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Shuttle Launch Pad Damaged During Discovery's Launch
Posted by
ScuttleMonkey
on Mon Jun 02, 2008 01:52 PM
from the time-to-upgrade dept.
from the time-to-upgrade dept.
pumpkinpuss writes "Launch pad 39A at the Kennedy Space Center suffered unusual damage during the shuttle Discovery's blastoff Saturday. Pictures from a NASA source show buckled concrete and numerous concrete blocks or bricks, presumably from the flame trench, littering a road behind the pad."
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anyone know? (Score:4, Insightful)
Re:anyone know? (Score:5, Funny)
Parent
Re:anyone know? (Score:5, Insightful)
Parent
Re: (Score:3, Informative)
Re:anyone know? (Score:4, Insightful)
2. Make a post explaining that it was a joke
3. Get mod'ed as Informative
4. Get Karma
5. ???
6. Profit!
Parent
Re:anyone know? (Score:4, Informative)
Parent
Re:anyone know? (Score:5, Informative)
39B has already started to be refurbished for Project Constellation, launching the Ares Saturn like rockets. The plan is that 39A will follow suit after the last of the space shuttle missions are finished.
Parent
Re:anyone know? (Score:5, Informative)
Parent
Re:anyone know? (Score:5, Informative)
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Re:anyone know? (Score:4, Funny)
Parent
So, in other words... (Score:5, Funny)
Kinda old (Score:4, Informative)
http://en.wikipedia.org/wiki/Kennedy_Space_Center_Launch_Complex_39 [wikipedia.org]
Obvious explanation for the bricks (Score:5, Funny)
In Other News (Score:5, Funny)
Thermal Cycling (Score:5, Informative)
I don't know what these bricks are made of (CNN says they are special bricks but TFA says they are concrete), but I bet water was trapped in between the cracks and crevices of these bricks and then suddenly boiled when it was heated by rocket exhaust. The steam rapidly escapes from the bricks and makes the cracks a little bigger. This occurs over and over again, each time the cracks get a little bigger. Finally, the cracks become big enough that the bricks can't stand the stress anymore. They get heated one more time and explode. It only takes one brick to explode to cause a chain reaction, and wipe out a bunch of them.
This is of course, the simplest explanation. I would hope NASA would have thought of this before. It happens all of the time with the freeze and thaw cycles in highways and bridges. However, sometimes the simplest explanation is the best.
Re: (Score:3, Informative)
i am sure it falls under both groups "concrete" and "special bricks"
and your right in that it more than likly is a water issue.. the trick is deterimingin where - how much - and is the section that failed the only one.
Re:Thermal Cycling (Score:4, Funny)
Parent
Modern concrete is advanced stuff (Score:5, Interesting)
My friends own a commercial concrete contractor, and current concretes are WAY more advanced than I'd ever have thought.
These days, concrete is like any other advanced man-made composite. The knowledge about cement, water, sand and aggregate types and mixes have been refined to the nth-degree. Then start add-mixing plasticizers, hardners, cure retarders / accelerators, humidity control agents, etc.
The really advanced stuff is like epoxy. Normal concrete is ~3,000psi. My friend was pouring 12,000+ psi concrete for a large structural member in a sub-foundation. The form blew out, and concrete flowed out the hole and setup - within a few hours, even jackhammers became ineffective - it was like drilling steel. They wound up bringing in heavy demo equipment to get out what should have only taken a few men.
Parent
Re: (Score:3, Funny)
Re:Thermal Cycling (Score:5, Interesting)
Each batch is specifically formulated to be as identical to the ones before it as possible. While there might me MINOR variances in mix, most of our modern construction absolutely depends on the homogeneousness of the concrete batches. If we really had to deal with widely disparate batches, ntohing large could ever be built, as the overall strength of the finished product could not be counted on. Yes, there are exceptions to this, some of which have caused rather spectacular engineering catastrophes. But the reason they are a big deal is precisely because they are so rare.
Now, if we were still mixing concrete by hand using slave labor like the Romans, then wide variations in concrete batches would be an issue. But we don't. We use complicated mathematics, and specialized weighing and measuring and mixing machines, all tied together by tried and tested computers and software platforms. Concrete hasn't been an issue of "every mixed batch of concrete is different from the last" for at least 50 years, if not longer.
Also, the types of concrete mixed for high-temperature use such as this WOULD be very different than the types mixed for use in bridges.
Concrete used to be my family's business back in the 50's - 70's. I grew up on stories about the concrete business. Not that I would even need that history to understand this though. Don't any of you ever watch the Discovery Channel? Geez.
