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« The Genocide of Muslims | Main | A Heretical Thought »

To Repair Or Not To Repair?

Tariq Malik has a good story on the current state of the Shuttle tile issue.

Apparently, the concern is not for loss of the vehicle (and of course, the crew, but we have lots of astronauts*, and only three orbiters left). The concern is whether or not a repair will reduce the turnaround time for repair on the ground that's worth the risk (to both crew doing EVA and the vehicle, in the event they actually make things worse by dinging it somewhere else or botching the repair) of attempting to repair it.

I don't have access to all the data, but I'd be inclined to come in as is, assuming that it really doesn't risk vehicle loss.

Someone on a mailing list I'm on noted that they wouldn't want to be the person who signed off on a return without a repair. As I commented there, there are risks either way. If they attempt to repair it, and lose the vehicle on entry, it would be easy to second guess the decision, and decide after the fact that the repair caused the loss, whereas leaving it alone might have brought them home all right.

There are no risk-free decisions. Every action in life, every breath you take, is a gamble. It's just a matter of judging the odds.

[Friday morning update]

Sorry, Keith, but it wasn't a joke. It's a description of reality. I know that you have trouble with that sometimes.

[Monday morning update]

In rereading Keith's strange comment, I have no idea what he's talking about here:

...to make sure to get a link to a drunk astronaut story in the process.

The only story I linked (other than Tariq Malik's) to was one about Lisa Nowak, the main point of which was that NASA has too many astronauts. Reading is fundamental.




* Of course, the fact that we'd lose Barbara Morgan, the other "teacher in space" (quotes because she's officially an astronaut) would have dire PR effects.

Posted by Rand Simberg at August 16, 2007 02:09 PM
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Someone on a mailing list I'm on noted that they wouldn't want to be the person who signed off on a return without a repair.
Who in his right might would want to sign off on anything in this program ? There is basically no good way to run it, there are bad choices and extremely bad ones.

Posted by kert at August 16, 2007 02:20 PM

Rand, you got the argument right except for one aspect. The repair techniques are not fully certified, and so there is also a desire to use this opportunity as an impromptu DTO. Again, such a decision needs to weighed against the risk of crew. Fortunately, the DTO angle is being properly considered, which is to say that it didn't factor into the assessment of the damage or the EVA risk. It's just a note of opportunity.

Posted by Leland at August 16, 2007 03:32 PM

Yes, it would be a useful Development Technology Objective (DTO), but not sufficiently so as to justify the risk, given that this will probably not be the TPS of choice for future systems.

Posted by Rand Simberg at August 16, 2007 04:05 PM

I dunno Rand, I'm actually am for using tiles on the backshell of CEV. The real difference is that the TPS won't be sitting next to a large tank that rains all sorts of debris on it. Not arguing the entire merits of Ares or NASA, but putting the return vehicle on top of the stack is a major improvement to TPS. Add the launch abort system skirt protecting the tile through much of the ascent and the SM protecting the heat shield until entry, I think you are fine with tile (not counting higher heat loads for the heat shield for a lunar return).

Posted by Leland at August 16, 2007 04:46 PM

I dunno Rand, I'm actually am for using tiles on the backshell of CEV. The real difference is that the TPS won't be sitting next to a large tank that rains all sorts of debris on it.

If your only criterion is safety, then I agree. But it's not.

Posted by Rand Simberg at August 16, 2007 04:53 PM

Well, that should be my perspective ;)

Posted by Leland at August 16, 2007 05:07 PM

A decision is made: fly home as is.

Posted by Leland at August 16, 2007 06:58 PM

The sad part is that all this uncertainty could
have been avoided if NASA had a correlation
program from the beginning... had they made it
an early priority, they could have built a
database of how much of a scratch on the way
up would result in how much heat damage on the
way down... but it seems that they didn't even
think of trying to inspect of the as-launched
condition of the TPS on orbit until after the
Columbia accident.

-dw

Posted by dave w at August 16, 2007 10:00 PM

I just read Keith Cowing's hyperventilation over your pragmatic take on things. His skin has gotten very thin over the years, and it shows. Where he perceived a joke on your part, I had to look hard to find it.

