The physics behind the performance of rigidized ceramic fiber tiles like the ones used on the Shuttle, the X-37, and Starship is called Mie Scattering. The selected fiber diameter (~1 micron) is "tuned" to the peak wavelength in the heat radiation inside the tile at the highest operating temperature (~2400F), called the Wien Peak, which is ~1 micron for blackbody radiation at 2400F. Those thin ceramic fibers strongly backscatter that heat radiation and effectively block it from penetrating deeply into the tile thickness. The very thin fibers are made of ultrahigh purity quartz and have very low thermal conductivity. For comparison, the diameter of a human hair is ~70 microns. There are two parameters that characterize Mie Scattering, namely, the absorption coefficient and the backscattering coefficient. For the Shuttle tiles the backscattering coefficient is about 600 times larger than the absorption coefficient. Side note: My lab spent almost three years (1969-71) developing and testing rigidized ceramic fiber tiles for the Shuttle. My job was to design and build the lab equipment to measure the absorption and backscattering coefficients of those developmental tiles.
What determines the ratio of absorption to backscattering coefficient? If I recall correctly, absorption and emission coefficients are the same at all wavelengths because of detailed balance and can be calculated (in theory, anyway) from molecular or electronic structure. But what's the physics that underlies the backscattering coefficient? Is it just geometry and the dielectric coefficient of the material? Or is there something more at play?
@@QuantumHistorian A dielectric fiber (quartz) with diameter matched to the predominant wavelength of the thermal radiation trying to penetrate the tile and having very low optical absorption (high transmission) in the 1 to 4 micron waveband (the near infrared region).
I agree. And I imagine that anyone who worked on the development of the Space Shuttle heat shield who might watch this will feel a lot of gratitude. Although we have very little to go on, it seems like SpaceX have chosen to walk the same path, looking for better solutions that modern technology may have made available, but will ultimately conclude that chemistry hasn't really moved forward, and the solutions worked out by NASA decades ago are still optimal.
Completely different story when I fallen asleep in front of the wood stove outside. As I’m snoozing it gradually works its way up to a nice, uniform orange color and I look like a lobster when I wake up.
@@Real28 that's one thing I miss about my old induction stove. That and it'd cool as fast as turning down a flame on a gas stove. Whereas my current gas stove sure as hell can't heat as quickly as an induction cooktop. By the same token, I don't pay for gas in this apartment, it's included in the rent, but I sure do pay for electricity. So, I'll wait for the pot to heat up. Dad may have raised a dummy, but he didn't raise no fool.
Our now retired material and manufacturing science teacher has a heat shield tile from the Buran shuttle. He always brought some interesting objects to show during his classes. The tiles are incredibly light, which makes sense since air/empty space is a very good insulator. The outer coating was black and very hard and quite brittle, the inside of the tile was white. Couldn't see what kind of a fiber structure it had though. The outer coat had some damage marks which looked like he had done some Brinell hardness tests on it, but I don't remember if he told us the results. But it sure seemed like it could be very glass-like hardness. The story of acquiring that heat shield tile was quite simple. He went to the site where the Buran has been in storage for decades with some group, found the tile laying on the ground and just put it in his bag and hoped nobody would check the bags on his way home and across the border.
I own one of these Buran tiles as well, and they are really fascinating to handle. Even after handling it countless times over the years, when showing it to people etc, it still catches me off guard how light it is. It's like picking up a brick made of nothing. But at the same time, you can tell it is fragile - just by handling it carefully with just your fingers, there are little fragments that come off once in a while (like grain of sugar sized pieces, but still).
Excellent explanation Scott on how the "glass" tiles TPS works. Enough tech info to satisfy a nerd, but clear enough for a lay person to catch your drift.
Well, all of the TPS tiles have been silica based. The earliest, so delicate that one could, with a badly sprained hand, crush them easily by accident and were about as waterproof as the Titanic currently isn't. Later versions improved greatly on strength, which even now remains not much to write home about and waterproofing - which has improved tremendously. Discussing the things, as Scott mentioned, ITAR can be a royal pain in the gonads, with prosecution being quite aggressive and the regulations being so nebulous in some areas as to literally leave it open enough that one could cite someone for an ITAR violation for discussing the chemical formula for pure water. And given my military background initially involved intimate involvement in nuclear weapons, suffice it to say, we had a keen idea on ITAR regulations. That dated back to when even PGP encryption was considered a weapon.* *Entertainingly, an allied foreign nation had ordained that encryption, especially VPN's were unlawful within their nation as they considered the technologies weapons. Citizens and residents were rather stuffed, but banks explained patiently that there were three chances that they'd engage in unencrypted financial transactions, slim chance, fat chance and no chance and that they'd cease doing business within said country. Policies swiftly changed for some odd reason.
Speaking about the sapphire strands, it's actually really easy to make your own sapphire. You take aluminum wool and mix a ball of it with aluminum oxide and put it in a container that can withstand the heat and put it in an old microwave for a minute or so. When you pull it out, you have clumps of sapphire mixed in with the powder. It's the same process for maming rubies in a microwave, but with rubies you add 1-2% chromium oxide to give them their color.
Excellent and simple to understand. One correction: when you increase the thickness, it does simply "take longer" for the heat to get through, you double the thermal resistance, so you only get half the heat flux.
Hey Scott, good video. Sort of a review for me. I have two friends from high school. Who worked in that shop that remade those tiles that were unusable. One has moved on to Blue origin. The other works for SpaceX tile manufacturing in Titusville, Florida. I think that's where they're at. But they expanded greatly when starship started up. I think Mark was working 75 hours a week. Like I said before, good video. Thank you
That example of looking at a boiling pot of water and not burning your eyes (or face, hair, the surrounding skin, your shirt, the walls, the ceiling...) is a great example. I immediately understood just useful it is in this case that radiation is less effective than conduction.
Another great video. I work in the facility you showed, and I program the CNC machines that cut the tiles. It's really cool seeing video of people I work with. I didn't realize this video was out there. As usual, you are spot on with the details of how thermal protection works.
if anyone is wondering how different spacex tiles are from space shuttle , the only difference is that there are fibers of different cross sections in the mix and some small granules of various elements embedded into fibers Also the black coating flows more into material
Hackaday still has a picture from the video up of a Starship tile structure. I would presume the larger, denser fibers dispersed through the media are a compromise between strength, heat protection, and weight.
Also, they are much, much more substantial. Look how thick they are and with a mechanical fixing rather than the shuttle ones which break if you look at them, held on by glue.
@@mysock351C In general when one includes larger fibres in a matrix it's to improve the tensile strength of the material and limit cracking. A mix of different diametre fibres can also get you to a lower density for a given strength than a constant density. So it's not particularly surprising.
@@Shrouded_reaper The one advantage that Starship has is that does a belly-flop back into the atmosphere. One of the things that arguably doomed the shuttle was the requirement that it be able to fly (more aptly glide poory) back all the way to the surface. It couldn’t afford much extra weight, and the shuttle tiles are quite light. Starship on the other hand is more brute-force, so they are likely able to accept the added weight and reduced thermal performance that comes with having a mixture of fiber diameters in the mix for reinforcement. It can just come back more or less ballistically to the landing site once it’s slowed down enough.
ITAR is no joke. Glad you checked. Wonder if a plumber's soldering blanket could help? ~2,300 degrees and cheaper than dirt. 17cents a square inch retail.
ITAR can be odd. A microscopic pic might get you in trouble? Yet the tiles themselves are available on eBay. I'm sure the Chinese bought some early on and have studied them under their finest microscopes. IIRC after OFT-1 some were gathered from the beach and hadn't been in the ocean.
There are space rated similar blankets, but I don't think they temp range is quite high enough. Much of the white 'tiles' on the shuttle were FRSI (Felt Reusable Surface Insulation) that look like a quilted blanket. If something similar could be developed in a high enough temperature range, it would remove the problem of the fragile tiles.
The heat isn't particularly hard to deal with on its own. The main problem is that plasma at those velocities can strip out individual atoms and molecules, so the surface material has to be extremely chemically stable at an extreme range of temperatures while also being strong and rigid enough to protect the insulating layer.
I remember going to the kennedy space center and midway thru the tour i seen an example of how a heat tile works ! It was heated red hot and tossed at me ! I caught it and it was cool to the touch and i got to keep it ! Then my sister stole from me when we got home !
