What Really Happens During Atmospheric Reentry?
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- čas přidán 22. 01. 2017
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You should use the word compression more. When air can't get out of its own way it crowds together. When air compresses, it gets hot. At Mach 25 the air is so compressed that it is so hot the air is no longer transparent and its heat allows it to glow. It is the hot air that gets the heat shield hot.
That's the important thing you should have mentioned. It is NOT the heat shield that heats the air.
If it sounds like I said the shield heats the air then that's just awkward wording on my part... I know that's not how that works! Sometimes I really wish I had an employee to hear those awkward phrases for me!
Is it possible to re-release the same video with corrections, the next day.
Put out your first take with a note that the final one will follow.
Newsletters work that way. The first few downloads are those that correct it for the rest.
An employee, or a volunteer. Huh? Oops. I think I just sent a stamped of volunteers your way. Sorry about that....
Walter Clark A related point is that aircraft and spacecraft do not fly through the shock waves that form in front of them. Shock waves are always with the aircraft at supersonic speed. Some popular movies and other sources give the impression that sonic booms are somehow associated with breaking the "sound barrier" or breaking through shock waves. Sonic booms are merely the effect of shock waves an aircraft is continuously producing in supersonic flight. Sonic booms are continuous, too, but travel with the aircraft.
Walter Clark It is a bit of a chicken and egg problem. The heat shield compresses the air. Compressing the air heats it. Some of the heat from the compressed air is transmitted, by conduction and radiation, to the heat shield.
Every time I watch Amy's channel I learn something new.
Air compression is why Quicksilver's crowd-pleasing scene in his first X-Men movie was completely, utterly unbelievable. Seeing him move that quickly in a closed room without his immediately destroying the entire building in a massive explosion should be like seeing Spider-Man lift a skyscraper one-handed. Your brain should say "nah ah, no way" but instead people just think, "Wow, he's fast." It goes to show that our intuitions are seemingly hard-coded for low-speed systems that our ancestors encountered on a day-to-day basis, and why people's intuitions have even more problems with relativistic velocities.
Amy it's not fair they are giving you a hard time about the science. You have repeatedly told us you are not a scientist but a historian. Don't let them get to you. We love you and your work.
The phenomena described here is known as the "ideal gas law" in scientific circles. The ideal gas law describes how a mathematically ideal compressible fluid (a gas) behaves as its pressure changes.
To cut a long story short, the ideal gas law states that when you pressurise the ideal gas, its temperature increases. Conversely, when you decompress a pressurised ideal gas, its temperature drops. The more violent or prolonged the compression or decompression, the more pronounced the temperature change.
Actual guesses don't behave exactly the same as the ideal gas, but for all practical purposes the behaviour of real gasses is close enough.
This applies to aircraft and spacecraft moving faster than the speed of sound, because in subsonic flight the gas is capable of flowing smoothly around the object that's passing through it (subject to aerodynamics, of course). But when you hit supersonic speeds, the gas compresses more than it flows, forming a bow shock of compressed gas. The compression heats the gas which in turn dumps its heat into the aircraft. At hypersonic speeds the heating is so extreme that the gas breaks down into a plasma, just as Amy describes in the video.
You don't have to travel at hypersonic speeds in order to experience the ideal gas law for yourself though! All you need is an aerosol and/or a bicycle pump. Just hook the pump up to a bicycle tire and inflate it as you normally would. After a while, you'll notice that the barrel of the pump is getting quite hot. If you pump vigorously enough you might even be able to get the pump hot enough to be quite uncomfortable to touch.
As for the aerosol, just spray it constantly for a minute or so. The gas in the can decompresses and you'll feel the can cool down in your hand. Condensation and even ice can start to form on the can's surface if you do it for long enough.
LOL!🤣
@@suekennedy8917 I agree.
@@cl604driver Its not "ideal gas" its compressible flow. Air is considered incompressible uo to 300 feet a second, at higher speeds the compressible equation are used. Stagnation temperature and "aerosol" spray uniform state uniform flow...LOL!!!!!😁
@@suekennedy8917 I looked at what they wrote and snickered. Someone answering a question no one asked to show how smart they are and in reality showing the opposite.
Amy, for someone clearly too young to remember Mercury, Gemini, and Apollo you do a remarkable job explaining how things work. I was around during those 3 programs. But you fill in the gaps. Tell those folks who get annoyed with you if they think can do a better job than you then they can give it their best shot. Great job young lady. Keep up the good work.
