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Shuttle Launch Pad Damaged During Discovery's Launch
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."
TFA says the pad is from the Apollo days.
I am a believer of momentum and curves.
It's a joke.
LC39A was used the first time almost 41 years ago by Apollo 4. It was used for more than 80 launches since then. Maybe it's time to replace it?
http://en.wikipedia.org/wiki/Kennedy_Space_Center_Launch_Complex_39
Many. It was built for the Apollo program, first used in 1967 - and handled almost all of the Saturn V Apollo launches bar one (so ~ 16). After that it has, along with 39B been handling Shuttle launches - and so presumably taken close to, if not more than 50% of them (so around 60+). Hence we could be looking at around 70-80 launches - launches of the heaviest kind.
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.
Making things hot and cold in rapid succession can cause fatigue due to the materials expanding and contracting. Things exposed to the elements, such as this, also have to deal with moisture.
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.
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
according to the all-knowing wiki, http://en.wikipedia.org/wiki/Launch_pad_39A/ there have been 82 launches.
It depends on your definition of "nearby".
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.
Random and weird software I've written.
Hmmmm. this will work better.
I prefer the "u" in honour as it seems to be missing these days.
Aside from the astronauts, the closest personnel to a shuttle launch are 1650 meters away. The forward fireman team are in an armored personnel carrier and dressed in reflective fire suits.
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. (Same photo as TFA, but a little farther out)
Kurt Vonnegut: "If you can do a half-assed job of anything, you're a one-eyed man in the kingdom of the blind."
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 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.
Welcome to the Panopticon. Used to be a prison, now it's your home.
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.
Remember, heat transfer is not instantaneous.
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
Put that piece of glassware (say, a pie dish) on your stove burner, and turn the burner on high. That plate will shatter soon enough; I've seen it happen.
The meek may inherit the earth, but the strong shall take the stars.
http://engineer.tamu.edu/news/story/?p_news_id=1220
No, the safety zone that that keep in back of an airliner like the 747 is not due to the engines. It is due to what they call wing tip votices. This is caused by the high presure air rolling around the ends of the wing into the low pressure zon on the top of the wing. The plane leaves a 'wake" that is like two horizonal toranados.
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.
Since I haven't seen this mentioned elsewhere, this NASA article talks about the refactory materials and specifications of the flame tunnel...
Obligatory quote:
This happened with a Pyrex measuring cup and an electric stove. I don't really know the sequence of events that lead to it being on the stove with the element on "high". It didn't seem important enough to notice before the explosion....
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 she'd have been blinded. Scary shit, and the biggest noise you never want to hear coming from a kitchen.
here are some closeup photos of the pad damage.
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.
Thats an explosion! Light bulbs are filled with an inert gas. Otherwise the filament evaporates too quickly.
Try heating a light bulb over a gas flame. A Vacuum tube will suck the melting glass envelope in, but light bulbs actually explode!
I know this because I actually have seen it tried, and the hot glass from the bulb actually burnt me badly. (Then came the research into why it exploded!)
LightBulb
(Yes, the blog is named after the flame trench at the pad)
Yes the damage is unusual.
http://www.floridatoday.com/apps/pbcs.dll/section?category=PluckPersona&U=5064da92e6c8480c8704375ba20ac620&plckController=PersonaBlog&plckScript=personaScript&plckElementId=personaDest&plckPersonaPage=BlogViewPost&plckPostId=Blog%3a5064da92e6c8480c8704375ba20ac620Post%3a9456250e-7da5-4cbe-89e9-c43a238970f1&sid=sitelife.floridatoday.com
We used 4000PSI concrete when forming the promenade (walkway around ~themiddle of a stadium) of the Yale Bowl in 2006. 3000PSI is some low grade shit, we were using that on fill ins only, almost all slabs I've ever been on were 4000PSI, so I have to assume that the shuttle pads are atleast 6-7000, bare minimum.
Stage lights are the best, if you leave so much as a finger print on those while you install them they'll explode when you turn them on. Other then that they get hot enough that old ones I pull out will have very large bubbles in them.
I may agree with what you say, but I will defend to the death your right to face the consequences of saying it.
Yup. The oil on your fingers is enough to set 'em off, pretty much. Latex gloves and a microfibre cloth are pretty much standard issue for changing bulbs where I work, though we've got a 20 year old lighting stock with 2,000W Strand Cadenzas.. :p
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