@@penguin44ca I found a video of this demonstration at KSC on youtube. Search for "Space Shuttle Thermal Tile Demonstration". They encouraged people to come up and pickup the glowing hot tiles. What the OP described is not a stretch. Sounds believable to me.
@@penguin44ca That may not be on the public tour, but he may have been someone's kid and gotten a VIP tour. Based on his grammar, it was probably a senator.
The heatshield is why the spaceshuttle never got rapidly reusable as they had hoped. It simply took to much time to refurbish it. But with Starship they have proven that they can replace the heatshield in litteraly no time so I imagine that alone will make a difference.
@@JohnVanderbeckbut it is a joke. "No foreign bad actors know about this because we said they are not allowed to know about it" They know. It'd be very naive to think otherwise.
NASA recently announced the development of a new lightweight alloy with enhanced properties meant to withstand extreme conditions including heat and cold. Referred to as GRX-810, NASA has already selected several companies to produce and market use of the product. From what I could see of the tiles, they have a thin metal "plate" inside each tile that clips to prongs welded to the Starship. I'm convinced that use of this new alloy or something like it will resolve the problem. I don't think making the rocket out of the metal alone will fix the problem but a tile, with or without underlayment, might work. The ceramic itself break apart under certain conditions and cannot be relied on to do the job. What SX has done so far is provide a short term solution to get the Starship airborne and home again. NASA may already have a solution in hand.
Very good video. The only thing that is radiation heat transfer is not about the temperature, it is about the temperature differences so as the tile heats up, the radiation heat transfer slows down
Back when the Space Shuttle was flying I recall seeing a research paper about using multi layer corregated titanium instead of the silicon tiles. Supposedly it would be more resistent to wear and tear. Anyone know what happened to it? Was it less resistent? Did it cost more?
Highly underrated, ridiculously informative, and downright entertaining. This is one of my fav channels on YT and I wanna thank you so much for sharing Scott! 🫡
Yes, I think you are right about heat shielding being the main problem for making Starship rapidly re-usable. The Space-shuttle was intended to be rapidly re-usable - but it never happened!
Booster needs to be rapidly reusable. Ships? Not so much. You have 10 ships in rotation running on 2 or 3 boosters. (tankers for fuel to LEO, primarily). Crewed starships will be a tiny fraction of ships launched. The same folks who believe the same starship combo (ship and booster) will fly the same day are the same folks that believe that starship point to point will actually happen. The vast majority of starships to mars, for example, will not be coming back. Folks don't understand how the program will operate.
@@KnugLidi the main factor will be cost. If it takes too long or too much working hours it becomes to expensive. So the ships in fact need to be rapidly reusable. We can argue about what is "rapid", but it definitly is the critical factor.
@@teshtrion7860 Consider the use cases. Ship to LEO for cargo deploy - cargo loading and integration will limit reuse. Ship to LEO crewed - tiny percentage of usage, if any in short term and not high operation rate. Ship beyond LEO - that ship likely single use. Lunar cargo will be rare and likely would be single or limited to leo-luna-leo runs. Fuel to LEO - this is the case with the likely highest need for reusability, but this only applies for flights beyond LEO which are going to be the exception rather than the rule. Starlink to orbit, second highest use case in medium term, several flights a week, but not necessarily on same ship. As for Mars, due to the limited windows - long periods with no flights and a flurry every window - will be limited due to the lack of paid missions and will be 4-5 windows before the idea of launching a squadron of ships in the same window.
Its very obvious how delicate and soft the material is from the clip at 7:20 showing the worker removing the silicon 'sponge' from the furnace as you say "to give it some strength" you can see an impression from the hand of the guy who picked it up, its that soft.
Thank you for reminding us all that NASA and SpaceX have worked together to use materials science advancements that occurred as a consequence of the experience gained during the decades-long Space Shuttle program. As always, you stand head-and-shoulders above most of your peers because of technical deep dives such as the one we had the pleasure of receiving in this video.
Another episode on how they're attached would be fun, as it's super interesting! If memory serves, the Space Shuttle had Inconel pins embedded in them and then an Inconel fixture on the aluminium frame, so even the fitting was a high temperature and high thermal resistance piece!
How is this different from asbestos insulation? I thought the reason asbestos was so dangerous was because of how small its particles were. Wouldn't flying ships covered in this stuff cause respiratory issues?
For those wondering why ITAR wouldn't want information disclosed about heat shields, its because passive heat shields are essential for accurate ICBM reentry vehicles. If you use ablative heat shields on the warheads, accuracy will reduce.
All modern reentry vehicles used by the US have ablative heat shields. They ensure accuracy by spinning the reentry vehicles to prevent uneven ablation effecting accuracy, plus in the Trident D5's Mk.5 reentry body they have metal filaments running along the axis of symmetry to make ablation more predictable.
Do you know anything about the heatshield that the X-33 was going to use? I found a picture from the air and space museum, presumably the back side of the tile (can find it searching for this -> NASM-A20060281000_PS03). It was developed by BF Goodrich (tire company?) and used Inconel. I'm not aware of that design finding its way onto any other vehicle.
I spent time during 1995-96 developing and measuring the insulating properties of a half dozen heat shield concepts for NASA's X-33 under contract to NASA. That Goodrich Inconel thermal insulation panel was one of those concepts. Inconel has a maximum use temperature around 1800F. The maximum temperature on the Space Shuttle tiles was ~2400F. So, those Inconel tiles are a lot heavier than the Shuttle tiles and don't have enough high temperature capability. Lockheed was convinced that its Venture Star X-33 vehicle could fly entry trajectories that kept the peak temperature below 1800F. We will never know if that vehicle could have performed that feat because NASA canceled that over budget and behind schedule program before any test flights were attempted.
Metallic thermal protection systems based on superalloys, like the one planned for VentureStar, seem understudied. There are a few papers available online by Blosser et al.
I fully agree with you … the TPS has to be the biggest challenge. Thinking back … although shuttle used ceramic tiles for the major extent of airframe protection, didn’t they use reinforced carbon-carbon panels for wing leading edges …ie; those parts which needed thermal protection but where the local loading environment was more aggressive than the ceramic tiles could withstand?? Yes … I am thinking about the same parts that proved vulnerable to impact damage from chunks of closed cell foam being shed from the main external tank. However, I assume this material could be manufactured in appropriate geometries that could offer good thermal protection to those parts of Starship (flaps) that proved challenging based on FT4. Sadly, I am not sure about the thermal properties/performance of this material and I suspect it comes with a weight penalty … but it might offer a potential compromise solution?? I believe RCC composites are good to >2000C with breakdown by sublimation at >3500C. I have also wondered if exposed parts of Starship airframe could be fabricated from inconel alloys to provide for superior integrity in exposed locations such that they might still perform adequately with reduced thermal protection. Maybe a combination of localised use of Inconel structure with RCC cladding?? Has anyone looked at the potential of a hybrid panel of ceramic matrix core laminated into an RCC structure? … similar to a typical honeycomb panel? … though probably find the matrix would be crushed in the lamination process ☹️. Just some wild thoughts and speculation from a retired aerospace engineer ….
One minor correction: alumina (Al2O3) is only called sapphire in a specific crystalline form (the alpha phase). I'm pretty sure this would be amorphous alumina, which is definitely not sapphire. Other than that, great and interesting video!!
@@Shadare I know spacex worked with NASA on the pica-x heat shield but not Starship. Since each TPS is unique to each vehicle I'm not sure how much data from the shuttle program would have been useful but perhaps some.
@TheEvilmooseofdoom Not starting from scratch designing the manufacturing methods is more what I mean. It would have taken a lot of time and money to re do all that engineering and I doubt that all 3 would share such stark similarities if they were designed by completely separate engineers not cooperating at all. NASA wants to see these vehicles succeed. They aren't greedily sitting on their patents waiting for everyone to fail. I think it's a little weird how resistant people are to what seems like such an obvious explanation.
I once saw a video of someone in the facility making those Spaceshuttle tiles pulling one of the tiles, glowing white hot, out of an oven using a pair of tonges. And then just picked it up with their hands without getting burned
If there's any loose tiles from Starship's re-entry, it'll be found on beaches between Perth and Broome. The bigger question will be, can Starships re-entry be seen from there? The current flight plan should have it visible from Diego Garcia and the cargo and fishing vessels that cross the Indian Ocean, plus maybe one other island group.