Wow I never knew that was how a sonic boom worked that's so cool! Thanks for the awesome vid Amy, you never disappoint :)
The sonic boom isn't so much the plane breaking through the piled-up molecules; a sonic boom is not an event that occurs at a particular moment from the plane's point of view. It occurs when the shockwave from a supersonic object passes by the observer. You could think of it as a super-extreme form of Doppler effect. Just like with a Doppler effect, nobody on the plane perceives the sonic boom; it's the stationary observers that perceive it, and they all perceive it at different times.
One thing that people frequently misunderstand is that most of the heating is NOT caused by the _friction_ of the air passing over the capsule. What actually happens is that the air/plasma in the supersonic shockwave ahead of the capsule gets very, very hot, and that heat _radiates_ back onto the capsule.
The amount of patience you have for people in the comments section is nothing short of Mother Theresa level. Not only on this video but in general. It’s appreciated.
I saw the wood heat shield video, too. Being a woodworker myself, I'm not too surprised someone actually used it, even if only experimentally.
never get mad with Amy 😍
I really do appreciate how you explain things and how you cover things in your show it's really nice it's rare thank you
In the early days, (Mercury, Gemini, Apollo) this super heating of the air near the capsule would cause an ionization blackout, which would block all radio transmissions both to and from the capsule. This made for some exciting times for the ground controllers during re-entry. I really enjoy your videos.
A little about the "bow shock" Amy mentioned: I think most people would pronounce bow like the bow of a ship since many scientists who study sonic shockwaves start by learning the physics of a bow wave that a ship produces when a vessel travels faster than the wave speed of water.
Really interesting
I WAS GONNA SAY THAT!
John Hunter Every male subscribers of hers probably has a crush on her or something.
totenkopf999 Dude, stop it.
totenkopf999 Shut up and grow up kid. We don't need people like you here.
You sound just like an anti Trump creep.
Actually there was another supersonic passenger jet, the Tupolev 144. It was inferior to the Concorde in most ways and didn't last anywhere nearly as long in commercial service. The 144 does however hold the distinction of breaking Mach 2 before its more famous rival.
+Izayuukan True, but the TU-144 was always the faster of the two. That's why NASA once spent a small fortune to refurbish one of the retired planes, and literally cover it with sensors for high-speed atmospheric research.
Hi Amy, I really enjoy the work you do! Just to clarify, the Concorde was technically the 2nd supersonic passenger aircraft to fly, the first being the Tupelov Tu-144 "Concordski" (ok, not the official name, but I prefer it :D ) although the Concorde did beat the Russian plane into service.
Fun fact: the shuttle wasn't the only thing that NASA steered during atmospheric entry. They were able to steer Curiosity on entry into the Martian atmosphere by unbalancing its gum-drop capsule and then use reaction jets. Because of this mission planners were able to nearly bulls-eye a much smaller landing ellipse.
they also steered the Apollo capsule
Thanks for another great vid Amy. Keep them coming!
Amy thank you. I have no more questions.
Right, I've got to pull you up on the shockwaves too! The "sound barrier" as you used it (as in the aircraft gets through it... and presumably comes out on the other side? There's a little ambiguity here...) is the transonic flight range. This occurs when an aircraft (or other object) flies fast enough for certain parts of the flow structure to reach or exceed the speed of sound (i.e. break the sound barrier). This happens because displacing the fluid also accelerates it around the object.
When these pockets of air go supersonic they radically change the forces acting on the surfaces at those particular spots. Often these changes result in motion which causes the conditions that formed the shocks to temporarily subside and then once the extra forces and moments are gone and the body has returned to normal - reappear. This is the aerodynamic basis for wing flutter in transonic aircraft (though flutter is also a structural problem).
This instability of flow in the transonic range is what causes aircraft to violently shake. The shape of the shockwaves at that stage represents the greek letter lambda, hence their name - lambda shocks. They look more or less the same way regardless of which surface they occupy (be it wing, control surface or engine nacelle) as long as flow is attached under normal conditions.
The front of this lambda shock is fairly weak, it's a curved shockwave behaving mostly like an oblique shock. Oblique shocks are generated by sharp or blunt bodies and as a result are at an angle to the flow direction (hence oblique). The shockwaves are fairly weak because very little change occurs inside them, usually resulting in supersonic flow at both ends when traveling faster. Since these shocks are fairly weak, they're of no concern at that stage.