Posted by J. Craig Beasley at August 17, 2007 06:51 AM

That must be a hard decision as to whether the gash on the underside of the Shuttle's belly needs to be filled with goo.

Posted by Josh Reiter at August 17, 2007 07:14 AM

What pray tell was the two and a half year delay after the Columbia accident for? Why bother doing the full inspection of the tiles if one is not going to bother repairing damage that goes right down to the aluminum? Does NASA as an institution learn *nothing* from previous tragedies?

Posted by Ed Minchau at August 17, 2007 08:17 AM

Given the apparent ease with which Steve Robinson was positioned under Discovery in order to remove the protruding gap fillers on STS114, I would have thought that someone going under Endeavour to fill that hole with putty would not be such a big deal.

But I assume, and hope, they know what they're doing. And given recent NASA history that may be a big assumption on my part.

Posted by Cecil Trotter at August 17, 2007 08:40 AM

Excepting that I know nothing about the design principles involved w/ the shuttle tiles and how they adhere...and lots of other stuff about how they do this... ;-)

Has anybody considered using a tent (for lack of a better term) to effect a repair of the shuttle tile. As I understand, the primary problem is the tiles are attached on Earth, in an Earth environment, and so forth. So make an attachment that can glom on wherever you need it, pressurize it, make the repair, let it 'cure' or whatever. Is there any sort of 'outside the box' type thinking by the smart guys at NASA or is everything limited to 1 dimensional thinking?

Flame away.....

Posted by CJ at August 17, 2007 10:25 AM

CJ: "As I understand, the primary problem is the
tiles are attached on Earth, in an Earth
environment, and so forth."

Actually the big issue is that repair efforts may
risk making things worse. If the repair ends up
lumpy and creats a shock wave impingement pattern
that makes a hot spot (as the X-15 project found
out by experience, hypersonic air streams can be
nasty that way), or if they put a big scritch in
the tiles trying to fix a smaller one (always a
possibility working in free-fall near the fragile
TPS), they could be really hosed...

-dw

Posted by dave w at August 17, 2007 02:56 PM

Just to clear up a few things...

Why bother doing the full inspection of the tiles if one is not going to bother repairing damage that goes right down to the aluminum?

The inspection found that the damage wasn't right down to the aluminum. Had it been, a repair may have been necessary.

Given the apparent ease with which Steve Robinson was positioned under Discovery in order to remove the protruding gap fillers on STS114, I would have thought that someone going under Endeavour to fill that hole with putty would not be such a big deal.

The repair would require two astronauts to be under the vehicle, and one of them would be on the extension boom, which Steve Robinson didn't need. Also, Steve Robinson need only to grasp the gap filler and pull it out (away from the vehicle). He didn't need to carry a rather large dispensing tool which could damage tile. He also needed the move towards the TPS once.

CJ, I'm not sure what you are saying. If you mean applying the tiles on orbit, then you need to understand the resource requirements. It would take months to apply all the tiles to the bottom of the orbiter with dozens of technicians working 3 shifts.

Posted by Leland at August 17, 2007 03:15 PM

I stand corrected, the gouge is not quite down to the aluminum. There is a thin layer of felt still on the aluminum.

Here is a picture of a 3d model of the gouge:
http://news.scotsman.com/latest.cfm?id=1298302007

Dave W, when I look at that gouge - the size of my thumb - I honestly can't see a repair being lumpier than the existing gouge.

Posted by Ed Minchau at August 17, 2007 04:06 PM

Dipshits.

I guess anyone with a webpage can feel important behind a keyboard.

"Biting Commentary about Infinity, and Beyond!" LOL!

Posted by Nick at August 18, 2007 11:08 AM

"Sorry, Keith, but it wasn't a joke. It's a description of reality. I know that you have trouble with that sometimes."

I am not at all surprised that you don't understand the words you wrote - or the impression they have left on people.

