August 13, 2007

I have a bad feeling about this

Saith the AP:

NASA discovered a worrisome gouge on Endeavour's belly soon after the shuttle docked with the international space station Friday, possibly caused by ice that broke off the fuel tank a minute after liftoff.

The gouge — about 3 inches square — was spotted in zoom-in photography taken by the space station crew shortly before Endeavour delivered teacher-astronaut Barbara Morgan and her six crewmates to the orbiting outpost.

Saith Wired:

The gouge is located about 1.2 meters away from Endeavour's right landing gear door, and measures 9 cm by 5 cm long. This takes it across two of the shuttle's tiles. NASA believes that a chunk of foam dislodged from the fuel tank, fell down, carved out this hole, and left some secondary damage further down the shuttle.

What's worrying is that during this initial strike, the hole goes all the way down to the shuttle's undercarriage, exposing some of the felt filler material underneath. Without any preventative measures, this could become a weak point for hot plasma during the shuttle's reentry through the Earth's atmosphere.

I've got a very bad feeling about this. Here's hoping fervently that my misgivings are wrong.

Posted by: Steven Den Beste in System at 10:44 PM | Comments (27) | Add Comment
Post contains 201 words, total size 2 kb.

1 Time to test the new patching materiel they're supposed to be carrying...

Posted by: Cybrludite at August 13, 2007 11:47 PM (XFoEH)

2 That's risky, too. People on the ground are working right now to try to make the decision as to which is the lesser risk.

Posted by: Steven Den Beste at August 13, 2007 11:50 PM (+rSRq)

3 If it's a question of risking two astronauts on the space walk vs. risking the whole shebang on re-entry, then I'd go with the space walk. Or is the risk that the patching materiel itself would cause problems on re-entry?

Posted by: Cybrludite at August 14, 2007 03:48 AM (XFoEH)

4

The scary thing is that this icing problem is happening in high summer.  Why did it suddenly become a problem in the last few years?  Because the foam insulation was reformulated due to "environmental concerns."   These shuttles cost something like $1.2B (replacement cost) each in today's currency, and are our only manned space launcher right now. 

I could go on a while, but the message should be clear:

1. We are wasting billions and lives for a questionable,  unquantifiable, but tiny environmental benefit (foam on tanks for ~8-12 launches per year).

2. The environmental movement is killing our space program. And astronauts.  We can only hope at this point that they haven't just killed some more.

I'm disgusted that NASA would let this go on.  They've got no business destroying our space program and national prestige with such abysmal management principles.

Posted by: ubu at August 14, 2007 06:05 AM (dhRpo)

5 To the best of my knowledge, the foam reformulation has absolutely nothing to do with the foam loss. It always was an issue and nobody paid attention before Columbia. STS-27 landed with worse damage.

And anyway, read this:
http://www.spaceflightnow.com/shuttle/sts118/070813mmt/

I surprised that AP and Wired pretty much got the story straight (at least in the quotations Steven used). The filler material is between the tiles and not underneath, but it's a minor mistake.

Posted by: Pete Zaitcev at August 14, 2007 08:30 AM (9imyF)

6

If you notice in the picture, every one of the tiles has a unique serial number. That's because every tile is different. They're all machined for the positions they must fill.

To do a repair, the astronaut has to dig out the existing tile and then glue in another one. But the other one won't be precisely right, and maybe the glue won't hold during reentry.

The risk of using the patching kit isn't from the space walk, the risk is losing the ship during reentry when a gap around the patched tile leads to a burn-through, or when the patched tile comes loose and is pulled off.

Posted by: Steven Den Beste at August 14, 2007 08:30 AM (+rSRq)

7

I can't imagine what is going through the minds of the astronauts right now. Do we risk floating off in to space to glue a new tile in to place, or do we say screw it and hope it holds? Not a terribly extensive list of options.

This leads me to wonder why don't they have an escape capsule of some sort on the ISS? Don't these guys watch sci-fi at all? Everyone has escape capsules.

The other possibility I suppose would be to junk the shuttle and have a Soyuz capsule come and take them home, although I wonder how long the ISS could handle that many visitors.

 

 

Posted by: Tman at August 14, 2007 10:06 AM (Gt906)

8 Actual repair techniques available were listed at the link I posted. In short, replacing a tile in space is not possible. Instead, three options are available:
1. Paint the hole's inside with a black paint. This improves the heat removal by radiation
2. Fill the hole with a caulk (and then paint it)
3. Apply a patch, secured with screws into tiles.
As far as I know, tiles are not gouged further for option #3, so the patch is not flush with the surface.

