NASA Decides No Fix Needed for Endeavor's Tiles

bhmit1 writes "It looks like NASA is reporting that no repairs are needed for Endeavor. 'After meeting for five hours, mission managers opted Thursday night against any risky spacewalk repairs, after receiving the results of one final thermal test. The massive amount of data indicated Endeavor would suffer no serious structural damage during next week's re-entry. Their worry was not that Endeavor might be destroyed and its seven astronauts killed in a replay of the Columbia disaster — the gouge is too small to be catastrophic. They were concerned that the heat of re-entry could weaken the shuttle's aluminum frame at the damaged spot and result in lengthy post-flight repairs.'"

Comments

I'm glad I don't have to make these calls

[ExE122]

Their worry was not that Endeavor might be destroyed and its seven astronauts killed in a replay of the Columbia disaster -- the gouge is too small to be catastrophic. They were concerned that the heat of re-entry could weaken the shuttle's aluminum frame at the damaged spot and result in lengthy post-flight repairs

And I'm sure thats the only thing the astronauts were worried about as well... the precious shuttle.

It reminds me of a while back when a friend of mine called his mother to tell her he had a few drinks and was gonna stay the night at a friend's house. Her response was, "Yeah, I wouldn't want anything to happen to the car."

Regardless, I admire their fortitude given the history of the Columbia and all that has happened. I hope everything goes well and they get home safely.

--
Captialism: When it uses the carrot, it's called democracy. When it uses the stick, it's called facism.

Re:I'm glad I don't have to make these calls

[ExE122]

NASA haven't panicked and issued all kinds of worrying proclamations when it wasn't worried in the past: why start now?

Because they weren't all that worried about Columbia either. Seven astronauts died because of that.

Don't get me wrong, I see what you're saying. The damage may indeed be comparable to previous missions that went off without a hitch. And it is true, all of the lab tests show no cause for concern. But as another poster mentioned below, all the lab tests in the world can't make up for a real world scenario. The real world always has another trick up it's sleeve.

And you also need to realize that NASA needs to be extra cautious. A repeat of the Columbia disaster would raise some serious concerns about their credibility and may be detrimental to the future of space exploration in general.

--
Capitalism: When it uses the carrot, it's called democracy. When it uses the stick, it's called facism.

Re:I'm glad I don't have to make these calls

[Vellmont]

And I'm sure thats the only thing the astronauts were worried about as well... the precious shuttle.
If the only thing mission control was worried about was "the precious shuttle", then they would have just sent them out right away to fix the gouge.

Spacewalks are potentially dangerous. Micro-meteorites could tear right through a spacesuit and instantly kill an astronaut. They aren't taken lightly and are always judged whether the benefits justify the risks. In this case, they didn't.

Re:I'm glad I don't have to make these calls

[vought]

IMHO if something happens during a space walk, You still can bring the astronaut back on board, and still can try an unrepaired re-entry. But even if the repairing astronaut dies (which is very unlikely), the others are still alive. And what if the astronaut perched at the end of a 100-foot boom crashes into the tiles he's repairing, damaging them more extensively, or even beyond repair? After all, the arm is very heavy and the EVA suit is 300 pounds, along with the 200lb astronaut inside of it. That's a lot of mass to be swinging around next to all the other, undamaged tiles.

Or what if the 'goop', applied unevenly, causes a hot spot on another tile? Right now, the damaged tiles are located over a wing spar - the thickest structural part of the wing, and a section that can take more heating. Since the depth of the gouge indicates that the plasma flow over it will 'eddy' over the deepest area, keeping it from the greatest heat of reentry, models indicate that the aluminum structure of the shuttle won't fail, and that temperatures won't exceed 350f.

The problem with speculating on NASA decisions, as so many coffee urn quarterbacks are doing this morning, is that they really have no idea how complex the shuttle and its mission really are. The items I've outlined here, available in almost no major news stories about the decision, were easily obtained at NASA Tv and Aviation week - and they're a small sample of the factors in this decision.

