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I was fortunate enough to have a presentation, when I was in Elementary School (Golden Elementary in Placentia, CA), that featured bringing in Shuttle Tiles in the 80s. They put a blowtorch to once and let us touch it, right after. It was mildly interesting for a 9 year old.
Meanwhile, a bunch of my classmates junior year of high school took a tour of my future alma mater and came back with stories about how the thermite demo went wrong and exploded.
Later I saw black and white video of the same classroom, the thermite set the projector screen on fire ( which for some dumb reason was down at the time), the instructor panicked and pulled the screen causing it to retracted.
This did not put out the fire.
Unfortunately the video cuts out there. The building did not burn down, apparently, but I would have liked to have seen the full saga.
I almost skipped chemistry class the day they did the thermite demo for us. Instead I sat way in the back.
A teacher at my highschool did the thermite demo over a large ceramic dish, it shattered the liquid iron blob burned through the floor into the classroom below
They came to the schools in Portland, OR, as well and did the same blowtorch demo. Loved it.
Came to find out just a few years ago that my aunt, who is retired from NSA/CIA/Rand, was one of the people who translated the Soviet shuttle plans and helped discover that they were stolen from the USA. Apparently she was also involved, somehow, in every stealth program up until she retired. Exactly what she did...don't know, and she wouldn't elaborate.
The shuttle main engines were all tested at Stennis Space Center in southern MS (the same test stands were used to test parts of the Saturn V for the Apollo missions). I got to see a bunch of the tests as a kid, it was really something - always wanted to see an actual launch, but the closet I've come is catching a glimpse of the Falcon 9 from San Francisco in 2018.
Yes, i think the guide is saying it backwards. The caption of the video says “ Space Shuttle thermal tiles conduct heat so poorly that after being in a 2200 °F oven for hours, you can pick them up with your bare hands only seconds after they come out, still glowing hot”
This makes sense - the tiles themselves are at 2200 degrees but are not transmitting the heat quickly to you while you touch them for a brief period of time.
Yes. Same idea as when you stick your hand into a 400F oven to pull the pizza out. Doesn't hurt because air is a poor heat conductor. But if you touch the 400F metal pan, it will hurt.
Correct. Similarly, even though space is terribly cold, you could be exposed to it briefly without getting cold. Low pressure however is the real danger...
Which is also why cooling things down in space is a unique challenge. There’s nothing to carry the heat away from whatever it is you’re trying to cool.
The outermost part dissipates heat quickly to the air which lowers it's temperature (the temperature of the outermost part, that is).
In regular materials, the heat flows quickly from the center, so the temperature of the outer layer cannot drop significantly in such a short amount of time.
But this material conducts heat so poorly that this doesn't happen, so the outer layer stays cool.
At these temperatures, radiation is usually a much more significant heat transport mechanism than conduction or convection, so probably a substantial amount of that heat was deposited in the walls of the room and the bystanders.
Plus the have a very low heat capacity. So although they might be 2200F, they hold very little heat.
Similar to being in a sauna. A human can stand inside a 150F sauna without getting burned (the air doesn't hold much heat and slowly transfers it to your body). But if had 150F water against your skin, you'd be burned quite quickly.
We included fragments of a flown Shuttle tile in our Fourth Edition collection. The material is crazy difficult to work with. It powders under pressure. You obviously can't use a hot wire to cut it either (ha, ha).
As a kid, I was involved in NASA's Junior Astronaut program around the time of the Challenger disaster. I will never forget the presentation where they had us hold one of the heat shield tiles in our bare hands while they blasted it with a blowtorch for several minutes. It just blew my mind that such a thing was possible.
Looks like a great material to isolate a house and save heating money. Also great for saving air conditioning bills in desertic areas. If is just silica, why is not being sold yet? NASA could have stored some slighly defective or second grade quality blocks, unfit for space shuttle but waiting for a second life.
Producing aerogel is not easy. It's "just silica" in the same way that a diamond is "just carbon".
The regular house insulation already works pretty well, and heating is not incredibly expensive. Aerogel would have to come way down in price for it to make economic sense.
I'm still trying to figure out how to manufacture enormous quantities of lighter-than-air SEAgel in different flavors and colors, to solve the world's hunger and food delivery problems in one swoop. Edible SEAgel blimp drones!
>SEAgel (Safe Emulsion Agar gel) is one of a class of high-tech foam materials known as aerogels. It is an excellent thermal insulator and among the least dense solids known. SEAgel was invented by Robert Morrison at the Lawrence Livermore National Laboratory in 1992. SEAgel is made of agar, a carbohydrate material that comes from kelp and red algae, and has a density of 200 mg/cm3. SEAgel can be made lighter than air using hydrogen, causing it to float or hang in the air. It insulates against temperature, noise, and electric current. SEAgel is also completely biodegradable, as it is made entirely of biological material and can even be eaten.