Posted by: Pete Zaitcev at August 14, 2007 11:15 AM (9imyF)

9

The Shuttle can land itself without pilots. One scenario is that the entire crew does stay on the ISS and get evacuated with Soyuz capsules, and the Shuttle gets sent back without a crew.

But I doubt they'll do that.

Posted by: Steven Den Beste at August 14, 2007 02:19 PM (+rSRq)

10

I have to wonder how bad the odds would be before NASA would go with the pilot-less shuttle landing/Soyuz rescue scenario you describe.

Then I imagine being an astronaut on this mission waiting for a large faceless bureaucracy to decide how much I'm worth to them. That's a pleasant thought.

Posted by: Tman at August 14, 2007 03:05 PM (Gt906)

11

Or is the risk that the patching materiel itself would cause problems on re-entry?

I think the risk is that they just don't KNOW what will happen, since it's never been tried before.  They might have this dangerous space walk go absolutely right, the astronauts' work be 100% perfect, and it might STILL fail during re-entry, because of who-knows-why. 

Which is probably what they said when a shipwright first designed a sail-powered vessel.

The difference being, of course, that they don't HAVE to risk the crew; there could be a rescue mission, or the current crew could re-enter via repeated... um... Soyuz(?) capsules from the ISS.

I'm pretty sure I wouldn't want to make the call.  I DO know I wouldn't ever say "Let the shuttle come home alone."  That would kill NASA dead.

Posted by: Wonderduck at August 14, 2007 05:40 PM (fEnUg)

12 Didn't I hear something about them working up a simulation in one of their windtunnels? They are trying to duplicate the tile damage as best as possible then check to see how it behaves with and without the patch when subjected to hypersonic plasma.

Posted by: Will at August 14, 2007 05:48 PM (olS40)

13

Will, there's no possible way to do this in a wind tunnel. During reentry, the shuttle is moving at 25 times the speed of sound.

Computer simulation would be the only hope, and even that would be problematic. I suspect we don't really understand fluid dynamics at those speeds well enough to really write a decent simulation. And it isn't helped by the fact that near the nose and underside of the shuttle, the air is being turned into a plasma by the heat.

Posted by: Steven Den Beste at August 14, 2007 07:13 PM (+rSRq)

14

It may have been some know-nothing on the radio. It did sound fishy at the time. A couple guys hacking on putty with a plasma cutter would probably look like a simulation to a lot of people.

It's a shame we didn't get more than a basic introduction to hypersonic flow in my gas dynamics classes, but once the molecules start breaking down, everything goes to hell in a handbasket (aka non-linear). They're not going to drop undergrads in that swamp.

Almost all the hypersonic design happening today is done with CFD, and from what I understand, they actually have a pretty firm grasp on what's going on.

Posted by: Will at August 14, 2007 08:40 PM (olS40)

15

On a tangental note, every F1 team has a CFD group in house, and a few of the Chief Designers are CFD specialists.  Only one team doesn't have a windtunnel of their own (Spyker, and they're about to purchase the old Team Jaguar factory, which DOES have a 'tunnel), a couple have two.

I'd think that they probably DO have good models for the Shuttle and how it should react during re-entry ("Step 3: A Miracle Occurs").  The problem that I see, however, is that they just don't have actual experience with the patch stuff, how it deals with re-entry and the like.

Which is good and bad, of course.  Good, because they've never had to use it, bad because they don't know how it'll react.

Until they DO use it, they won't KNOW...

Posted by: Wonderduck at August 14, 2007 09:11 PM (fEnUg)

16 The Wikipedia article for CFD shows a simulation of the shuttle, but I doubt they're modeling it down to the level of individual tiles, or are capable of figuring out the consequences of slight irregularities at the level of individual tiles.

Posted by: Steven Den Beste at August 14, 2007 09:42 PM (+rSRq)

17
Will, there's no possible way to do this in a wind tunnel. During reentry, the shuttle is moving at 25 times the speed of sound.
NASA do have supersonic wind tunnels, but I don't think they have anything nearly that fast. A quick bit of Googling turned up one that can reach Mach 7, which is still pretty amazing.

Hope they find a solution and that it works.

Posted by: Pixy Misa at August 14, 2007 11:42 PM (PiXy!)

18

Hmm... Wait a second...Texas A&M... Let me just see...

Ah, there he is. That's who taught my gas dynamics class. He took the Unsteady Wind Tunnel with him to Texas when he left ASU.