Posted by Keith Cowing at August 18, 2007 03:23 PM

Keith, those people are big boys and girls. They knew the job was dangerous when they took it. Certainly if I were one of "those people," I'd understand the sentiment.

Let me repeat again. We have lots of astronauts, and plenty more where they came from. As I wrote once:

...while this may sound callous, the space program will go on just fine without them. They knew their job was hazardous, they did it anyway, and by all accounts, they died doing what they wanted, and loved, to do. There are many more astronauts in the astronaut corps who, if a Shuttle was sitting on the pad tomorrow, fueled and ready to go, would eagerly strap themselves in and go, even with the inquiry still going on, because they know that it's flown over a hundred times without burning up on entry, and they still like the odds. And if yesterday's events made them suddenly timorous, there is a line of a hundred people eagerly waiting to replace each one that would quit, each more than competent and adequate to the task. America, and the idea of America, is an unending cornucopia of astronaut material.

But we only have three orbiters left. That is the critical and finite resource.

Posted by Rand Simberg at August 18, 2007 03:48 PM

Rand, you obviously don't get it. You must be great company at parties.....

Posted by Keith Cowing at August 18, 2007 04:20 PM

Well, Keith, maybe people were just being polite, but I've never gotten any complaints. And that includes parties with astronauts.

Maybe most people just aren't as quick to get their panties in a twist as you are. Have you noticed that no one else seems to think that my comments are as reprehensible as you seem to?

Posted by Rand Simberg at August 18, 2007 05:32 PM

The people who have commented to me don't visit your site- normally. This post of yours is the reason why they won't be back.

Have fun discussing this with your little pals on USENET ...

Posted by Keith Cowing at August 18, 2007 07:13 PM

The people who have commented to me don't visit your site- normally.

Ah, the lurkers support you in email, but they can't be bothered to comment themselves.

(To the tune of "My Bonny lies over the ocean")

The Lurkers support me in email
They all think I'm great don't you know.
You posters just don't understand me
But soon you will reap what you sow.

Lurkers, lurkers, lurkers support me, you'll see, you'll see
Off in e-mail the lurkers support me, you'll see.

The lurkers support me in email
"So why don't they post?" you all cry
They're scared of your hostile intentions
They just can't be as brave as I.

One day I'll round up all my lurkers
We'll all have a blog of our own
Without all this flak from you morons
My lurkers will post round my throne.

This post of yours is the reason why they won't be back.

Boo Hoo.

If so, their loss, not mine.

Posted by Rand Simberg at August 18, 2007 07:44 PM

KC: "The people who have commented to me..."

I guess we have to take your word on that since you don't allow public posting on your blog as does Rand. I wonder why that is?

Posted by Cecil Trotter at August 19, 2007 06:20 AM

"I guess we have to take your word on that since you don't allow public posting on your blog as does Rand. I wonder why that is?"

You can always start your own website, Cecil. No one is forcing you to read NASA Watch ;-)

Posted by Keith Cowing at August 19, 2007 08:34 AM

Just like no one is forcing you to come here and getting all upset by posts on Rands site. ;-)

Posted by Cecil Trotter at August 19, 2007 02:48 PM

I have stated many times on my blog that the shuttle is a terrible design, a flying kludge, and that the law of averages is working against NASA and that they will almost certainly lose another one before the fleet is scheduled to retire. And yet, if the opportunity was offered to me to strap myself into that flying deathtrap tomorrow, I'd jump at the chance. I doubt that I am alone in that sentiment.

Astronauts are relatively cheap to produce - it is a few million, tops, to have a kid, raise him, educate him, and then provide the further training necessary to become an astronaut. An orbiter, however, costs two billion dollars give or take.

Quick! Without looking it up, name the seven astronauts who died in Challenger, or the seven who died in Columbia. Can you? And this is a community of space geeks. Do you think that a random member of the general poplation could do the same, or could name the three astronauts who died on Apollo 1? What Rand said may seem cold or callous, but he's absolutely right. People are expendable, to everyone but their family and closest friends.

Posted by Ed Minchau at August 19, 2007 05:16 PM

"People are expendable, to everyone but their family and closest friends."

