the hole disturbs the boundary layer and what localized heating might result. This small of a hole in diameter, even though it's mostly through the tile, should be mostly negligible. But NASA is treating it VERY seriously and is doing simulations as well as has an arc-jet facility to test on an exact duplicate of the damage. (It's a 3D model of the hole, if you check the video, and is easily reproduced on the ground. It has even been printed out with a 3D printer.)
Remember that Columbia damage was on the Reinforced Carbon-Carbon (RCC) panels on the leading edge of the wing, not the tiles on the belly. The leading edge is one of the hottest and most critical points where that damage occurred. This damage is generally low risk, and EVA is always risky to some degree, but this might be a great opportunity to test repair procedures. When people talk about whether NASA is making decisions based on schedule for this damage, it's not about ignoring risks for the sake of schedule. Risk wins, easily. The schedule issue is that if the damage is not a risk at all, is it prudent to fix it anyway to test procedures and have an actual flow repair to analyze upon return. Remember, EVA and extending flights adds risk to the crew too, but can be beneficial and reduce risk both for this flight and future flights.
The reasoning of NASA engineers? (Score:2, Interesting)
A quick check on re-entry temperature variation on this site: http://www.columbiassacrifice.com/$D_temperature.
If NASA engineers feel these tiles can re-enter without repair, their reasons could be:
1) This area of the shuttle does not have to contend with the extreme heat that is experienced at the nose or other leading edge surfaces so the "hot air" isn't hot enough to melt the aluminum in the belly, and
2) The hole must be small enough that hot air flow may "skip" over it on re-entry. If the hot air can indeed passes right over it, then the danger to the aluminum inside is probably not very great.
If the engineers ran a "simplified" mathematical simulation assuming the hole was just the "average" well-formed hole, the above rationale would make sense.
I think the more important concern to focus on (which I'm sure NASA must have considered), is that this hole is very asymmetric. The photos provide terrific evidence. One side the gash slopes gently into the "hole" (I presume where the depth sensor reads 1.2 inches, since the tiles are only 1 inch thick), and on the other side, you have a quarter ping-pong ball cut-out as well as a 90-degree lip of half-tile above the hole. In this instance, I think the direction of travel of these tiles on re-entry matters a great deal... I think the first scenario below may be most cause for concern.
1) If the "up" orientation of the tile lettering is the shuttle's forward direction, I would imagine the hot air flow will not be turbulent upon entering the gash, and will actually follow the gentle slope downwards towards and into the hole, melting what is inside. What hot air doesn't make it into the hole will smack into the 90-degree lip and the quarter ping-pong ball cut-out, causing excess heat at those edges and/or loosening that tile from its backing, causing it to fall off (though not too likely since that lip represents only a small portion of that tile, and it is buttressed by the other tiles "behind" it).
2) On the other hand, if the forward direction was reversed, the hot air flow would become turbulent upon meeting the quarter ping-pong ball cut-out. If the dimensions of that cut-out are sufficiently disruptive, the turbulent hot air could "lick" the hole, melting whatever is inside, what doesn't go into the hole will glide off the sloped ceramic gouge on the other side. With the turbulent air, there will be a negative air pressure around that tile, but the force shouldn't be enough to rip the tile from its backing.
If the shuttle direction is that of option #1, let's hope that hole is small enough that as litte hot air gets in as possible.
My point is this: A hole is not just a hole unless it looks the same from all sides...
Re:How long has this been happening? (Score:3, Interesting)
It's true that the shuttle made subsequent repair missions easier. But to say that only the shuttle could have launched the missions listed above isn't.
Re:Where's the space? (Score:3, Interesting)
While I'm sure the holes in the tiles of the shuttle is not part of NASA's plan I think it's actually a very useful part of the mission.
We need to get beyond this whole concept of sending up the best and the brightest and throwing gobs of money at the program. We need to get to the point where we will have establishments (most likely lunar at first) where we're going to have real workers and not just high end engineers.
The idea of doing maintenance in space is going to be part of this future colonization. Being able to know how to do real work in this environment is going to bring us much closer to those goals. If we're yanking people out of a space station or colony every time the slightest maintenance needs done we're going to be paying big bucks with little return.
The lessons learned with the tiles on the shuttle and the heavy maintenance schedule of the Mir are going to take us a long way in establishing real working environments instead of just clean room type experiments.
Re:How long has this been happening? (Score:3, Interesting)
Vandenberg was ramped up to process Shuttle flights - they previously didn't even have ANY manned spaceflight capability at all. They built all that out. And Thiokol blew it.