The back of the lambda shock consists of a normal (as in perpendicular to the flow direction) shockwave emanating from the body and transitioning into an oblique shock that curves forwards. The two subdivisions are in truth just one shockwave, but since the behaviour is so different at different locations it makes our lives easier to split it up. That normal shock can become quite a problem for an aircraft. Depending on how much curvature is present, it can grow until it comprises the entire aft end of the lambda shock. This is a problem because a normal shock forcibly reduces the Mach number behind it to a subsonic value and the faster the oncoming air is going - the slower it comes out of the other end. This makes them very strong and generally means they're bad news. When these shocks get stronger they begin to mess with the boundary layer and at a certain point they're enough to cause total flow separation right at the shock.
This phenomenon is known as shock stall and it does several things. First it adds drag. The lambda shock does that anyway, but separation behind it makes it worse. Second - it dramatically reduces the wing's lifting potential and changes its pitching moment (thus causing flutter when strong enough). Finally, the separated boundary layer creates an area of very low dynamic pressure behind it (fancy way of saying slow air I guess) which means that any control surfaces behind that shock (and therefore in that wake) are effectively useless. This is why supersonic military aircraft tend to use whole-body elevons, where the elevators in the tail section comprise the whole horizontal stabiliser and can be moved independently for roll control.
This problem is particularly pronounced with higher thickness and camber aerofoils, which is why transonic flight was a very major problem in the early days of high speed aviation. This problem is in fact what brought an end to some very early high speed flight testing done by the Russians. Yes, they went transonic first. It happened using a demonstration aircraft fitted with rockets for extra propulsion, but they abandoned it after a pilot engaged the rockets in a dive, went transonic, lost elevator control and crashed into the ground. It was deemed too dangerous and all the equipment was mothballed.
The solution was I believe formalised by NASA in the form of supercritical aerofoils. These are flatter and thinner, generating weaker shocks and therefore delaying the onset of shock stall and flutter. The Boeing 777 was the first US produced airliner to use a supercritical aerofoil which gave it an edge in speed.
Thx a lot for the subtitles
You are awesome Amy!
Lots of compression basically. Biggest misconception is the heat is caused by friction rather than compression.
I was taught in grade school that impact is a type of friction.
did they also teach you that diamonds have a high intrinsic value? XDDD
like clapping your hands, there is only friction from your hands rubbing onto each other but not upon impact
Yes isentropic heating of the air molecules due to compression is the primary reason for heat during re-entry. However there's also a component of heat from friction, which also contributes to aircraft or spacecraft tempature at high or hypersonic speeds in the atmosphere. The spacecraft slows in lower atmosphere due to friction priducing adiabatic heating, but at much lower temperatures than initial reentry.
That's why internal combustion engines compress the fuel/air mixture to get it hot before combustion.
Generally in aerodynamic heating most of the heat is caused by compression not friction.
Great vid as always Amy!
Correct. The heating is caused by adiabatic heating.
That makes a lot of sense. Thanks!
In a general sense this is to do with the conservation of energy. As air molecules posses kinetic energy (we experience this as heat), if they are compressed into a smaller volume, for a brief period, the same amount of kinetic energy in the initial volume exists in the compressed volume, thus the temperature naturally increases. It's not really related to aircraft breaking the sound barrier, although it becomes a significant problem at high velocities. If you quickly pump a bike tyre up to high pressure you can experience the same effect, as the bike pump will naturally heat up.
Thank you for this video!
Keep going Amy! You are getting smarter about the physics and explaining it. Science rocks.
Great job Amy. LAnother factor that has to be reduced is speed. At 17k mph you have to get down to zero and the energy of motion is converted to heat like the front brakes of your car. One thought is to come back in multiple orbits thereby reducing the heat over time. But NASA did not have the patience.
I was trying to remember what exactly happens during a shuttle reentry because I read it somewhere and forgot, so searched it over CZcams, I was waiting for a quirky animation video and the monotonous voice of a guy explaining me basic physics, but I did not expect that 😍
Great video, your content is always so interesting to watch. Keep up the great work!
Love you Amy!!!!
Shame on ANYONE who got "annoyed" at you! Who else presents these topics so well to so many folks in terms THEY can actually understand? AMY!... THAT'S WHO?!!!!
Ooo! Amy, I would LOVE to see a video on the potential heat-shield requirements of a mission to Europa! It's by far my favourite moon, and I think it to be the most beautiful as well. I know it has a very thin atmosphere, but Mars does as well and it requires a heat-shield, so I'm curious how a mission to Europa would compare!
Hello my favorite friend you did great on explaining everything.thank you.😘😘😘😘😘😘😘😘
great explaintion and great video!
another great video Amy. More please. 👍😁
Corrective note: Both Concord and the Tupolev Tu-144 were commercial supersonic passenger aircraft.