I feel like there must be an even better way to make heat shielding that we haven't discovered yet, some kind of materials science using crystals? We love crystals right?
Doesn't a ceramic heat shield slowly dissipate its absorbed heat over time? I think I remember that Shuttle needed heavy venting for hours after each re-entry so the orbiter wouldn't get too hot inside after landing. I wonder how this might impact Starship's plans for rapid reuse.
It doesn't let much heat through, and reflects as much as possible, but yes, all the heat it absorbs will come out at some point. You do get to take advantage of convection to cool while you're on the ground, though.
Ceramic fibers can actually be surprisingly flexible depending on the chemical composition and production method. The TPS tiles shown in the video are specifically made to be rigid through extreme compression and heat/chemical treatment. You can also combine ceramic fibers with heat resistant polymers like Kevlar to make composite textiles
Is there a spray on ablative ceramic coating that could be applied to outside of the existing Starship ceramic tiles that could be reapplied between flights?
I've been looking forward to you doing a video like this. Space X's approach for this up-coming test flight looks like a sticking plaster, literally, when you consider they're using a layered technique of ablative and non-ablative materials. Hardly an easy process to replace quickly between flights! But that always learn a lot with their fast experimental approach. We'll see!
@@TheEvilmooseofdoom yes, it sure is. But you can't reuse an ablative layer if if ablates. If the other tiles stay put, all well and good. It's just a stretch to imagine that the under-layer will not be affected. We'll be see. I hope I'm wrong!
@@xehpuk I thought it did serve purposes other than “flexing” for the US? Like payload and crew rotation on the iss/mir. Also, the boosters were reused, the main orange tank fell into the ocean. The boosters fell back to earth with parachutes which allows them to survive.
What was that stuff called that some guy claimed to have invented? Starlite? It could withstand high temperatures on one side whhile staying cool on the other.
I believe that Starlite falls into the category of ablative shielding compounds, as the outer layer would char, protecting the what's underneath from excessive heat.
I think the high temperature capability of stainless steel may not amount to much payload benefit for Starship in the end. Having very hot interior surfaces isn’t really acceptable for your payload, especially the human type, and generally a bad idea around LOX. It is more robust than aluminum, but apparently neither the Shuttle or Starship was “robust to loss of a single tile” - hence the ablative layer. It will be interesting to see how the two typical heatshield sections finally compare on lb/ft2. Presumably Starship will eventually be more reliable than the Shuttle, but perhaps not much lighter.
@@linecraftman3907 Yes, that may have been lucky though. Elon said "not robust to loss of a tile" I believe, so maybe if tile loss occurred somewhere else it would have been more serious - e.g. payload pay, LOX tank, ??? In the end they have elected to add the ablative layers to improve reliability, but this also adds weight. Provided none of the heatshield fails the steel temperature may never be much higher than the Shuttle aluminum temperature (and so about the same weight) - it will just be rapidly reuseable and more reliable.
@@marksinclair701 that interview was pre-flight iirc, in the post flight it became known that the steel iviewed from inside was glowing hot, so tiles were lost - ship was ok
@@linecraftman3907 I think you're right, but I don't think that changes the outcome. They decided to add the ablative anyway, and pay that mass penalty. Red hot interior steel might be acceptable in the skirt or an empty payload bay, but I doubt its OK in an occupied payload bay or a LOX tank. Do you know where the tiles were lost or are these the ones they removed?
If replacing the heatshield is faster than re-waterproofing, maybe they could have multiple sets of heat shields that they rotate each launch and waterproof the ones not currently in use
Good video but I still don’t know how big and thick Starship tiles are and how that compares to the Shuttle. So related to that I don’t know what extra weight the TPS added to both vehicles. Be really interested to know. Everyday Astronaut asked Elon about it all it seemed to me at least that the non-tile transpiration cooling seems likely to be about the same weight-wise as the tiles, but the active system is far far more robust and rapidly reusable. So maybe it’ll change back in the medium term, or make the tile system absurdly robust, light, and inspection/maintenance free?
It's not the melting point of steel that matters, it's the temperature where it softens and loses it's structural strength - as in the temperature where blacksmiths would work it (if they could - it's a comparision, don't just all over me)
And you can buy it and use it as one of the best insulators. It’s called an aerogel, with a company that makes sub products, one called pyrogel and another called cryogel.
Greetings and thank you. I have a question about why the booster and the starship don’t float after landing in the ocean. It seems to me there could be a lot of data to be collected if you inspected it after landing.
@@TheEvilmooseofdoom even in water? wouldn’t the engine section, being the heaviest part sink straight down enough, that the water would cushions it as it falls the rest of the way?
@@pierredemontigny8154 Water doesn't help much, the problem is the pendulum effect. While the bottom doesn't move far, to go from being hundreds of feet up to flat on the ocean means the top (in a topple) is moving a LOT faster and thus hits a lot harder. Also should have mentioned that they depressurize the tanks right after landing and leave those valves open to let sea water in. I believe in all the F9 soft water landings only 1 didn't break up and sink.
Finally one of the YT commenters expresses skepticism about Starship's tiles and their potential to make Starship more expensive to reuse than touted. I'm disappointed that SpaceX dropped the original proposal which was for transpirational cooling. After all, one of the reasons put forward for the switch to stainless steel was that it would play well with transpirational cooling. I would have liked SpaceX to come up with a subscale Starship on which it could test novel thermal protection systems. A question for your Scott Manley. Have you ever seen anyone mention using a combination of carbon foams and coolant? So something like methane percolating through a carbon foam. As it progresses through the material, it first boils and then becomes a progressively hot gas. The neat thing about methane is that its heat capacity rises with temperature.
Having to refurbish the heat shield tiles after every shuttle flight just contradicts the concept of reusability in the space shuttle, it's like it was refurbishable not reusable!
So far every reusable rocket has needed non insignificant amounts of refurbishment after every flight, so yes, those terms are basically interchangeable. That EDA video has done a lot of damage to public perception of spaceflight (wouldn't be the first time either).
100%, I think people don’t understand how much more wear and tear something coming back from orbit like STS incurs compared to a Falcon 9 first stage; its gotten way too fashionable to bash on the Shuttle when Starship is going to have to lean massively on the mountains of TPS research and technology that wouldn’t exist without the trailblazing shuttle program.
7:05 I think if we solve manufacturing proces we can get better rezult with tile where instead of air flow around from hot side to cold side is buble roms independent of each other. How can be made? i was thinking in capilar tube technology from skylon/sabre but instead of using that tubes of stainless steel made with ceramic but must be thin, very thin walls because are the path of heat tranfer. when this solved the tube must be taped at X distance to avoid flow of air circulated from left to right on Z(depth) they already are isolated. And see how this work. this technology already aplied at bricks for themal gaps. If that dont work because tubes cant be so thin or the walls are to large. Can de solved with 3 layes sandwich each layers are made with this fibers glass the air flow will flow but only in the first room the hot room, the midle room aswell with fiber glass will be the thermal gap bettwen hot plasma and cryogenic. and tird one is the same in contact tih the cryogenic and the midle room sandwich. How make that sanwich? imagine already sheet fiberglass with lot of this capilars who ill be tangled when you pour the actul mix of fiber glas and water. So the inner, sperator of room dont touch directly the extreme surface.
The best way to mitigate this problem may simply be to have BIGGER spaceships. In re-entry, a shockwave forms at some distance from the surface that needs protection, and that shockwave is then isolated from that surface. Heat must radiate from the shockwave to the surface you want to protect. Am I correct in supposing that, for a larger surface, the shockwave forms at a larger distance? If so, then the wave sits at a greater distance from the surface you need to protect. And if it's far enough away, you may be able to dispense with things such as ablative layers that need a lot of rework between flights.
It's not the size, it's the curvature of the edges, that means wings and flaps are tricky to deal with. But that radiant heat from the shockwave is still a lot of heat to deal with, so you need a good heat shield even after getting the shockwave right.