Typical space geek - callous over-simplification - devoid of human emotion or compassion ....

Posted by Keith Cowing at August 19, 2007 05:54 PM

Typical Keith Cowing, self righteous and full of himself.

Posted by Cecil Trotter at August 19, 2007 07:01 PM

Yes Keith, it is callous. No doubt about it. However from what I can tell the universe isn't compassionate - I've lost track of the number of times I have heard the phrase "life isn't fair". Many of the times I have heard the phrase uttered, it was said by my own mother, who is a nurse and one of the most compassionate people I have ever met.

I do feel sorry for those who have lost loved ones in space, just as I feel sorry for the families of those trapped miners. However, no amount of compassion changes the calculus.

There are hundreds of qualified astronauts who would fight each other if they had to for the chance to go up on the next shuttle mission even if this one ends in tragedy. However, if this mission does end up with loss of crew and vehicle, it will not be the loss of the crew that prompts a big investigation and a halt to launches - it will be the loss of the orbiter that does.

Posted by Ed Minchau at August 19, 2007 08:41 PM

"However, if this mission does end up with loss of crew and vehicle, it will not be the loss of the crew that prompts a big investigation and a halt to launches - it will be the loss of the orbiter that does."

I guess you were not watching television after the Challenger and Columbia crew losses.

No one held church services for lost orbiters. Nor is either orbiter's debris buried at Arlington.

Posted by Keith Cowing at August 19, 2007 10:16 PM

Yes I did Keith, and it was very sad. I can also remember exactly where I was and what I was doing when Challenger blew up; it was one of the defining moments of high school for me. But I also remember the aftermath, and how once the astronauts were memorialized that the attention of NASA focused on the loss of the vehicle. It isn't referred to as the Resnick/Scobee/Onizuka/etc. disaster, it is called the Challenger disaster. When we were watching that giant Y in the sky, we were watching Challenger, not the individuals who died.

There is a time and place for mourning the loss of astronauts, but once that is done there are still lots more astronauts willing to take their place. And yet there are only three orbiters, and if that number drops to two then there won't be any more shuttle missions - but there would still be lots of astronauts milling about at NASA.

I guess what I am saying is that even though what Rand (and I) said might have been harsh, cold, uncomfortable, callous, and so on, that doesn't make it false.

Posted by Ed Minchau at August 20, 2007 08:41 AM

Dave,

Thanks...that does make sense. Then again, it shouldn't be an insurmountable problem.

Leland,

I wasn't suggesting ALL of the tiles. If that were needed then scuttle the shuttle. I figured (in this case) only two tiles would need a repair...so do just that. Dave pointed out an obvious problem to that idea but it should be correctable. I guess there's more to attaching a tile than applying some glue and tamping it down. It just seems to me the Shuttle engineering (which is impressive from my point of view) was, and is, an all or nothing approach. That could indicate an 'in-a-rut' philosophy w/ respect to problem solving...which is where the out of the box thinking becomes quite valuable (at times).

Posted by CJ at August 20, 2007 09:43 AM

Nor is either orbiter's debris buried at Arlington.

Rand, is that really Keith's IP address posting these assine comments? I would think that the editor/founder of NASA watch, would know where the orbiter debris is stored and why it is stored there. Only a moron would suggest burying a machine in a cemetary, but it's not like Challenger or Columbia were sold for scrap or placed in junkyards like other wrecks. I can assure anyone that the collected debris and storage is well documented and better known than the final resting places of Grissom, Chafee, White, Scobee, Smith, Resnik, Onizuka, McNair, Jarvis, McAuliffe, Husband, McCool, Brown, Chawla, Anderson, Clark, Ramon, and Carter.

I think the whole side discussion "Keith Cowing" started is from the mind of a troll, who apparently is so bored that he has to write inflamatory material, and then check back to see if he got a rise. Whoever that person is, life must really suck for them, if they have a life at all.