Re:I'm glad I don't have to make these calls

[Ellis D. Tripp]

>>Because they weren't all that worried about Columbia either. Seven astronauts died because of that.

In all fairness, nobody at NASA knew the extent of the damage to Columbia prior to reentry. There were engineers who suspected that there might be some, and wanted photography to be sure, which NASA disallowed. If the existence of a large hole in the leading edge of the wing was known, some type of rescue operation could possibly have been put into place, as there was no repair possibility at that time.

In this case, NASA had detailed imagery of the damaged area several days before the return. That allowed for detailed analysis and laboratory testing, which have apparently convinced NASA that the extent of damage is limited enough that no repairs are required prior to reentry.

I would like to know what assumptions were used in making the "no repair" decision, nonetheless. It would seem to me that even if the damage was not severe enough to REQUIRE the repair, this situation provided a chance to test out the newly developed repair techniques and materials in a "real world" setting, allowing engineers and future crews to gain more confidence in the repairs if and when they are required on a future mission. Is the risk of an EVA/repair causing further damage really high enough to justify throwing away what could be a very valuable "learning experience"?

Re:I'm glad I don't have to make these calls

[couchslug]

"And you also need to realize that NASA needs to be extra cautious. A repeat of the Columbia disaster would raise some serious concerns about their credibility and may be detrimental to the future of space exploration in general."

They don't care enough about space exploration to halt the use of old systems like the Shuttle, continue exploration with unmanned systems, then send meat into space with more mature technology.
This isn't 1492, and we are under no pressure to send crews off in the modern equivalent of a wooden ship. We can learn and observe and manipulate with unmanned systems that have a much more rapid rate of evolution than that of man-constrained systems. If we want humans to see the process we can record it.
If an unmanned system is lost we don't have to deal with the hysteria that the public expectation of zero casualties engenders. (Good thing we didn't expect zero casualties in the era of test pilots, or aviation would not have gotten very far.)

Re:I'm glad I don't have to make these calls

[networkBoy]

Actually, their primary concern was the EVA its self. The suits are showing possible signs of aging (a 2 inch tear in the top two layers of a glove on the last EVA). They don't want an astronaut to be at risk of decompression while attempting a repair that is not life threatening.
-nB

Re:I'm glad I don't have to make these calls

[zippthorne]

It is unlikely that a rescue would have been possible. It would've required extreme fast-tracking of one of the other shuttles, which NASA has proven to be unable to do. While I was living in FL, I think there was maybe one launch that went up at the original scheduled time, many were postponed, and the vast majority ended up postponed to over a week later.

The disappointing thing about Columbia however, is that knowing no rescue or repair would be possible they decided additional imaging was unnecessary: The astronauts' fates were already decided, so why bother getting some pictures? It would have been nice, for the investigation later, to have such images. Even if they had landed safely. It's doubly disappointing because it seems DoD chose not to take images of their own initiative, either. It would've made a good training exercise even if the data itself turned out to ultimately be useless.

At the time, it felt to me that the decision not to take or ask for pictures was akin to the ancient sailor's superstition against learning to swim.

Re:I'm glad I don't have to make these calls

[rbanffy]

"(Good thing we didn't expect zero casualties in the era of test pilots, or aviation would not have gotten very far.)"

What bothers me isn't that there are people taking risks to advance our knowledge. What bothers me is that they are taking risks to prevent advancing our knowledge.

It took more than 100 flights and the loss of a ship with its crew to make NASA start looking at what happens to a shuttle during launch.

It's one thing when people die because you couldn't foresee a problem in a new wing design or a new engine technology. It's something entirely different when people die when you are unwilling to foot the bill of an EVA to inspect the spaceship while in orbit. It should have been done on the first flight of the Columbia (it wasn't possible at the time - no MMU, two crewmen). It should have been done when they decided to get rid of the white paint for the main tank. The belly inspection should have been conducted on the first time the shuttle docked with Mir. It was inexcusable not to do it as soon as the MMU became available and the shuttle started making regular trips to the ISS.

There is a lot wrong in this.