Neat. I've played around a bit with a kit of different densities of aerogel made by Philips, crazy material properties, especially on the less dense end of the spectrum. The lightest was something like 3% glass by volume, eerie stuff.
>Aeroeggs from Aerogelex are unique aerogels made from hard-boiled eggs. While many people think of space-age blue holographic solids made of silica when they hear the word aerogel, aerogels can actually be made from a wide variety of substances including biopolymers such as those found in eggs. Aeroeggs are made through supercritical drying, the same process used to make other aerogels, just using boiled eggs instead of silica or polymer gel precursors. Boiling an egg causes the proteins in the egg to denature and link together to form a gel matrix that contains water in its pores. Once the inside of the egg has congealed, the shell is removed and the boiled egg inside is soaked in ethanol to replace the water in its pores with a non-polar solvent that is compatible with supercritical drying. After soaking the egg is put in a high-pressure vessel and the ethanol in its pores is extracted with supercritical carbon dioxide to make an egg aerogel.
>Aeroeggs are made from ordinary chicken eggs but are about half the size of a typical hard boiled egg due to contraction of the egg protein network when the water in the egg is replaced with ethanol and carbon dioxide. Density is approximately 0.6 g/cc making Aeroeggs approximately 50% air by volume. Aeroeggs absorb 3x their weight in water to irreversibly rehydrate back into regular hard boiled eggs.
While the tiles do have in common with aerogel that both are comprised of amorphous silica and air, they are different in many other significant ways. LI-900 is 6% silica by volume, the rest being air; silica aerogel is typically 0.2%–0.5% silica, but has been made with densities as low as 0.1%. LI-900 is opaque; aerogel is transparent. LI-900 can be "plunged into water without damage", even when hot; some silica aerogels will simply collapse if exposed to water, while others have been treated to make them hydrophobic and will probably just break into pieces. Aerogels are usually fairly isotropic, while LI-900 is anisotropic, like felt. Aerogel is made from hydrogel by supercritical boiling — at the time of the STS design, supercritical boiling of ethanol, a process that had resulted in a number of serious industrial accidents, but nowadays of CO₂, while LI-900 is made by dispersing spun glass in water, pressing it into blocks, and sintering.
So it's not the same thing at all, even though it's made from the same raw material.
The "don't touch the edges, just the corners" had me a little worried. Visitors don't always pay attention. I wonder how hot the parts you weren't supposed to touch were.
Heat is not that important in this context it’s energy transfer between the block and your skin that’s at issue. Holding onto the glowing bits may eventually cause burns, but you’re reflexes are to let go very quickly. My guess is the real risk is someone dropping and thus breaking them.
Most of the cool properties of these aerogel-like materials is that they are 90%+ air. Silica also has a relatively low specific heat. So, even though the material is very hot, there is not that much heat energy. There is more heat in a cup of coffee.
Not to mention, there isn't that much heat to speak of. At 2200℃, it should have about as much heat energy vs. ambient as a cup of 80℃ coffee, while being poorly conductive.
You could probably set something on fire, but not just anything.
The material is fine, this demonstration is hilariously bad. This demonstration could be done with a block of wood. Take a blow torch to a block of wood that size and pretty much the same result.
(I wonder if this ultraporous stuff could be used to make a emergency mask. It seems clear that is not easy to work with, but... Looks like a giant filter for a machine)
If you think of it like a bunch of cells like minesweeper, where the temperature differential is a function of #of neighbouring air cells - corners are going to cool much faster!
My first guess would be less surface for contact, thus less heat transfer. But the corners are also colored differently, I'm not sure why that's the case. They probably cool down quicker?
I assumed the color difference is just that they are actually cooler, so yeah, they cool down quicker. And not just "quicker": the difference must be huge in order for it to be completely safe to grab the corners and actually dangerous to grab the faces. But why?
> Space Shuttle thermal tiles conduct heat so poorly that (...)
This is nitpicking but it seems odd to use a negative value adjective like "poorly" as if high thermal conductivity would then be "excellent", instead of just saying something neutral like "low heat conductivity". I don't know, it just struck me as odd.
Sure, but in the case of copper you want to conduct electricity, so it makes sense to say that it conducts it "well". In the case where you want to avoid head conduction, like when re-entering the atmosphere, you don't want heat to be conducted, so a "poor" conduction is actually "good". I thought it sounded a bit odd, but since I'm being downvoted I'm assuming not many people agree, I thought I'd just point out that I thought it was interesting and/or caused some dissonance for me at least as a reader.
That's my point. If you're designing a suit that should stop yourself from being electrocuted it sounds weird saying that copper has "excellent" conductivity, it's not really excellent in the context you're talking about.
"Copper has excellent conductivity therefore it wouldn't be a great material to make a suit out of if you want to stop yourself from being electrocuted... You'd want a material that was an excellent insulator!"
That's a funny term, and that's kind of what I'm talking about, as a reader it causes discord to me when positive adjectives are used to describe something that is unwanted, but "misconducting" heat is an example of exactly what you want to happen in the scenario.