Posted by Leland at August 20, 2007 11:10 AM

CJ,

The original repair concept was quite similar to your line of thought. The problem is that the RTV (glue) doesn't cure in that environment, so what glue do you use? Also, the glue has some pretty good thermal properties of its own but compared to the tile, it is very heavy for use across the entire vehicle. Therefore, it was decided to just fill in the damaged area. A slightly different material was selected for the environment, but it has its own problems.

I apologize if I seemed patronizing, as I was very tired when I wrote the other response. I really didn't understand the question but wanted to help explain the situation.

Posted by Leland at August 20, 2007 11:20 AM

CJ,

Also, you repair sounds a little like the GFE tile overlay repair option. It was considered for this repair and rejected. There was a lot of debate, but I think a fair difference is that the overlay was for much larger damage and a more critical circumstance. Many of the EVA concerns were the same. Still, the repairs options were essentially moot points in regards to whether a repair was needed (or simply put, the repair risks didn't play into the analysis of the damage itself).

Posted by Leland at August 20, 2007 12:29 PM

Leland, whether that was Keith Cowing or not (and I have no reason to suspect that it isn't), he does raise points that needed to be addressed.

Posted by Ed Minchau at August 20, 2007 12:37 PM

"I think the whole side discussion "Keith Cowing" started is from the mind of a troll, who apparently is so bored that he has to write inflamatory material, and then check back to see if he got a rise. Whoever that person is, life must really suck for them, if they have a life at all."

Yes. Life really does suck for me. I am sooo bored these days. Oh wait - looks like CNN is calling again ...

Posted by Keith Cowing at August 20, 2007 02:06 PM

Thanks Leland...I guess it would be easier to fix things up if Starbase 47 were available!

;-)

Posted by CJ at August 20, 2007 02:31 PM

So, Keith, you're not going to explain your strange comment about a "link to a drunk astronaut story"? What was that all about?

Posted by Rand Simberg at August 20, 2007 02:42 PM

My error - you made certain to point to a story about a *crazy* astronaut not a *drunk* one. Same difference - you just can't pass on the chance to point to such things - as if astronauts are somehow less valuable than a piece of hardware since there are so many of them - some of whom have problems.

Posted by Keith Cowing at August 20, 2007 03:03 PM

My error - you made certain to point to a story about a *crazy* astronaut not a *drunk* one. Same difference - you just can't pass on the chance to point to such things - as if astronauts are somehow less valuable than a piece of hardware since there are so many of them - some of whom have problems.

In other words, despite the slight correction, you completely missed the point of the story at the link, which was about the NASA culture (including George Abbey), and why they have too many astronauts.

Of course humans are important, but (unlike scarce and expensive, and hard to replace pieces of hardware) they're not billions of dollars important. Opening up space is what's important, and people die opening frontiers. This is as it's always been.

NASA's (and the nation's, which abets it) astronaut culture is a hindrance, not an aid, to that endeavor.

Posted by Rand Simberg at August 20, 2007 03:22 PM

You don't get it - nor will you. Have a nice day.

Posted by Keith Cowing at August 20, 2007 03:23 PM

Typical space geek

This from a guy who paints Vulcan ears on astronauts.

Posted by T.L. James at August 20, 2007 04:16 PM

"This from a guy who paints Vulcan ears on astronauts."

Gee, I never said I wasn't a space geek.

Funny how the astronauts always request hi-res copies of these images for their "files" ....

Posted by Keith Cowing at August 20, 2007 04:38 PM

You don't get it - nor will you.

Apparently not. I don't consider that a problem.

Still waiting for someone to support your position.

[sound="crickets chirping"]...

[/sound]

Posted by Rand Simberg at August 20, 2007 06:12 PM

OK, so Rand doesn't get it, and neither do I. What is it about our cold, callous position that is incorrect? Because if it is correct that astronauts are far more expendable and replaceable than the vehicles that they ride, then no amount of compassion will change that. What am I missing, Keith?

Posted by Ed Minchau at August 21, 2007 01:04 AM

OK, so Rand doesn't get it, and neither do I. What is it about our cold, callous position that is incorrect?

You insist on using cold, hard rational thought, when you have to use Emotion! Feeling! Empathy!