A chance for testing lost

[Chairboy]

It's unfortunate, this could have been a good test case to see how the repair materials/procedures work under realistic conditions.

Having firm, experimental data about:

* The process of applying the patch
* How well the patch stands up to re-entry
* How well the patch protects underlying systems

and more. Better to get this data on a 'non-critical' bit of damage than waiting until something is REALLY busted before finding the inadequecy.

They've done extensive testing on the ground, I'm sure, but a real-world test scenario can trump ten lab extrapolations. That's why we do external betas of software, the real world always has something up it's sleeve.

Re:A chance for testing lost

[RoverDaddy]

But most betas don't run the risk of killing 7 people. There are serious risks involved in -doing- the patch too.

Re:A chance for testing lost

[pilgrim23]

The tiles are extremely delicate. NASA viewed a lumbering astronaut in a suit ill designed for delicate work, with a tube of superglue and a squeege in the area around the main heat shield of the Shuttle a far greater threat then the small hole.

Re:A chance for testing lost

[RoverDaddy]

The Astronauts -have- practiced patching tiles in the cargo bay. But those tiles can't be on the outside of the shuttle during reentry.
While I was writing my previous response I thought about the idea of 'pre-patching' some tiles near the rear of the shuttle before launch, in order to see how well those tiles did on reentry. Can you imagine the outcry if NASA suggested purposely -damaging- a few 'unimportant tiles' before the mission even begins? And I doubt you can easily add a few spare tiles to the airframe of the shuttle - just ain't gonna happen.

infamous powerpoint presentation

[pimpimpim]

Let's just hope they did't reuse their previous powerpoint presentation on the space shuttle as a template for this meeting.

Now that link is a bit of a read, but a very striking introduction on influencing decision-making with presentation techniques, even if this costs other people's lives.

NASA needs to get out of the media black hole

[Anonymous Coward]

...or the shuttle's days will be numbered even if it is still a useful tool.

Endeavour is currently on the sixth shuttle mission since Columbia was lost. On Slashdot there's a chance that somebody could tell you what was achieved on any of those six missions. Ask an average member of the public though, and I guarantee you that less than 1% have any idea of a single piece of scientific research achieved on any of those six flights.

A large number of those members of the public will be able to tell you about the scares over foam and tiles on every single mission though - because that is the only part of shuttle missions that the media cares about.

This is only going to be fixed one way. NASA has to start giving out copious quantities of interesting video from shuttle flights to the media, and completely seal away from the media any talk of damage or problems. The damage has been of no real significance every time, but it is the only thing we're talking about.

Unless NASA can extricate itself from the media black hole, it will never again run a shuttle mission without the shuttle being called into question - and that will eventually lead to calls for funding for this "dangerous" vehicle to be withdrawn. After all, it doesn't actually do anything when it is up there, right?

IANAAE

[Stanistani]

Here's where we get to watch a lot of folks decide whether to comment on the effects of something outside of their experience and expertise.

I've seen photos and 3D imaging of the bashed tiles. I know very little of the forces involved. I have seen no structural analysis of the materials that are beneath the deepest part of the gouge.

To a limited extent, I can compare this damage to the past damaged tiles. There seem to have been a number of similar damaged tiles in the past, and those flights landed safely.

The astronauts could slap some of that goop on the gouge, but risk damaging the tiles by accident, or changing the aerodynamics of the craft.

There are many unknowns. I really don't know what will happen when Endeavour reenters.

I wish them well, and hope that NASA can complete the remaining shuttle flights without mishap.

Hey, NASA, here's an idea...

[WED Fan]

As a former USAF avionics specialist and later crew chief, one thing was always true:

The decision about air-worthiness, mission-worthiness was the pilot's, the aircraft commander.

It didn't matter if I told him that sure, the plane will fly, if he didn't like it, the plane didn't fly.

So, NASA, provide all the information to the commander, pilot, and crew, and let THEM make the call. If you don't like what they decide, it can be taken up AFTER the mission.

Re:Hey, NASA, here's an idea...