A massive object will theoretically heat up faster over its surface due to the increased surface area facing against the atmosphere, meaning you have increased air resistance/drag. The air molecules would not just be more easily redirected like a highly aerodynamic shape, but instead be compressed and forced to move along the surface of the object till it reaches the edge. The shockwave propagates along the surface, until it reaches the end of the surface and begins to dissipate. Other surfaces beyond the main facing (effectively in the wake of the object) can be subject to heat via radiation off of the plasma that was generated under compression, but this is a far minor problem. I'm unsure what you mean by the shockwave in your comment - if you are taking about the plasma generated along the facing surface or the wake of the hot air/plasma. Normally the ablative heat shield elements for things like capsules do not need to be present anywhere but the facing surface.
@@V3RTIGO222 There's also the simple mass to surface area scaling. The mass, and hence kinetic energy to dissipate, grows faster than the surface area over which it's dissipated. Only way to square that circle is the plasma gets hotter.
@@QuantumHistorian True, but I would assume that you could also create a larger shield, using lighter material or through construction that allows the overall weight to remain similar or lighter, without changing the size of the vessel if you wanted to... I think the inflatable heat shields kind of use that concept to a limited degree. I will point out that with higher drag, you theoretically have a shorter period of time needed to slow the vessel, despite the higher peak temperature, which could be more advantageous.
@@V3RTIGO222 That would work if the timescale at which the temperature of the plasma is dangerously hot is shorter than the timescale for heat transfer. In this case, the main mechanism for heat transfer is radiative which is going to be pretty fast no matter what you do. So I think the craft (or, at least, the heat tiles) would really "feel" the peak temperature. There's a reason why starship uses aerodynamic lift to slow down it's descend and bleed off speed as slowly as possible. In addition, the thermal flux goes at T^4. And, roughly speaking, the integral of T over the whole of reentry is going to scale with the total kinetic energy loss, which goes up with mass. So if you halve the time of reentry, you double the temperature and so increase the heat flux by *16*. The scaling works against trying to get re-entry over and done with quickly.
maybe the engineers working on the Mercury, Gemini, Apollo project got it right. KISS. one can even use the high tech tiles developed since, but they should be replaced wholly after every landing. "one size fits all" just drives up the complexity and price of the process. one just has to think about the mechanical/thermal needs of each and every tile (one goes, so does the whole ship) slowing down from 28000 km/hr down to landing speed (zero?). the tiles still have a very good use, but for vessels designed to never set foot on a planet= they could be used to build very low mass, high internal volume spaceships. and the new generation of space stations, this time, they should look like the one in "2001". the tiles can actually be made in space, plenty of quartz and Al2O3 in the belt.
I had wondered why they're not using large ablative shield sections that could be rapidly replaced instead of a passive system. I guess the issues of not performing as well on a non blunt body vehicle, are likely prone to cracking, and fabrication is likely difficult are all showstoppers for such a protection system.
I have been saying for years that the heat shield tiles are going to be a huge problem for Starship. They might get them to work but it is going to put a huge damper on the reusability part. Elon has said many, many times that the end goal is to fly a Starship to orbit, bring it back, catch it with the tower, stack it back on a booster, refuel it, and immediately relaunch it. They will _never_ be able to do that using this thermal protection system. There will always be refurbishment needed before it flies again. So, they're going to have to figure something else out if they plan to turn around Starship like that.
So will you let us in to your source of all the confidential information on what they are doing? Or are you one of the armchair experts who 15 years ago said reusable rockets are never going to work?
@@TheEvilmooseofdoom And what exactly makes you think that? Do you guys really believe five years into the project the people at SpaceX went "Hum, what about water proofing by the way? Have we thought of that?"
I believe SpaceX focuses on possibility of "rapidly" attaching all tiles just before flight, that way the tiles can be factory prepared and kept in protective atmosphere like a consumable material.
Scott's last comment tells the correct reason for the rapid reuse problem for any Starship. He didn't, however, mention the cost of the tiles to be mfg'ed or refurbished once they return from space. That was always a high cost for any Shuttle. So with that in mind, how are they going to check the tiles once the craft is restacked? Seems that would hold up any other launches by creating a bottle neck. It may be better to allow Starship to reland on the ground and use a new ship for each flight. I'm sure they'll consider this if they can't resolve the tile problem. Just an opinion.....
Starship can reduce the cost of tile replacements a lot by its shape. Most of the tiles are the same size and shape, instead of each one being unique. The nose is rounded, but still more symmetrical than the space shuttle.
Stainless-steel is also a very bad heat conductor, so if you heat a very small spot, it may melt sooner than aluminium or copper, which can conduct away heat from a local hotspot.
The physics behind the performance of rigidized ceramic fiber tiles like the ones used on the Shuttle, the X-37, and Starship is called Mie Scattering. The selected fiber diameter (~1 micron) is "tuned" to the peak wavelength in the heat radiation inside the tile at the highest operating temperature (~2400F), called the Wien Peak, which is ~1 micron for blackbody radiation at 2400F. Those thin ceramic fibers strongly backscatter that heat radiation and effectively block it from penetrating deeply into the tile thickness. The very thin fibers are made of ultrahigh purity quartz and have very low thermal conductivity. For comparison, the diameter of a human hair is ~70 microns.
There are two parameters that characterize Mie Scattering, namely, the absorption coefficient and the backscattering coefficient. For the Shuttle tiles the backscattering coefficient is about 600 times larger than the absorption coefficient.
Side note: My lab spent almost three years (1969-71) developing and testing rigidized ceramic fiber tiles for the Shuttle. My job was to design and build the lab equipment to measure the absorption and backscattering coefficients of those developmental tiles.
What determines the ratio of absorption to backscattering coefficient? If I recall correctly, absorption and emission coefficients are the same at all wavelengths because of detailed balance and can be calculated (in theory, anyway) from molecular or electronic structure. But what's the physics that underlies the backscattering coefficient? Is it just geometry and the dielectric coefficient of the material? Or is there something more at play?
@@QuantumHistorian A dielectric fiber (quartz) with diameter matched to the predominant wavelength of the thermal radiation trying to penetrate the tile and having very low optical absorption (high transmission) in the 1 to 4 micron waveband (the near infrared region).
@@rays2506 Thanks, but that doesn't answer my actual question?
@@QuantumHistorian Mie Scattering.
@@QuantumHistorian Mie Scattering.
All @Scott Manley content is great, but these explanations of technical details of space flight are by far the best.
Yes, I remember watching another video about tiles and it was very technical. I Forgot who made it
I agree. And I imagine that anyone who worked on the development of the Space Shuttle heat shield who might watch this will feel a lot of gratitude.
Although we have very little to go on, it seems like SpaceX have chosen to walk the same path, looking for better solutions that modern technology may have made available, but will ultimately conclude that chemistry hasn't really moved forward, and the solutions worked out by NASA decades ago are still optimal.
All the Space Shuttle heat tile stuff went over my head. About 16 times per day, actually.
@@FLPhotoCatcher One day you will be held accountable for your dad jokes.
Right?! Absolute gold
Literally boiling a pot of water right now. I stared right at it, and can confirm my eyes are still ok
can you also touch it to test conductivity?
Pretty sure that’s cause a watched pot never boils
@@TastySlowCooker my induction stove laughs at that old tale 🤣 water boils in seconds.
Completely different story when I fallen asleep in front of the wood stove outside. As I’m snoozing it gradually works its way up to a nice, uniform orange color and I look like a lobster when I wake up.
@@Real28 that's one thing I miss about my old induction stove. That and it'd cool as fast as turning down a flame on a gas stove. Whereas my current gas stove sure as hell can't heat as quickly as an induction cooktop.
By the same token, I don't pay for gas in this apartment, it's included in the rent, but I sure do pay for electricity. So, I'll wait for the pot to heat up.
Dad may have raised a dummy, but he didn't raise no fool.
Our now retired material and manufacturing science teacher has a heat shield tile from the Buran shuttle. He always brought some interesting objects to show during his classes. The tiles are incredibly light, which makes sense since air/empty space is a very good insulator. The outer coating was black and very hard and quite brittle, the inside of the tile was white. Couldn't see what kind of a fiber structure it had though. The outer coat had some damage marks which looked like he had done some Brinell hardness tests on it, but I don't remember if he told us the results. But it sure seemed like it could be very glass-like hardness.
The story of acquiring that heat shield tile was quite simple. He went to the site where the Buran has been in storage for decades with some group, found the tile laying on the ground and just put it in his bag and hoped nobody would check the bags on his way home and across the border.