How terrible and western and non-PC of you.

The cold fact is that if an activity is really worthwhile, we as a society easily tolerate deaths in its pursuit. Be it transportation, construction, public safety, mining, farming, and so on, we in the US tolerate thousands of deaths per year as the cost of doing business. These deaths are avoided when it it practical (read: economical) to do so. Economists put the value of a human life (as revealed by the actions of individuals when they trade their own safety against costs and benefits to themselves) at somewhere around $7 million.

When there's a big fuss about astronaut deaths, it's not because astronauts are so much more valuable than this. It's because the suckers in the cult of astronaut worship will feel bad if astronauts die. I do not think that salving Mr. Cowing's feelings is an adequate reason to spend excessive amounts on astronaut safety.

Posted by Paul Dietz at August 21, 2007 06:55 AM

Keith,

You are absolutely right. It was a cold, calculated statement of the astronaut culture, and in itself was pretty much nil in the compassion department. What you are missing is that none of us who understand the reality of things is unfeeling or unconcerned for their welfare. Or their families.

It is merely a matter of stating of the facts, suspending it from the emotion of the potential loss that the facts present.

As for compassion for fallen astronauts, I think Rand understands and you do not, that frontiers are often paved with graves of the intrepid. No DECENT person can disparage that, and neither should they deny it.

If we didn't possess the ability to divorce our fear of loss from the technical and interpersonal realities of spaceflight, we'll just creep along and continue the wailing and gnashing of teeth when an astronaut dies. THAT would be insulting those who have already paved the way.

Posted by J. Craig Beasley at August 21, 2007 07:00 AM

"As for compassion for fallen astronauts, I think Rand understands and you do not, that frontiers are often paved with graves of the intrepid. No DECENT person can disparage that, and neither should they deny it."

Nah, I don't understand the concept at all.

I am co-chairing this event: http://www.riskexplore2007.com/

and came up with the idea for -and co-edited the proceedings of this one: http://www.riskexplore2007.com/risk_and_exploration_1_2004/

And was just elected a Fellow of the Explorers Club. Nah this concept you mention is just alien to me - NOT.

Do some research the next time.

Posted by Keith Cowing at August 21, 2007 09:03 AM

Keith,

You must be deliberately obtuse, gotta be trying hard to NOT understand what people are saying, so I will sum up:

Astronauts are people we care about, and we try very hard to keep them flying safely. In some cases, safety is a relative thing. The crews understand that condition.

Rand pointed out that the ratio of astronauts-to-spacecraft at NASA is a high number. This is another condition that the astronauts understand.

The astronauts understand these conditions and accept them generally in the same cold way, when the day is done. You suggest that Rand highlighting this information is somehow an uncompassionate thing to do.

You are going ballistic over the information more than the ones doing the flying.

I said that "frontiers are often paved with graves of the intrepid", and to further clarify, this is an ground rule for being an astronaut, and it would uncompassionate not to acknowledge such. THAT is what you don't seem to understand.

Posted by J. Craig Beasley at August 21, 2007 09:55 AM

Rand pointed out that the ratio of astronauts-to-spacecraft at NASA is a high number. This is another condition that the astronauts understand.

The astronauts understand these conditions and accept them generally in the same cold way, when the day is done. You suggest that Rand highlighting this information is somehow an uncompassionate thing to do.

You know this just isn't the sort of things that astronauts have ever said to me ... I guess I am - and they are - obtuse as well.

Posted by Keith Cowing at August 21, 2007 10:33 AM

All I can do is shrug. I am sure you have met more astronauts than I have in your line of work, but those I talk to on an infrequent basis have related that they know the risks are there. They accept it as a environmental necessity, and without much fanfare. Of course, risk mitigation is always a popular idea. :)

Keith, you do good work. I'll never fault you for keeping NASA honest, somebody has to perform that duty. However, on this issue, I respectfully disagree with you.

Posted by J. Craig Beasley at August 21, 2007 11:40 AM

I'm curious how many people are impressed by:

looks like CNN is calling again ...