[Billosaur]

But that's the difference between an aircraft and a spacecraft -- an aircraft pilot can look his plane over, read up on the maintenance, talk to his ground crew and then decide to fly or not. In NASA, it works differently. A Space Shuttle commander has command of the spacecraft, but Mission Control in Houston has command of the mission. You have to remember: the crew of the Shuttle can't just go bombing around in Earth orbit like they are flying the Millennium Falcon. Every move has to be choreographed and planned out months and even years in advance. When unexpected problems crop up, the technicians on the ground certainly know more about the workings of the machine than the crew, as they have all the data at the fingertips, they are experts in their systems, and they can draw on contractor resources to get more information. Decisions like this cannot be left to the spacecraft commander; his/her job is hard enough without having to keep in their head the compendious amount of information regarding their spacecraft.

It has been this way since Mercury; it was Chris Kraft who outlined the need for the ground to have the skills required to manage the mission and deal with problems in real time, so that the crew could concentrate on their activities in space. The system has worked extremely well over all these years, with the exception of the Columbia accident. I for one am confident that NASA knows what it is doing and will take all the precautions it can before Endeavour is allowed to land.

Re:Hey, NASA, here's an idea...

[everphilski]

Fly it home, unfixed is what Houston has ordered. Hopefully the man who made decision has signed his name to it.

The decision is by committee. The consensus to fly home was made last night and was unanimous among the committee. They did extensive analysis both with CFD, analytical models and arc jet testing.

They do have procedures, and materials. Since the last disaster, they have sent up patch kits. If its not adequate, they can send up one that is on the next go round. They chose not to patch because they don't like the risks involved with an EVA (to both man and machine).

Precisely. If they banged up a few tiles doing the repairs and wound up stranded in space, dying, that would be a true tragedy when in reality no repair was needed. The tiles are located on the aft midsection of the belly of the orbiter which does not receive extreme reentry heating. In fact they don't get over 400 degrees and the aluminum underneath stays 50 degrees under design temperature, and is still covered by Nomex (a flame retardant, among other things used by fire fighters) (still in place, as best we can tell). (I am an aerothermodynamist, not working shuttle but working closely with shuttle people)

Do you have a source on your Soyuz data? I'd be interested in seeing it. What I've heard and seen is that production as of late has slowed down to the rate of demand, IE, there isn't more than one on hand. But I could be wrong and I'd be interested in seeing a source that says so.

One final test

[ubrgeek]

> after receiving the results of one final thermal test

While playing Stairway to Heaven, bic lighters were waved back and forth over the affected area.

Re:Disaster waiting to happen

[TheMeuge]

Life has a cost too.

We seem to have forgotten that in the U.S. lately. Granted, the integrity of the shuttle frame is not worth human life, but the panicked semi-troll responses to this crisis made me realize yet again how far we've fallen as a society.

The same people are "concerned" now, as the ones who were calling for ending the space program after Columbia.

We are so fat and content that we seem to think that anything that interferes with our blissful lives must be a curse. We have forgotten the drive and determination of scientists, engineers, and many others, which made the world we're living in possible. Make no mistake about it - without self-sacrifice, many of the technological and scientific developments that shaped the latter half of the 20th century would not have been possible.

Yet the population, spurred on by the scaremongering media, seem to think that we've now magically gotten to a point at which we can make everything safe. Well... we almost can... if we all just stay home. But if we want another revolution in the development of our species, like the one that spanned 1850-1975, we will have to accept that some things are worth it. Yes, it's important to minimize risk... but sometimes you have to accept a reasonable amount of risk, take a deep breath, and just go.

Anyway, sorry about the rant...

Memo to all NASA employees:

[Ed_1024]

Subj: Space Shuttle

However tempting it may be, given the considerable savings, please don't source any more tiles from "Home Depot".

NASA Mgmt.

Re:To err on the side of caution...

[bev_tech_rob]

It would be problematic to replace the affected tiles.....if I remember from old articles (don't have links, sorry), each tile is unique and not the same size as its neighbor (although they visually appear to be). You would have to grind it or somehow alter the shape to make it fit the hole precisely as it should.