I own one of these Buran tiles as well, and they are really fascinating to handle. Even after handling it countless times over the years, when showing it to people etc, it still catches me off guard how light it is. It's like picking up a brick made of nothing. But at the same time, you can tell it is fragile - just by handling it carefully with just your fingers, there are little fragments that come off once in a while (like grain of sugar sized pieces, but still).
Excellent explanation Scott on how the "glass" tiles TPS works. Enough tech info to satisfy a nerd, but clear enough for a lay person to catch your drift.
Well, all of the TPS tiles have been silica based. The earliest, so delicate that one could, with a badly sprained hand, crush them easily by accident and were about as waterproof as the Titanic currently isn't. Later versions improved greatly on strength, which even now remains not much to write home about and waterproofing - which has improved tremendously.
Discussing the things, as Scott mentioned, ITAR can be a royal pain in the gonads, with prosecution being quite aggressive and the regulations being so nebulous in some areas as to literally leave it open enough that one could cite someone for an ITAR violation for discussing the chemical formula for pure water.
And given my military background initially involved intimate involvement in nuclear weapons, suffice it to say, we had a keen idea on ITAR regulations. That dated back to when even PGP encryption was considered a weapon.*
*Entertainingly, an allied foreign nation had ordained that encryption, especially VPN's were unlawful within their nation as they considered the technologies weapons. Citizens and residents were rather stuffed, but banks explained patiently that there were three chances that they'd engage in unencrypted financial transactions, slim chance, fat chance and no chance and that they'd cease doing business within said country.
Policies swiftly changed for some odd reason.
"I'm Scott Manley, fry safe".
Speaking about the sapphire strands, it's actually really easy to make your own sapphire. You take aluminum wool and mix a ball of it with aluminum oxide and put it in a container that can withstand the heat and put it in an old microwave for a minute or so. When you pull it out, you have clumps of sapphire mixed in with the powder. It's the same process for maming rubies in a microwave, but with rubies you add 1-2% chromium oxide to give them their color.
Wow, I can bake precious gems in a microwave?
I have to note that microwaving metal is generally not safe, and doing this in a non-ventilated area isn't a good idea.
Excellent and simple to understand. One correction: when you increase the thickness, it does simply "take longer" for the heat to get through, you double the thermal resistance, so you only get half the heat flux.
Hey Scott, Congress just passed something to expand VIPER’s budget, would be cool to see a video diving into that
That’s fantastic news!
We are so back
Got a source on that? I can't see any articles about it on Google
That was a very interesting look at heat tiles.. I never really looked at them this completely before.. thanks Scott.
Hey Scott, good video. Sort of a review for me. I have two friends from high school. Who worked in that shop that remade those tiles that were unusable. One has moved on to Blue origin. The other works for SpaceX tile manufacturing in Titusville, Florida. I think that's where they're at. But they expanded greatly when starship started up.
I think Mark was working 75 hours a week. Like I said before, good video. Thank you
That example of looking at a boiling pot of water and not burning your eyes (or face, hair, the surrounding skin, your shirt, the walls, the ceiling...) is a great example.
I immediately understood just useful it is in this case that radiation is less effective than conduction.
your videos are a must-watch for their clarity and depth! ️
4:16 I didn't realize @BreakingTaps removed that video.. Makes sense..
I really enjoyed this deep dive into heat shield technology! Thanks!
Another great video. I work in the facility you showed, and I program the CNC machines that cut the tiles. It's really cool seeing video of people I work with. I didn't realize this video was out there. As usual, you are spot on with the details of how thermal protection works.
Machining glass fibers, the most spicy of all the fibers!
Well there used to be a fibrous material of choice that was even spicy-hotter. Called asbestos.
Yeah that made me wince
@@etcher6841 FWIW PCBs are also made of glass fiber and machining them is a mature and dirt cheap process
The forbidden pasta.
@@General12th The forbidden Wheaties.
Oh Scott, you had me at "metallurgical changes" and "microstructure!!!" Great video!
Great video Scott, thanks for all your research and effort putting this together.
I like that you make the same video for the professional physicist and the weekend fan alike. Love the content, keep it up!
if anyone is wondering how different spacex tiles are from space shuttle , the only difference is that there are fibers of different cross sections in the mix and some small granules of various elements embedded into fibers
Also the black coating flows more into material
Hackaday still has a picture from the video up of a Starship tile structure. I would presume the larger, denser fibers dispersed through the media are a compromise between strength, heat protection, and weight.
Also, they are much, much more substantial. Look how thick they are and with a mechanical fixing rather than the shuttle ones which break if you look at them, held on by glue.
@@mysock351C In general when one includes larger fibres in a matrix it's to improve the tensile strength of the material and limit cracking. A mix of different diametre fibres can also get you to a lower density for a given strength than a constant density. So it's not particularly surprising.
@@Shrouded_reaper The one advantage that Starship has is that does a belly-flop back into the atmosphere. One of the things that arguably doomed the shuttle was the requirement that it be able to fly (more aptly glide poory) back all the way to the surface. It couldn’t afford much extra weight, and the shuttle tiles are quite light. Starship on the other hand is more brute-force, so they are likely able to accept the added weight and reduced thermal performance that comes with having a mixture of fiber diameters in the mix for reinforcement. It can just come back more or less ballistically to the landing site once it’s slowed down enough.
@@mysock351C
IfUSāSō
ITAR is no joke. Glad you checked.
Wonder if a plumber's soldering blanket could help? ~2,300 degrees and cheaper than dirt. 17cents a square inch retail.
But probably ultra heavy. Everything is a trade-off
Does this mean a different density tile for Mars? 'air' spacing..😮
ITAR can be odd. A microscopic pic might get you in trouble? Yet the tiles themselves are available on eBay. I'm sure the Chinese bought some early on and have studied them under their finest microscopes. IIRC after OFT-1 some were gathered from the beach and hadn't been in the ocean.
There are space rated similar blankets, but I don't think they temp range is quite high enough. Much of the white 'tiles' on the shuttle were FRSI (Felt Reusable Surface Insulation) that look like a quilted blanket. If something similar could be developed in a high enough temperature range, it would remove the problem of the fragile tiles.
The heat isn't particularly hard to deal with on its own. The main problem is that plasma at those velocities can strip out individual atoms and molecules, so the surface material has to be extremely chemically stable at an extreme range of temperatures while also being strong and rigid enough to protect the insulating layer.
Very informative, answering questions i have long had about these heat tiles !
Thank you,
You're one of my favorite teachers
I remember going to the kennedy space center and midway thru the tour i seen an example of how a heat tile works ! It was heated red hot and tossed at me ! I caught it and it was cool to the touch and i got to keep it ! Then my sister stole from me when we got home !
No you didn't. That never happened
@@penguin44ca No one has had n interesting experience according to you?
@@penguin44ca I found a video of this demonstration at KSC on youtube. Search for "Space Shuttle Thermal Tile Demonstration". They encouraged people to come up and pickup the glowing hot tiles. What the OP described is not a stretch. Sounds believable to me.
@@penguin44ca That may not be on the public tour, but he may have been someone's kid and gotten a VIP tour. Based on his grammar, it was probably a senator.
@penguin44ca theres clips on TH-cam if this demonstration being done. I couldn't tell you if this particular person went to it though
The heatshield is why the spaceshuttle never got rapidly reusable as they had hoped. It simply took to much time to refurbish it.
But with Starship they have proven that they can replace the heatshield in litteraly no time so I imagine that alone will make a difference.
Thank you for sharing these TPS reports with us.
I watched that video about the heat tile comparison. I didn't realize he took down the video though.
Yeah ITAR is no joke. You do NOT want to be on that naughty list.
But you'd think it wouldn't be an issue since these bits of tiles are literally everywhere at this point
@@JohnVanderbeckbut it is a joke.
"No foreign bad actors know about this because we said they are not allowed to know about it"
They know. It'd be very naive to think otherwise.
@@georgeprout42 Knowing and building are two different things.
@@georgeprout42 Let me rephrase. The government does not treat ITAR like a joke. They will come after your a...