Did the Tupolev ever fly passengers? I don't think so.
Yes it did. en.wikipedia.org/wiki/Tupolev_Tu-144
Ok, you are right. Must be western bias. Not many flights though...
Definitely a baaad case of western bias. Gemini with "first EVA ever" and such. And "not many flights" in case of Tu-144 is a good thing: it was withdrawn before it could kill anyone - unlike Concorde.
Didn't the Tupolev kill some pilots on or before presentation and that is why they pulled back?
Well done.
Hi! really good video as always! Thumbs up for that!
I have a question, is the plasma around the capsule during re-entry what blocked radio communications?
Alberto García Engineer Yes, from what I understand. It was the ionization blackout and it was during that fiery part! I will need to research more to fully understand exactly how that blocked radio signals though... future video! Thanks for bringing that up. Yay!
Vintage Space thank you for answering! Keep it up! :)
The early Universe was opaque and light didn't travel far because it was so hot is was a plasma. Eventually the Universe cooled enough and electrons could bind with nuclei to form atoms. Those "soaked up" electrons allow the Universe to suddenly became transparent and light could travel long distances. We see this today as the Cosmic Microwave Background. Plasmas don't allow light (or radio waves) to travel very far. On re-entry, as you pointed out, the bit facing the Earth has a lot of plasma! Hence radio blackout.
Later on of course when we have comms satellites in orbit, things like the shuttle could continue to communicate with teh ground because the plasma was under it, Earth facing. You can still transmit to satellites above you which was how the shuttle kept a data feed going all the way down.
A plasma is conductive, so like a wrapping of tin foil tends to attenuate radio. I'm guessing the higher the velocity the more intense that effect is (which would explain the full comms blackout of the Apollo capsules vs the Shuttle which was able to retain a radio link through most (all?) reentry).
Joe, see my comment above, the shuttle used in orbit relay satellites to maintain the radio link. There's no plasma above it :)
I love vintage space paintings and drawings. I imagine that NASA must have had many graphic artist working for them. If this is true could you do a video on those artists.
I treasure my Skylab coffe cup that pictures Skylab with both its solar wings. You can find some good stuff at estate sales. Found 8mm film of Nixon in Libya shot within a few yards, 8mm film of Kennedy in his convertable at the USAF Academy Graduation just a few months before he was killed. Some vintage space poster explaning how the Saturn V stages functioned, and a set of Apollo 8 puzzles that were probably sold at the space centers gift shops.
Thank you for answering this... *hot* topic... hopefully this explanation will have helped stop any... *heated* discussions that may have... *flared* up...
...I'll show myself out now.
There were a lot of weird designs proposed for the first manned spaceship that weren't built. It would be fun to study how they dealt with reentry, especially the "Avco manoeuvrable drag cone."
I once heard the phenomena described as the air being subjected to super compression by the re-entry vehicle.
Where were you when I was a space kid during the 1960's? All I had was the library, three channels on television, and a few weekly magazines.
Great explanation. We used to regularly hear Concorde breaking the sound barrier in south west U.K.
I have the impression that when someone claims the moon landings were a hoax, you come down on em like a ton of bricks, you're so passionate.. Your BF/Hub is a lucky guy.
/!\ raging nerd below /!\
I feel you could have gone into much more detail here... You didn't even mention that it really is *compression* that heats the air up. You also glossed over how exactly the heat shields protect the spacecraft (the ablative ones mostly dissipate heat by sublimating, like a melting ice cube absorbs heat from a drink, while thermal soak is basically a large insulator that withstands high temperatures gradients without letting the heat conduct to the spacecraft).
You could have also talked about why the different types of heatshield are used when they are used. (Ablative for an aggressive entry, like capsules that have little to no lift, as they can handle a greater heat flux. However, they are dense and therefore too thermally conductive for shallower entry profiles : as the entry lasts longer, heat would have time to conduct to the rest of the spacecraft. So thermal soak was mainly used for things like the space shuttle, with thick, highly insulating tiles.)
And since this is vintage space, perhaps mention the now obsolete passively cooled system that was used on the mercury capsules.
Then again, this isn't a hardcore physics channel. And it would make for a pretty long video.
Love your content anyway! :-)
piranha031091 , the space shuttle was also too damn big to make the tried & tested ablative shield.
Ablative shields also emit gas as they decompose, that gas forms an extra barrier layer against the encountered atmosphere.