If they used the caulk, I would worry about the goop bubbling out or not being flush with the surrounding surface, thereby creating drag which may pull the whole tile out, which would leave a BIGGER opening with sharp edges causing more tiles to be torn off...I would think the black paint they were discussing wouldn't hurt.....just my .02 cents...

Re:To err on the side of caution...

[RoverDaddy]

I read Osheroff's quote and decided he's talking out his ass (or it's a lousy quote). Perhaps successful repairs can only increase their chances, but things can and do go wrong, and it wasn't explained how Osheroff was in a better position to make the analysis than the people at NASA doing it. BTW, if you read the article carefully, it seems that financial considerations would lean toward doing the repair, not avoiding it. Leaving the gouge in place may result in more down-time and repair work for Endeavour on the ground.

If it aint [all that] broke, don't fix it.

[reality-bytes]

They can't actually replace entire tiles on orbit. They have a 'patching' system which allows them to spread a compound into any nicks in the tiles.

Now, the compound has to be applied by an astronaut attached to a long extension arm attached to the Shuttle's robotic arm. When they tested this a few flights ago, it became readily apparent that it was at best difficult to work this way. The length of the arm caused significant 'bouncing' with every motion. At the time they only pulled a gap filler and simulated the motion of filling a tile and it wasn't easy.

The real danger is that the control issues of having a 'massive' astronaut + EVA gear swinging around on the end of that very long arm so close to the TPS could actually cause more damage to the tiles than it fixed.

Furthermore, the compound could actually cause even worse localised heating issues on re-entry depending on how well it fills the tile ie: It could cause ducting etc.

Re:To err on the side of caution...

[east coast]

but we know that spacewalks occur all the time routinely.

What's risky about this isn't the space walk itself but the concept of damaging more tiles. It's a delicate operation and one slip can make things go from bad to worse easily.

Perhaps there is a financial motivation for not carrying out the repair?

What financial motivation? The material already exist onboard. There is no investment and the amounts by which NASA would be set back in the case of a mid-air breakup or even a safe landing with an unusable shuttle far outweighs using the patch method. If you're going to say something like this I'd think that you'd need to back it up with some logic (even if it's faulty) or fall suspect to producing FUD. Not to be a dick but I find it to be a dismissive remark that borders on trollish.

What I'd like to see is an actual breakdown of the possible positive and negative consequences of each course of action and the probabilities that NASA has assigned to the outcomes. I'm really hoping that they've put some serious statistical analysis into this decision and aren't just flying by the seat of their pants.

Again, not to be a dick but I'd like to give the guys at NASA some credit here and pretty much chalk this up to random speculation of a problem that has been reviewed by NASA's best engineers for hundreds, if not thousands, of man hours. A PDF with some stats is not going to convey the experience of the teams in question. I know we joke that NASA has certain problems that are rather embarrassing but I'd like to think they went the extra mile on this one.

Certainly, the article quotes a Nobel Prize-winning physicist, Douglas Osheroff, as saying that the repairs "can only increase their chances of making it down."

Let's requote that: the [successful] repairs "can only increase their chances of making it down."

Again, I think it's a matter of potentially doing more harm then good. I think if NASA had a guarantee from the mouth of God that this repair would not cause more damage they'd go for it in a second. They'd be fools not to. This isn't a question of if the repairs will help but a question of pros and cons.

I'm not going to say that everything is going to work out but I certainly hope they do. If I were up there I'd be more willing to trust the ground engineers at this point. Not to say that Dr. Osheroff doesn't know what he's talking about, he's well versed on the subject but I don't know how much he really knows about this incident and what his take is on the chances of making the situation worse with a potentially botched repair job.

Not even Duct tape?!

[erroneus]

Man, that pretty much fixes everything... did they forget to pack any this trip?

Re:Why not change the design?