NASA recently announced the development of a new lightweight alloy with enhanced properties meant to withstand extreme conditions including heat and cold. Referred to as GRX-810, NASA has already selected several companies to produce and market use of the product. From what I could see of the tiles, they have a thin metal "plate" inside each tile that clips to prongs welded to the Starship. I'm convinced that use of this new alloy or something like it will resolve the problem. I don't think making the rocket out of the metal alone will fix the problem but a tile, with or without underlayment, might work. The ceramic itself break apart under certain conditions and cannot be relied on to do the job. What SX has done so far is provide a short term solution to get the Starship airborne and home again. NASA may already have a solution in hand.
There was also the metallic TPS that was planned for the VentureStar.
Absolutely fascinating! Thank you for the top notch content, as always🙏
so in reality i dont mess up the settings for my 3D printer, i just accidentally built a TPS
You would, had it printed with 1-micron fiber.
@@artemkras He clearly tuned his TPS for a longer wavelength radiation.
@@artemkras heh, 1 micron filament would be a nice resolution! No clue how to implement such a resolution though, largely due to wavelength...
Don't forget the new cover sheets. I'll resend you that memo.
Great video as always Scott 🙏💯
I'm glad I saw that video before it was taken down
Excellent video. Thanks for this analysis! Super interesting content!
Excellent breakdown of this fascinating invention.
Once again, a great episode!
Very good video. The only thing that is radiation heat transfer is not about the temperature, it is about the temperature differences so as the tile heats up, the radiation heat transfer slows down
Back when the Space Shuttle was flying I recall seeing a research paper about using multi layer corregated titanium instead of the silicon tiles. Supposedly it would be more resistent to wear and tear. Anyone know what happened to it? Was it less resistent? Did it cost more?
Titanium loses strength and oxidation resistance at temperatures above 500C. The Shuttle tiles have to survive temperatures up to 1300C.
Highly underrated, ridiculously informative, and downright entertaining. This is one of my fav channels on YT and I wanna thank you so much for sharing Scott! 🫡
Yes, I think you are right about heat shielding being the main problem for making Starship rapidly re-usable. The Space-shuttle was intended to be rapidly re-usable - but it never happened!
Booster needs to be rapidly reusable. Ships? Not so much. You have 10 ships in rotation running on 2 or 3 boosters. (tankers for fuel to LEO, primarily). Crewed starships will be a tiny fraction of ships launched. The same folks who believe the same starship combo (ship and booster) will fly the same day are the same folks that believe that starship point to point will actually happen. The vast majority of starships to mars, for example, will not be coming back. Folks don't understand how the program will operate.
@@KnugLidi the main factor will be cost. If it takes too long or too much working hours it becomes to expensive. So the ships in fact need to be rapidly reusable. We can argue about what is "rapid", but it definitly is the critical factor.
@@teshtrion7860 Consider the use cases. Ship to LEO for cargo deploy - cargo loading and integration will limit reuse. Ship to LEO crewed - tiny percentage of usage, if any in short term and not high operation rate. Ship beyond LEO - that ship likely single use. Lunar cargo will be rare and likely would be single or limited to leo-luna-leo runs. Fuel to LEO - this is the case with the likely highest need for reusability, but this only applies for flights beyond LEO which are going to be the exception rather than the rule. Starlink to orbit, second highest use case in medium term, several flights a week, but not necessarily on same ship. As for Mars, due to the limited windows - long periods with no flights and a flurry every window - will be limited due to the lack of paid missions and will be 4-5 windows before the idea of launching a squadron of ships in the same window.
Its very obvious how delicate and soft the material is from the clip at 7:20 showing the worker removing the silicon 'sponge' from the furnace as you say "to give it some strength" you can see an impression from the hand of the guy who picked it up, its that soft.
Thank you for reminding us all that NASA and SpaceX have worked together to use materials science advancements that occurred as a consequence of the experience gained during the decades-long Space Shuttle program. As always, you stand head-and-shoulders above most of your peers because of technical deep dives such as the one we had the pleasure of receiving in this video.
Very interesting, thanks Scott!
Another episode on how they're attached would be fun, as it's super interesting! If memory serves, the Space Shuttle had Inconel pins embedded in them and then an Inconel fixture on the aluminium frame, so even the fitting was a high temperature and high thermal resistance piece!
I got to handle one of those tiles once. It was shockingly light. If you waved it up and down you'd feel the air resistance more than the weight.
"Heat will pass by - conduction! Heat will pass by - convection! Heat will pass by - radiation! And that's a physical law!" - Flanders and Swann
'You can't move heat from a cooler to a hotter'!
How is this different from asbestos insulation? I thought the reason asbestos was so dangerous was because of how small its particles were. Wouldn't flying ships covered in this stuff cause respiratory issues?
I think you make informative videos and I’m a real person.
For those wondering why ITAR wouldn't want information disclosed about heat shields, its because passive heat shields are essential for accurate ICBM reentry vehicles. If you use ablative heat shields on the warheads, accuracy will reduce.
If ITAR was important here, NASA wouldn't have published all those details about the Space Shuttle TPS.
All modern reentry vehicles used by the US have ablative heat shields. They ensure accuracy by spinning the reentry vehicles to prevent uneven ablation effecting accuracy, plus in the Trident D5's Mk.5 reentry body they have metal filaments running along the axis of symmetry to make ablation more predictable.
Do you know anything about the heatshield that the X-33 was going to use? I found a picture from the air and space museum, presumably the back side of the tile (can find it searching for this -> NASM-A20060281000_PS03). It was developed by BF Goodrich (tire company?) and used Inconel. I'm not aware of that design finding its way onto any other vehicle.
Im not surprised that idea died. Inconel is very heavy.
I spent time during 1995-96 developing and measuring the insulating properties of a half dozen heat shield concepts for NASA's X-33 under contract to NASA. That Goodrich Inconel thermal insulation panel was one of those concepts. Inconel has a maximum use temperature around 1800F. The maximum temperature on the Space Shuttle tiles was ~2400F. So, those Inconel tiles are a lot heavier than the Shuttle tiles and don't have enough high temperature capability.
Lockheed was convinced that its Venture Star X-33 vehicle could fly entry trajectories that kept the peak temperature below 1800F. We will never know if that vehicle could have performed that feat because NASA canceled that over budget and behind schedule program before any test flights were attempted.
Metallic thermal protection systems based on superalloys, like the one planned for VentureStar, seem understudied. There are a few papers available online by Blosser et al.
I fully agree with you … the TPS has to be the biggest challenge.
Thinking back … although shuttle used ceramic tiles for the major extent of airframe protection, didn’t they use reinforced carbon-carbon panels for wing leading edges …ie; those parts which needed thermal protection but where the local loading environment was more aggressive than the ceramic tiles could withstand??
Yes … I am thinking about the same parts that proved vulnerable to impact damage from chunks of closed cell foam being shed from the main external tank. However, I assume this material could be manufactured in appropriate geometries that could offer good thermal protection to those parts of Starship (flaps) that proved challenging based on FT4.
Sadly, I am not sure about the thermal properties/performance of this material and I suspect it comes with a weight penalty … but it might offer a potential compromise solution?? I believe RCC composites are good to >2000C with breakdown by sublimation at >3500C.
I have also wondered if exposed parts of Starship airframe could be fabricated from inconel alloys to provide for superior integrity in exposed locations such that they might still perform adequately with reduced thermal protection.
Maybe a combination of localised use of Inconel structure with RCC cladding??
Has anyone looked at the potential of a hybrid panel of ceramic matrix core laminated into an RCC structure? … similar to a typical honeycomb panel? … though probably find the matrix would be crushed in the lamination process ☹️.
Just some wild thoughts and speculation from a retired aerospace engineer ….
One minor correction: alumina (Al2O3) is only called sapphire in a specific crystalline form (the alpha phase). I'm pretty sure this would be amorphous alumina, which is definitely not sapphire.
Other than that, great and interesting video!!
Actually given the temperature stability of TUFROC / similar materials, it likely is polycrystalline already (due to the heat treatment)
Thanks Scott and you fly safe my friend.....
Old F-4 Phantom ll jet fighter pilot Shoe🇺🇸
Thermodynamicists hate it when you do this, but they can't stop you!
Fascinating! Thanks Scott.
A watched pot never boils, your eyes.
Thanks Scott.
I wonder how different SpaceX and Sierra Space's tiles are given they both used the space shuttle data to design them
Space shuttle data?
@TheEvilmooseofdoom both companies cooperated with NASA in their designs. I'm assuming they looked at some engineering info we don't get to
@@Shadare I know spacex worked with NASA on the pica-x heat shield but not Starship. Since each TPS is unique to each vehicle I'm not sure how much data from the shuttle program would have been useful but perhaps some.