Ablators have a pretty low specific heat of sublimation, so sublimation itself doesn't really take all that much heat away. The main benefit of ablation of the heatshield is that overheated surface of heatshield is removed and blown away with the plasma, not allowing its heat to penetrate deeper through conduction - a non-ablative heatshield would be dissipating its heat into the structure of the spacecraft; and the crew compartment; ablative - is left behind as a plasma trail.
lots of love :) nice work
The entry is really hotter than you expect;) nice video entry
Nice explanation!
As always, nice summary.
PS love the cat toy poking our from the couch.
Don't mind people who get upset. You're doing a GREAT job! Plus, you cannot please everyone. That's a recipe for failure.
Be you, the world will adjust! :)
Thank you for mentioning the BAC Concorde. One of the greatest aircraft ever.
Hi Amy, I love your videos, I have a question, which were the tools that astronauts used in the apollo program? and how were this tools stored inside the landing module?
I once followed a lexicon to a pot of dictionaries at the end of a rainbough. I was in Canada. -Murphy (great info/vid, btw)
Nice explanation thanks for the info.
Amy, can you do an episode explaining the aerodynamic and control characteristics of the Soyuz compared to the Apollo and why the Russians and Americans tend to continue using their preferred shapes for re-entry capsules.
Hi Amy, thanks for the video. With Halloween coming up just wanted to mention that you could easily pull off the MK11 Skarlet look.
New to the channel. Love it that ur using vintage footage. Matches ur style ;D
Promise us if you ever decide to directly quote a comment which challenges a point you make - use the voice of the Simpson's comic book guy when you do, for the full effect. ;)
Peter Grenader or Krusty the clown. 😜
Either..would be..equally hilarious. (Comic book guy)
Mukluk!
perfect!
All good!
Thanks Amy for clearing up the air friction myth about reentry heating. You didn't really say why the air gets hot though besides friction. It's really pretty simple. The air can't move away fast enough because the capsule is moving faster than sound. This causes the air to compress and compressing air causes it to heat up.
That's why engineers sometimes call the faster than sound issues "compressibility" rather than shock waves or something else.
Keep up the good work!
It gets hot because the moving air has kinetic energy and as the moving air is stopped by an object its kinetic energy goes to zero and the internal energy goes up, i.e. it gets hotter. Look up stagnation temperature and compressible flow.
To help visualise ablation think of an ice cube. The outside turns onto liquid above 32° f and carries away the heat. The rest of the ice stays below freezing.
We could never really be upset with you for anything!
Great video and that shirt is way too cool!
Yep.....space capsule gets so hot reentering the atmosphere, yet at splash down into the ocean, not even the slightest bit of steam off the water
"Yep.....space capsule gets so hot reentering the atmosphere," - You appear to have disregarded the role of the word 'ablative' in 'ablative heat shield'. The part of the heat shield that get hottest boil/burn off and take that heat with them.
"yet at splash down into the ocean, not even the slightest bit of steam off the water" - How can you tell whether there is "slightest bit of steam" or not. At splashdown the hitting of the water is accompanied by the generation of white material that is ejected from under the capsule. That material may be water turned to foam by the impact, or it may be steam produced by heat, or it may be some of both. I don't see how you could have the data to tell either way.
You are also disregarding the air cooling that will be happening while the capsule descends hanging under its parachutes.
Thanks you .
Just reading some comments wow you really have to be careful what you say lol I don't think I could handle the stress !!! Good show Amy I love it
nice video thank you.
Great video very informative, hope you make more soon. Subscribed.
Love your work, Amy.
I have a couple questions. Could you explain the maneuvers the CM performs during reentry? I heard Jim Lovell mention in the commentary section of the movie Apollo 13 that the CM is a lifting body, while mission control screens show the flight path flattening out to near horizontal fora bit.
Also, in Apollo 11 movie, there's camera footage from the CM performing a roll during reentry. Possibly to adjust trajectory?
Thanks, Amy!
Ed.
You mean silica tiles not silicone which is a gel. They are silica ceramic tile, extremely light and brittle. So much so that if you rub a small piece between your finger it will turn into a powder.
Technically the heat shields are a gel IE an aerogel. They are made of silicon doioxide I believe.
and there's still a big difference between silicon and silicone, the latter being a rubber, gel or liquid usually. silica is usually used as a trivial name for silicon dioxide
Another great vid, Amy. Thanks!
One non-space question: That illustration on your tee-shirt looks familiar, but I can't place it. Details, please?
Great work! What editing software do you use?