You don't get it - nor will you.

And was just elected a Fellow of the Explorers Club. Nah this concept you mention is just alien to me - NOT.

You know this just isn't the sort of things that astronauts have ever said to me

This is what I take from these comments:
* He has a very high opinion of himself
* Thinks others are incapable of understanding his level of thinking
* We simply don't have his credentials
* We're not part of his "in" crowd.

I'm not impressed with his logic. I am happy he's not making decisions for NASA, because we don't need feel good ideas that others won't understand. I may have participated in a cold calculated decision, but if I was unable to explain the reasoning to others, than instead of worry about a risk of loss of vehicle during entry, we might have risked a crew member doing an unnecessary EVA.

Posted by Leland at August 21, 2007 12:21 PM

You are so right Leland. I am such a schmuck. Bad Keith. BAAAD Keith.

Posted by Keith Cowing at August 21, 2007 01:27 PM

You know what guys, this doesn't need to become a personal mudslinging match; obviously such is getting us nowhere. Let's try to keep focus on the issue: that NASA knew it had tile damage, but decided against repairing it, thus showing that they learned absolutely nothing from Columbia. Rand (and I) are more concerned about what could have been the possible loss of vehicle than we were about the possible loss of crew. Keith is apparently more concerned about what could have been the possible loss of crew, and took umbrage at the suggestion that astronauts are expendable when compared to the vehicle.

Having hopeflly yanked the conversation away from the ad hominems, I would still like for Keith to explain why what I said is incorrect.

Posted by Ed Minchau at August 21, 2007 05:42 PM

this doesn't need to become a personal mudslinging match

Let's try to keep focus on the issue: that NASA knew it had tile damage, but decided against repairing it, thus showing that they learned absolutely nothing from Columbia.

The decision to not repair was based first on imagery. Imagery that was not available for Columbia. The imagery was used to make engineering judgement on the scope of damage, which was done pre-Columbia with only review of ascent video. Then the size estimates were run through a series of thermal math models, some pre-Columbia but most post Columbia and enhanced after lessons learned during return to flight. The results of the math models were correlated with various tests in lab facilities that didn't exist pre-Columbia. AFter reviewing the data, a conclusion was made that a repair wasn't necessary on orbit. Maybe you missed the landing today.

Say again about not mudslinging and how nothing was learned.

Posted by Leland at August 21, 2007 05:50 PM

Touche.

Posted by Ed Minchau at August 21, 2007 08:28 PM

"The decision to not repair was based first on imagery. Imagery that was not available for Columbia. The imagery was used to make engineering judgement on the scope of damage, which was done pre-Columbia with only review of ascent video. Then the size estimates were run through a series of thermal math models, some pre-Columbia but most post Columbia and enhanced after lessons learned during return to flight. The results of the math models were correlated with various tests in lab facilities that didn't exist pre-Columbia. AFter reviewing the data, a conclusion was made that a repair wasn't necessary on orbit. Maybe you missed the landing today."

Additionally, the math models were backed up by actual plasma-jet tests where full-scale replicas of the damaged area were subjected to reentry forces. Also, similar scale models of the gouge were put through repair operation tests with the patch kit. This episode was not evaluated by computer simulation alone.

The risk of damage to the orbiter, let alone loss of it and the crew, was much lower than the now pedestrian risks of an EVA to patch the gouge. Also, who is to say the patch may not have given way and yanked out more tile on reentry?

Yes, we learned a lot from Columbia, and we think and test before blindly acting.

Posted by J. Craig Beasley at August 22, 2007 12:33 AM

Touche.

It's ok Ed, because if you hadn't used the word "nothing", then my rebuttal would have been a bit harder to write. After two missions in a row, we still not sure about the repair techniques themselves, and that's not good. Considering the larger picture, NASA has the lead role (and should at this point) in determining methods to extending space activity beyond orbit, and that will require conducting repairs in orbit. Repairs not just on the space station, but on the orbiter itself. In that realm, there is some room to learn a lot more.

Posted by Leland at August 22, 2007 09:07 AM


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