[ahuard]

The feather reentry technique is only useful at suborbital speeds. How do you expect the spacecraft to slow down to these speeds? The only option is to use the underside of the shuttle as a heat shield as it is barreling through our atmosphere. What other options are there? You can't use a fuel burn because that would enormously increase the launch weight, and therefore the cost, of every mission. The shuttle was designed by some of the best aerospace engineers in the world. I'm sure every crazy reentry option was on the table during the design phase and they chose the one best suited for the job.

~Andrew

Meteroid speed

[Rob T Firefly]

Couldn't they just create some type of shield such as teflon or some other strong material to be placed a short distance from them covering their backs? I would assume that the spacecraft covers their front. The faster meteoroids might be travelling at roughly 30-40 km/sec. (*) In comparison, here on Earth the fastest bullets cruise at around 1.2 km/sec, with slower bullets loping about in the neighborhood of 0.3 to 0.6 km/sec. (*)

All the strong layers of whatever you want to strap onto an astronaut in addition to all the crap s/he's already got to wear and maneuver through won't help all that much against a small particle moving at that speed.

Re:A bit of Tile prediction History: all bad

[Eponymous Bastard]

Which is why they are not relying on calculations. They actually grabbed some tiles, gouged them in the exact same form from the measurements taken in orbit and then put them in a hot wind tunnel (The Arcjet facility) to check what will actually happen
see here
And:
here (with pictures).

The tests at Arc Jet used a set of tiles, with identical damage drilled on to a test article. This was then put through the heat of a simulated re-entry, to test how the damaged area performed, along with the gathering of thermal data.

'The Arc Jet test using the damaged test article was completed, initial assessment did not identify structural burn through,' noted one encouraging memo, with data showing that the heating remained 50 degrees below the baseline requirement for the underlying structure.

And those articles are from the preliminary results. They were supposed to do an additional test with the repaired tile.

Why do we send people into space?

[Leuf]

Isn't the whole justification for manned missions that people can react and do a lot more than robots, at least at this point in time? And yet we're afraid to let them out the door to actually do anything. Time and again when people are given the chance to perform they rise to the occasion and exceed expectations.

Remind me, how many astronauts have we lost on spacewalks?

Re:To err on the side of caution...

[Volante3192]

The HRSI tiles are made of a low-density, high-purity silica 99.8-percent amorphous fiber (fibers derived from common sand, 1 to 2 mils thick) insulation that is made rigid by ceramic bonding. Because 90 percent of the tile is void and the remaining 10 percent is material, the tile weighs approximately 9 pounds per cubic foot.

http://science.ksc.nasa.gov/shuttle/technology/sts -newsref/sts_sys.html

My structural physics knowledge is a bit lacking, but something made of 10% rigid fibre 1-2mm thick and 90% void doesn't sound like the sturdiest structure to be applying force to.

I'm trying to think of a similar, down to earth item that mimics that structure...but best I can come up with would be like packing peanuts. Close, but it's not rigid enough.

Re:same moron with mod points again

[posterlogo]

Your comment is off topic (as is mine, probably). I hope your whole thread gets modded down to obscurity. Stop whining about mod points.

Re:To err on the side of caution...

[sremick]

Actually, they are quite delicate. I know, because I've got a piece of the material. And no, I'm no one special... they sell it (or used to) in the KSC gift shop. A tap won't "snap" it but it will crush that spot... these things are like a silica sponge, mostly air. Great insulators, at the expense of being extremely fragile. It can't take much of a bump without damage.

I managed to easily put some marks into my sample before I smartened up and kept it in its case.

Re:Disaster waiting to happen

[Chris Burke]

Well it's not offensive when you put it like that, but it's still not right. They are still considering the lives the astronauts at the expense of the shuttle. Their analysis and simulation said that with the present damage the worst that will happen is that the shuttle's wing might be damaged and require lengthy, expensive repairs on the ground. That's the money angle. They could try to patch the damage and prevent this, but EVA is dangerous and these repairs are difficult, if it ends up causing more damage to the delicate tiles then all the astronauts' lives are in danger. On-the ground repairs, no matter how expensive, are a better option.