My great uncle was the lead designer for the engines on Concorde
Amy, the Anglo-French Concorde was not the only commercial airplane to fly past Mach 1; so did the Soviet Tu-144.
Didn't the Apollo capsule make S-turns as well?
As I recall it, the fact that the capsule's weight was off center was so that you could steer it in the atmosphere by rolling it. And that was for the purpose of making short upward turns once the heat got too extreme.
If you haven't already, can you do a video about all the concerns NASA had about the conditions they might find when they landed on the moon? There are a number of tales about what they were, such as the lander sinking in feet of accumulated interplanetary dust and stranding the astronauts, but I'm interested in what the actual ones were.
There's only one person that could exit and renter the atmosphere and that is Superman .
You do an excellent job with your videos. Thank you. By the way, have you considered doing a tribute video about Capt. Gene Cernan since he died just last week? I know you have met him in the past. I was a reporter for one of the major newspapers in Chicago for several years and had the opportunity to interview him in 1997 for a long feature I wrote on the 25th anniversary of his last steps on the moon. We talked in person for over three hours. I have always found him to be perhaps the most articulate and lucid of the Apollo astronauts in speaking about his experiences.
I don't even have notifications on and I still saw one min after upload
In vintage days, my Dad worked at GE reentry systems where heat shields were designed for ICBMs like Atlas, Titan, and Minuteman missiles. Bombs and Spy Satellites haha.
I have always been fascinated with the re-entry process. Could you perhaps elaborate on why communications between the Apollo spacecraft/command module were knocked out during re-entry. Can you explain how NASA learnt about re-entry, the minimal corridor in which re-entry takes place and if any spacecraft NASA or international that have come close to not re-entering? ('bouncing right off')
Thanks Amy, love your work here and everywhere else online!
Thought on shock waves: they don’t really travel faster than sound in the medium. What happens is that the medium gets compressed next to the moving object, raising the speed of sound in that vicinity, to the point where it matches the speed of the shock, thereby achieving equilibrium between the energy coming into that boundary region and the energy going out.
In a gas, sound propagates at the speed of movement of the atoms/molecules. Therefore, simple heating will raise the speed of sound.
Also, sufficient compression of the gas could turn it into another state, not quite liquid, perhaps more “supercritical”, where sound can propagate more rapidly than the speed of the particles.
No one gets annoyed. We just want to learn correctly.
Request for a future Vintage Space:
A lot has been written about the Apollo LM having "Walls so thin you could poke a pen through them (sic)" Most of us space nerds know that is a gross over-simplification, but maybe you, Amy, can do a feature on this subject?
This is great! My question is what happens on the inside of the space craft upon re-entry? Does the inner temperature rise? Do the astronauts have to wear cooling suits or is it done through cooling the cabin? Or does the temperature not really effect them at all? Do they just get a bit sweaty and cool off once they're through?
Great video! The science of re-entry explained...simply captivating...
Also, very nice shirt! It looks like a vintage tattoo?! Really cool.
*you are so intelligent, and classy! THAT is as hot as re-entry!*
*respect* and much love, from Penn's woods, USA.
☀️😎☀️🇺🇸
The Mercury heat shield was Berylium and was a heat sink design rather than ablative - it was designed to absorb and radiate the heat rather than melt and carry it away. The nuclear weapons heat shields are similar.
Amy, I get the heat from the speed of re-entry. It's the thermosphere that has always confused me... very hot, but very small density so no capacity for heat transfer. I'd love to know if the thermosphere causes additional heating issues due to it's high energy level. Thanks for your vids.... love them.
You are fantastic! Thank Dnews for a new fan! #goodvibes
There's another subject that I would like you to talk about is the Apollo space suit which has a interesting story.
Alas, the good ole' fashioned wooden heat shield.
I'd love to see a video on the spacecraft cemetery in the Pacific.
Bow as in bow shock is pronounced like what an actor does on stage, not like what an archer holds. I just found your series and love it!
Just a small niggle on Shuttle tiles (I'll forgive it a bit since I know you said you don't like the Shuttle ;) )... that's silica, not silicone. There was a silicone-based adhesive used to bond the tiles with the felt pad between the tiles and the orbiter's skin, but the tiles themselves were made from silica. Thanks for another fun video!
Are there any cases of other "unusual materials" used for heat shields? The wooden heat shield was quite interesting to learn about.
It's conservation of energy. Kinetic energy (motion) is being converted to heat. The same thing happens when you apply the brakes on your car, you are converting the motion of your car into heat in order to slow down.