@TheEvilmooseofdoom Not starting from scratch designing the manufacturing methods is more what I mean. It would have taken a lot of time and money to re do all that engineering and I doubt that all 3 would share such stark similarities if they were designed by completely separate engineers not cooperating at all. NASA wants to see these vehicles succeed. They aren't greedily sitting on their patents waiting for everyone to fail. I think it's a little weird how resistant people are to what seems like such an obvious explanation.
I once saw a video of someone in the facility making those Spaceshuttle tiles pulling one of the tiles, glowing white hot, out of an oven using a pair of tonges. And then just picked it up with their hands without getting burned
Yup... about 10 seconds after the tech removed it, the tech was able to pick it up by the corners using his finger tips.
Thanks, that was super interesting and informative.
9:27 HE SAID THE THING
Were you able to reference the since deleted breaking taps video for this? Very useful
If there's any loose tiles from Starship's re-entry, it'll be found on beaches between Perth and Broome.
The bigger question will be, can Starships re-entry be seen from there? The current flight plan should have it visible from Diego Garcia and the cargo and fishing vessels that cross the Indian Ocean, plus maybe one other island group.
I feel like there must be an even better way to make heat shielding that we haven't discovered yet, some kind of materials science using crystals? We love crystals right?
Doesn't a ceramic heat shield slowly dissipate its absorbed heat over time? I think I remember that Shuttle needed heavy venting for hours after each re-entry so the orbiter wouldn't get too hot inside after landing.
I wonder how this might impact Starship's plans for rapid reuse.
It doesn't let much heat through, and reflects as much as possible, but yes, all the heat it absorbs will come out at some point. You do get to take advantage of convection to cool while you're on the ground, though.
Gunna be actively cooled eventually
I guess the inflatable heat shield that NASA tested for ULA to recover their engines (eventually) uses a material more flexible than ceramics.
Ceramic fibers can actually be surprisingly flexible depending on the chemical composition and production method. The TPS tiles shown in the video are specifically made to be rigid through extreme compression and heat/chemical treatment. You can also combine ceramic fibers with heat resistant polymers like Kevlar to make composite textiles
Is there a spray on ablative ceramic coating that could be applied to outside of the existing Starship ceramic tiles that could be reapplied between flights?
Another banger, sir
I've been looking forward to you doing a video like this. Space X's approach for this up-coming test flight looks like a sticking plaster, literally, when you consider they're using a layered technique of ablative and non-ablative materials. Hardly an easy process to replace quickly between flights! But that always learn a lot with their fast experimental approach. We'll see!
The goal is not to replace them between flights.
@@TheEvilmooseofdoom yes, it sure is. But you can't reuse an ablative layer if if ablates. If the other tiles stay put, all well and good. It's just a stretch to imagine that the under-layer will not be affected. We'll be see. I hope I'm wrong!
The shuttle was really cool.
It was a flex.
But to be economic start with booster reuse, not orbiter, like falcon 9.
@@xehpuk I thought it did serve purposes other than “flexing” for the US? Like payload and crew rotation on the iss/mir. Also, the boosters were reused, the main orange tank fell into the ocean. The boosters fell back to earth with parachutes which allows them to survive.
@@interestinggameraltlol9245I would hardly call the boosters "reused". They were basically building them from scratch every time.
What was that stuff called that some guy claimed to have invented? Starlite? It could withstand high temperatures on one side whhile staying cool on the other.
I believe that Starlite falls into the category of ablative shielding compounds, as the outer layer would char, protecting the what's underneath from excessive heat.
2:00
most alloys loose most of hteir strenght at around half its melting point
Respect for the stylish aerobraking of SpaceX that kept spacecraft at 56km altitude, and bleed of thousands of m/s without loosing height.
I think the high temperature capability of stainless steel may not amount to much payload benefit for Starship in the end. Having very hot interior surfaces isn’t really acceptable for your payload, especially the human type, and generally a bad idea around LOX. It is more robust than aluminum, but apparently neither the Shuttle or Starship was “robust to loss of a single tile” - hence the ablative layer. It will be interesting to see how the two typical heatshield sections finally compare on lb/ft2. Presumably Starship will eventually be more reliable than the Shuttle, but perhaps not much lighter.
Starship did lose a bunch of tiles and some flaps yet it still landed safely
They were robust enough, it's just not enough of a safety margin. Starship is still in development, the TPS is, like everything else involved, a WIP.
@@linecraftman3907 Yes, that may have been lucky though. Elon said "not robust to loss of a tile" I believe, so maybe if tile loss occurred somewhere else it would have been more serious - e.g. payload pay, LOX tank, ??? In the end they have elected to add the ablative layers to improve reliability, but this also adds weight. Provided none of the heatshield fails the steel temperature may never be much higher than the Shuttle aluminum temperature (and so about the same weight) - it will just be rapidly reuseable and more reliable.
@@marksinclair701 that interview was pre-flight
iirc, in the post flight it became known that the steel iviewed from inside was glowing hot, so tiles were lost - ship was ok
@@linecraftman3907 I think you're right, but I don't think that changes the outcome. They decided to add the ablative anyway, and pay that mass penalty. Red hot interior steel might be acceptable in the skirt or an empty payload bay, but I doubt its OK in an occupied payload bay or a LOX tank.
Do you know where the tiles were lost or are these the ones they removed?
The new thumbnail is better 👍
If replacing the heatshield is faster than re-waterproofing, maybe they could have multiple sets of heat shields that they rotate each launch and waterproof the ones not currently in use
7:26 if the black layer is impermeable... how did they address the trapped air pressure when the tiles rose into a vacuum environment?
Good video but I still don’t know how big and thick Starship tiles are and how that compares to the Shuttle. So related to that I don’t know what extra weight the TPS added to both vehicles. Be really interested to know. Everyday Astronaut asked Elon about it all it seemed to me at least that the non-tile transpiration cooling seems likely to be about the same weight-wise as the tiles, but the active system is far far more robust and rapidly reusable. So maybe it’ll change back in the medium term, or make the tile system absurdly robust, light, and inspection/maintenance free?
It's not the melting point of steel that matters, it's the temperature where it softens and loses it's structural strength - as in the temperature where blacksmiths would work it (if they could - it's a comparision, don't just all over me)
Could some sort of aerogel coating possibly be the solution to this? I know it’s both very hydrophobic and also very good at thermal insulation
It doesn't stand up mechanically though. Otherwise it would be good.
..or a combination of both : aerogel soaked fibers carefully dehydrated afterwards?
Yes, aerogel is incredibly weak. It would be shredded by the time the rocket reaches max-Q.
And you can buy it and use it as one of the best insulators. It’s called an aerogel, with a company that makes sub products, one called pyrogel and another called cryogel.
Aerogel has some issues in space flight that make it a less than ideal choice for this.
Greetings and thank you. I have a question about why the booster and the starship don’t float after landing in the ocean. It seems to me there could be a lot of data to be collected if you inspected it after landing.
Because giant things 10+ stories tall toppling over rarely land intact.
@@TheEvilmooseofdoom even in water? wouldn’t the engine section, being the heaviest part sink straight down enough, that the water would cushions it as it falls the rest of the way?
@@pierredemontigny8154 Water doesn't help much, the problem is the pendulum effect. While the bottom doesn't move far, to go from being hundreds of feet up to flat on the ocean means the top (in a topple) is moving a LOT faster and thus hits a lot harder. Also should have mentioned that they depressurize the tanks right after landing and leave those valves open to let sea water in. I believe in all the F9 soft water landings only 1 didn't break up and sink.
Right on Scott Manley. I've been following you since the Eve Online players shared your name by word of mouth. It must be a decade or more. +++
I concur scott
Finally one of the YT commenters expresses skepticism about Starship's tiles and their potential to make Starship more expensive to reuse than touted.
I'm disappointed that SpaceX dropped the original proposal which was for transpirational cooling. After all, one of the reasons put forward for the switch to stainless steel was that it would play well with transpirational cooling. I would have liked SpaceX to come up with a subscale Starship on which it could test novel thermal protection systems.