Posted by: Will at August 15, 2007 08:57 AM (SOx9v)

19 Good, because they've never had to use it, bad because they don't know how it'll react.

One submits that they did need it once...

I'm not certain why this would be a "dangerous" spacewalk. It's their own vehicle they're working on, so there's no real difficulty in interception. Perhaps it's just the time involved?

Also, just saw CNN run pictures of a NASA test bed... evidently they mocked up the tile setup, replicated the gouge, and used an arc-jet furnace to simulate the plasma at re-entry. Melted a bigger gouge down the tile, but didn't go deep. 'cos, whether that's what would actually happen...

Posted by: Avatar_exADV at August 15, 2007 10:20 AM (LMDdY)

20

I believe the current rescue plan calls for NASA to outfit another shuttle ASAP and send it up within 1 month, and returning with both crews.

 

Posted by: RickC at August 15, 2007 03:01 PM (PoCOp)

21

One submits that they did need it once...

Did they have it then?  Did they even KNOW they needed it then?

Posted by: Wonderduck at August 15, 2007 04:14 PM (fEnUg)

22 The bottom line:  we need a replacement for the outdated POS known as the shuttle.

Posted by: metaphysician at August 15, 2007 05:21 PM (hnYuE)

23 More or less my point, Duck. (No, they didn't have it then.)

Posted by: Avatar_exADV at August 15, 2007 07:13 PM (LMDdY)

24 The simulation facility is mentioned on the link that I posted. (Obviously, nobody reads reputable websites anymore. No, I'm not bitter.) Basically, it involves blowing compressed air from a tank over an arc furnace which creates a hypersonic flow of plasma.

I used to live near a facility which had an experimental H/F laser, for the Soviet reply to the SOI. An H/F laser is powerful enough to melt satellites in orbit, so the idea was to melt Reagan's toys without launching anything, because launchers can be intercepted by the same SOI kit. Anyway, it works by blasting hydrogen and fluoride through and across an orifice. The hypersonic shockwaves were heard all over the town whenever they fired it up.

I wonder if neighbours of the tile heating and simulation facility are filing noise abatement lawsuits. Those NIMBY people are everywhere

Posted by: Pete Zaitcev at August 15, 2007 07:16 PM (9imyF)

25 The spacewalk is dangerous because it's easy to make a wrong move with the boom and make another hole in the heat shield, which may end located not quite as fortunately over a stringer as the existing one. Haven't you seen Rocket Girls? Remember how someone moved the arm backwards? Ha, ha, only serious. It's not likely that the operator would do the same mistake, but the real danger is in the unpredictable flex of the extension boom.

Posted by: Pete Zaitcev at August 15, 2007 07:20 PM (9imyF)

26 I believe the current rescue plan calls for NASA to outfit another shuttle ASAP and send it up within 1 month, and returning with both crews.

Send up another shuttle within 1 month? Does NASA have the required magic pixie dust to make that happen? Or do they have another shuttle on hand that doesn't require 20,000 engineers and technicians to service it?

Pardon my skepticism. But although "fast turnaround" was one of the selling points of the shuttle program, NASA has never actually managed to do it. They can't; the system is incapable of it.

Considering that NASA, after Apollo, became a jobs program for aerospace engineers, it's not really all that surprising. If Endeavor cannot be patched in orbit, if there is no way to safely get the crew home, those people will either be stuck at the USS Boondoggle ISS until NASA actually can ready another shuttle, or have to come home on Soyuz capsules.

Posted by: atomic_fungus at August 16, 2007 11:09 AM (7YxzV)

27

I'm not sure that long-term stay at the ISS is possible. The life support system is designed for three people. How long can it support ten?

I believe that it can probably do so for a couple of weeks, and maybe even a month. But how long can it produce breathable air? How long before the food runs out? The supply capsules (Soyuz) are scheduled years ahead; the Russians are no more able to advance their schedule than we are. Maybe less, in fact.

And I'm not sure that supply capsules can be used to evacuate crew.

The ISS has a single Soyuz capsule connected to it at all times. It's the emergency escape for the three normal crew. But evacuating ten is more of a problem.

The reality is that if they can't fix the problem, then they're going to have to risk reentry anyway. There is no alternative.

And if they lose a third orbiter, then that should be the end of the program. Absolutely no more launches, zero, nada. (Myself, I think they should have ended it after Columbia.)

Posted by: Steven Den Beste at August 16, 2007 03:15 PM (+rSRq)

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