Parent
Re:Thermal Cycling (Score:5, Informative)
But go on believing that every batch is identical, the testers on the ground will tell you otherwise. Hell, if what you said was true we wouldn't need testers, the very existence of testings refutes your assertion that there are only minor differences. I've also got a newsflash for you, concrete is a highly forgiving material, even with wide disparity in the mix the design of mixes is done with minimum characteristics in mind. Even today 4000psi concrete is the design norm with 98% of all breaks exceeding that number, most by a very large margin. Recent tests of sac-crete (small, poor aggregates) on a project I worked on yielded 6500psi, far in excess of the minimum strength required of 3500psi. You obviously know nothing about the design and use of concrete in the construction industry. Because concrete is so different per lot random statistical sampling is done to ensure the concrete falls within specific minimum parameters. But keep on believing that fancy computer at the batch plant does anything more than speed up the delivery and mixing rather than ensure consistent batching which has and will always be a human task. A simple pound of rock with 15% more sulfer than the rest can change the mix significantly and 0.5% more moisture in the sand can alter the cement/water mixture significantly.
Parent
Re: (Score:3, Insightful)
Especially since making concrete effectively weather proof hasn't been all that hard for a very long time. You can still go to Italy and find concrete from the Roman times.
Re: (Score:3, Funny)
Re: (Score:3, Funny)
Not too surprising (Score:5, Insightful)
toilet (Score:5, Funny)
"No problem sir!" (Score:4, Funny)
Re:"No problem sir!" (Score:4, Funny)
Parent
Flame tunnel materials (Score:3, Informative)
Since I haven't seen this mentioned elsewhere, this NASA article [nasa.gov] talks about the refactory materials and specifications of the flame tunnel...
Obligatory quote:
Some Hi=Res Closeups of the Aftermath (Score:5, Informative)
The photos show the debris field, holes blown through the security fence by flying debris and the bricks on the walls of the flame trench ripped away. Interesting stuff.
Re:Considering the pounding the pads take (Score:5, Funny)
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Re:Considering the pounding the pads take (Score:4, Informative)
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Re:how? (Score:5, Insightful)
Parent
Re:how? (Score:4, Funny)
Whee!
Parent
Re:how? (Score:5, Informative)
In your glassware example, you heated the piece of glassware slowly, so the thermal gradient was low. In other words the entire piece of glassware was roughly the same temperature while it was heated. When you dropped it into ice water the outside became much colder than the inside because the change in temperature was sudden. I recommend you read this article. [wikipedia.org]
Remember, heat transfer is not instantaneous.
Parent
Re:how? (Score:4, Insightful)
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Re:how? (Score:5, Funny)
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Re: (Score:3, Informative)
Re: (Score:3, Informative)
It knocked everything off the nearby counter top, and we were picking up glass shards for days. My wife was standing pretty close to the stove, but luckily had her back to it. I hate to think of the consequences if she'd turned to face the stove right at that moment. I'm sure
Re: (Score:3, Interesting)
Re:how? (Score:5, Informative)
With nearly 10 million pounds of thrust, I imagine there are still significant blast pressures on that pad even when the shuttle is a kilometer or more above it. For comparison, the blast danger area for other aircraft behind a 747 at full takeoff thrust is more than half a kilometer. If you don't believe that, there's a Top Gear episode that amply demonstrates the fact.
Parent
Also: it's a heavy mission (Score:5, Informative)
STS-124 is carrying Kibo, making it a rather heavy liftoff. It would have taken Discovery a little longer than usual to get away from the pad, subjecting it to a longer duration acoustic/vibration environment.
Also, it wasn't that far off the pad when the bricks were flying off according to this image [aviationweek.com]. (Same photo as TFA, but a little farther out)
Parent
Re: (Score:3, Insightful)
Now, maybe they're carrying less fuel on lighter launches, but I've never heard that before. I can't imagine a 1% variation in liftoff weight making a big difference in time to clear the pad.
Anyone care to contribute some actual time measur
Re:how? (Score:5, Informative)
The 747 would have this same kind os wake evn if all four engines were shut down.
We dont know what happended to the pad yet. my guess is something to do with the combination of heat and old age.
Parent
Re:how? (Score:4, Funny)
Parent
Re:how? (Score:4, Insightful)
That gets my vote too. Anyone who has been there for a launch can tell you that the vibrations from two miles away are incredible. That and Florida is basically a large sand dune.
Parent
Re:how? (Score:5, Informative)
the rockets are causing the damage, so the damage occurs while the rockets are nearby, right?
Well, the rocket exhaust isn't the only high-pressure fluid rushing out through the flame trench in the launch process.
The Sound Suppression Water System [nasa.gov] dumps about 300,000 gallons of water into the launchpad base and exhaust flame ports in the first 20 seconds after engine ignition, so that flow can't be good for the stability of the flame trench insulating blocks as they start to work loose.
Parent
Re:how? (Score:4, Informative)
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Re: (Score:3, Funny)
Re: (Score:3, Insightful)
Today's comment was brought to you by the publishers of "My Very First Big Book of Classical Physics".