A question for your Scott Manley. Have you ever seen anyone mention using a combination of carbon foams and coolant? So something like methane percolating through a carbon foam. As it progresses through the material, it first boils and then becomes a progressively hot gas. The neat thing about methane is that its heat capacity rises with temperature.
Having to refurbish the heat shield tiles after every shuttle flight just contradicts the concept of reusability in the space shuttle, it's like it was refurbishable not reusable!
Yeah, those two words were almost used interchangeably despite the very different meaning.
@@TheEvilmooseofdoom Oh yeah I remember. I think Tim Dodd has a video on this too!
If we wanted true reusability we would have to have powered landings to Earth's surface. Very expensive.
So far every reusable rocket has needed non insignificant amounts of refurbishment after every flight, so yes, those terms are basically interchangeable.
That EDA video has done a lot of damage to public perception of spaceflight (wouldn't be the first time either).
100%, I think people don’t understand how much more wear and tear something coming back from orbit like STS incurs compared to a Falcon 9 first stage; its gotten way too fashionable to bash on the Shuttle when Starship is going to have to lean massively on the mountains of TPS research and technology that wouldn’t exist without the trailblazing shuttle program.
7:05 I think if we solve manufacturing proces we can get better rezult with tile where instead of air flow around from hot side to cold side is buble roms independent of each other.
How can be made? i was thinking in capilar tube technology from skylon/sabre but instead of using that tubes of stainless steel made with ceramic but must be thin, very thin walls because are the path of heat tranfer. when this solved the tube must be taped at X distance to avoid flow of air circulated from left to right on Z(depth) they already are isolated. And see how this work. this technology already aplied at bricks for themal gaps.
If that dont work because tubes cant be so thin or the walls are to large. Can de solved with 3 layes sandwich each layers are made with this fibers glass the air flow will flow but only in the first room the hot room, the midle room aswell with fiber glass will be the thermal gap bettwen hot plasma and cryogenic. and tird one is the same in contact tih the cryogenic and the midle room sandwich. How make that sanwich? imagine already sheet fiberglass with lot of this capilars who ill be tangled when you pour the actul mix of fiber glas and water. So the inner, sperator of room dont touch directly the extreme surface.
The best way to mitigate this problem may simply be to have BIGGER spaceships. In re-entry, a shockwave forms at some distance from the surface that needs protection, and that shockwave is then isolated from that surface. Heat must radiate from the shockwave to the surface you want to protect. Am I correct in supposing that, for a larger surface, the shockwave forms at a larger distance? If so, then the wave sits at a greater distance from the surface you need to protect. And if it's far enough away, you may be able to dispense with things such as ablative layers that need a lot of rework between flights.
It's not the size, it's the curvature of the edges, that means wings and flaps are tricky to deal with. But that radiant heat from the shockwave is still a lot of heat to deal with, so you need a good heat shield even after getting the shockwave right.
A massive object will theoretically heat up faster over its surface due to the increased surface area facing against the atmosphere, meaning you have increased air resistance/drag. The air molecules would not just be more easily redirected like a highly aerodynamic shape, but instead be compressed and forced to move along the surface of the object till it reaches the edge.
The shockwave propagates along the surface, until it reaches the end of the surface and begins to dissipate. Other surfaces beyond the main facing (effectively in the wake of the object) can be subject to heat via radiation off of the plasma that was generated under compression, but this is a far minor problem.
I'm unsure what you mean by the shockwave in your comment - if you are taking about the plasma generated along the facing surface or the wake of the hot air/plasma. Normally the ablative heat shield elements for things like capsules do not need to be present anywhere but the facing surface.
@@V3RTIGO222 There's also the simple mass to surface area scaling. The mass, and hence kinetic energy to dissipate, grows faster than the surface area over which it's dissipated. Only way to square that circle is the plasma gets hotter.
@@QuantumHistorian True, but I would assume that you could also create a larger shield, using lighter material or through construction that allows the overall weight to remain similar or lighter, without changing the size of the vessel if you wanted to... I think the inflatable heat shields kind of use that concept to a limited degree.
I will point out that with higher drag, you theoretically have a shorter period of time needed to slow the vessel, despite the higher peak temperature, which could be more advantageous.
@@V3RTIGO222 That would work if the timescale at which the temperature of the plasma is dangerously hot is shorter than the timescale for heat transfer. In this case, the main mechanism for heat transfer is radiative which is going to be pretty fast no matter what you do. So I think the craft (or, at least, the heat tiles) would really "feel" the peak temperature. There's a reason why starship uses aerodynamic lift to slow down it's descend and bleed off speed as slowly as possible.
In addition, the thermal flux goes at T^4. And, roughly speaking, the integral of T over the whole of reentry is going to scale with the total kinetic energy loss, which goes up with mass. So if you halve the time of reentry, you double the temperature and so increase the heat flux by *16*. The scaling works against trying to get re-entry over and done with quickly.
Thank you. Very helpful.
maybe the engineers working on the Mercury, Gemini, Apollo project got it right. KISS. one can even use the high tech tiles developed since, but they should be replaced wholly after every landing. "one size fits all" just drives up the complexity and price of the process. one just has to think about the mechanical/thermal needs of each and every tile (one goes, so does the whole ship) slowing down from 28000 km/hr down to landing speed (zero?). the tiles still have a very good use, but for vessels designed to never set foot on a planet= they could be used to build very low mass, high internal volume spaceships. and the new generation of space stations, this time, they should look like the one in "2001". the tiles can actually be made in space, plenty of quartz and Al2O3 in the belt.
I had wondered why they're not using large ablative shield sections that could be rapidly replaced instead of a passive system. I guess the issues of not performing as well on a non blunt body vehicle, are likely prone to cracking, and fabrication is likely difficult are all showstoppers for such a protection system.
It's not so easy to make large ceramic heat shield parts.
Ablative heat shields are heavy, not reusable and as they ablate they change the shape of the surface.
Experiments with adiabatic (no radiator needed) engines use alumina parts and shields in heat facing parts. It’s amazing stuff.
Excellent, 👍
So after everything, they've fallen in to the same trap as the space shuttle. Heat shield tiles and tile maintenance.
No, they are doing things a little different, but a TPS is a must no matter what.
We'll see if the implementation is better this time.
I have been saying for years that the heat shield tiles are going to be a huge problem for Starship. They might get them to work but it is going to put a huge damper on the reusability part. Elon has said many, many times that the end goal is to fly a Starship to orbit, bring it back, catch it with the tower, stack it back on a booster, refuel it, and immediately relaunch it. They will _never_ be able to do that using this thermal protection system. There will always be refurbishment needed before it flies again. So, they're going to have to figure something else out if they plan to turn around Starship like that.
So will you let us in to your source of all the confidential information on what they are doing? Or are you one of the armchair experts who 15 years ago said reusable rockets are never going to work?
@@christiannorf1680 Armchair expert.
@@TheEvilmooseofdoom And what exactly makes you think that? Do you guys really believe five years into the project the people at SpaceX went "Hum, what about water proofing by the way? Have we thought of that?"
4:03 that's a bigass microscope image lmao
I believe SpaceX focuses on possibility of "rapidly" attaching all tiles just before flight, that way the tiles can be factory prepared and kept in protective atmosphere like a consumable material.
Currently removing tiles from starship requires breaking the tile.
That sounds like it would take some time no matter how fast you get the process
Did the Buran ever fly?
Yes, Buran flew very often to test its aerodynamics. It also once went into orbit.
Scott's last comment tells the correct reason for the rapid reuse problem for any Starship. He didn't, however, mention the cost of the tiles to be mfg'ed or refurbished once they return from space. That was always a high cost for any Shuttle. So with that in mind, how are they going to check the tiles once the craft is restacked? Seems that would hold up any other launches by creating a bottle neck. It may be better to allow Starship to reland on the ground and use a new ship for each flight. I'm sure they'll consider this if they can't resolve the tile problem. Just an opinion.....
I don’t doubt that the first ship to be recovered will be examined in great detail.
Starship can reduce the cost of tile replacements a lot by its shape. Most of the tiles are the same size and shape, instead of each one being unique. The nose is rounded, but still more symmetrical than the space shuttle.
@@Br3ttM Indeed. They are also easier to replace, and fall off more easily.
Stainless-steel is also a very bad heat conductor, so if you heat a very small spot, it may melt sooner than aluminium or copper, which can conduct away heat from a local hotspot.
Thats actually a good thing.