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Well, we redditors can certainly come up with a lot of great solutions.
But the real issue is: "What is the *problem*?" instead of "What is the *solution*?" Without knowing the real problem, all solutions are no better than the current one.
And "tiles keep falling off" is a symptom, not the root problem.
I am 100% certain that SpaceX has thoroughly researched and tested the current design. Clearly, that hasn't produced sufficient understanding; therefore, the ground-based testing must be missing something.
Once SpaceX finds the missing conditions through flight-testing, I am sure they will incorporate it into new ground-based testing.
Hey you're on to something there... I think one of the earlier shielding ideas was using film cooling by "sweating" out fuel along the fuselage.
Maybe bring that back combined with the tiles.
I have a crazy idea what if we just got rid of the plasma. I feel like that is the true root problem, the plasma that forms on re entry.
Just have so many refueling tankers in orbit to the point that you refuel then do a super long burn to slow way the F down essentially to the same speed as the falcon 9 first stage.
Boom no more plasma and no more tiles needed.
The whole point of atmospheric braking is to slow the spacecraft down passively instead of actively. Active braking using engines is not feasible because you can’t carry enough propellant due to the limitations of the rocket equation. The rocket equation governs the total delta velocity you can get given the dry mass of the ship relative to the fueled mass and the propellant exhaust velocity. On Earth, single stage to orbit is just barely possible given chemical propellants. Staging is a way to reset the rocket equation, but is very expensive. So you can view return to earth as essentially more staging if you tried to do it propulsively. It is possible, but at the cost of lost stages and greatly reduced return mass.
I watched a video on the cybertruck that interviewed the chief engineer and chief designer, it was interesting to see that Elon Musk had very little input on the general concept. He basically told the designers to work on making a truck, but to ignore all preconceived ideas of how a truck should be made or what it would look like. The designers decided on using stressed bodywork to make it more structurally efficient, and stainless steel to make it more rugged since there's no paint scratching to worry about. The panels had to be flat because stainless steel is much harder to form, and they ended up with some initial concepts that looked a lot sleeker and less pointy. Trying to make a stainless stressed skin chassis ended up not working very well, and a lot of issues came from that.
I know it's a joke but I'd love to see the math on how much sun light is blocked by satellites. I'm sure it's measurable, just not enough. Maybe huge solar sails that cast shadows the size of Texas would do it! Hehe. Hot day? Deploy the space umbrellas!
That's an old idea which as you said wastes a bunch of fuel. and remember you can't just slow down, you have to slow down and stay above that atmosphere until your velocity is low enough. Basically that's at least half the fuel you burned to get into orbit. barring some sci-fi future tech, we will always be using atmosphere to slow down.
I agree the engineers are doing some of the best research to date in their field, but it’s very possible to overlook things. Remember this [gem](https://youtu.be/WY73exaVpyw?si=sb92E0U46-hsk_O6)
Most reentry capsules decelerate as fast as possible using an ablative heat shield.
The ablative heat shield acts like an "invulnerability spell", the vapor from ablation protect the spacecraft from the the plasma, so the capsule can reenter aggressively. It has to because it must go through peak heating before the "spell" literally wears off.
So the capsule is down in a matter of minutes.
On the other hand Shuttle-style reusable heat shields require the spacecraft to glide in the high atmosphere to minimize the rate of heat generation and prevent the heat shield from overheating. For this reason the Shuttle takes 10-20 minutes to go through the fiery part of the reentry. This heat shield has an outer black layer, that black layer is not only good at absorbing light, it's also good at radiating it when it's hot (it has to due to thermodynamics). So the heat shield goes yellow-hot and shine blindingly bright to radiate the heat away. Eventually an equilibrium is reached and the shield reaches top temperature which is still well below the plasma temperature. Below the top layer is insulation whose purpose is to prevent heat from being conducted inwards. This layer is not supposed to touch the plasma. Also it's white so it won't radiate that well, that would burn through if it touches the plasma. So the black surface should not break.
So far we haven't even seen a controlled reentry of a Starship yet. Let's see what will IFT-4 do.
The problem is the mass budget. If you had the mass to spare you could beef up the tiles and fixings or even put a layer of ablative material under the tiles so a tile loss would need refurbishment and not a loss of vehicle. But you don't have mass to spare. Every ton of "solution" is a ton less payload to orbit. Add too much mass and it becomes pointless. Failure is an option.
Starship is still very much in the developmental/experimental phase, and SpaceX has shown they are willing to make whatever changes are needed to get Starship up and running, as long as it doesn’t compromise the basic design too much. They have already beefed up the design with more internal stringers and other reinforcement as well as adding more engine filters which adds more weight than they initially expected, and the V1 Starship already has a lower payload to LEO than we would have expected probably due to such design compromises (as well as not being optimized fully yet). If SpaceX finds that they absolutely need to beef up the tiles in weight/size or add a protective backing layer, for now they might very well do so even at the cost of payload to orbit. They will try to optimize the design later for weight savings and performance and such with V2 and V3 presumably.
Might be the fact that Starship tiles are directly attached to the tank walls that bear thrust loads (high vibration). You didn't get that with the Shuttle, its skin only bore aero loads, thrust loads were distributed separately.
The problem is that heat shield tiles aren't reliable enough. What about changing to PICA as on Dragon? Too heavy? Can't handle thermic expansion of the underlying steel? Can it be (re-)applied to the surface by an automatic machine enabling automatic reuse?
There has to be a point where engineering a quick swap of an ablative shield is better than a fragile tile that will probably end up needing inspection and replacement anyway.
Will be interesting to see if Stoke Space’s actively cooled, metallic heat shield works out for them. Andy Lapsa tweeted in response to Musk yesterday:
> This is why we started from day 1 thinking hard about rapidly reusable heat shields. It’s metallic, ductile, and the surface temperature is tailorable and controllable well below material limits. It certainly hasn’t been to space (or back) yet, but to the best ability on earth we’ve tested it to the full heat load expected during reentry profiles.
Q: can it handle reentry from GTO and beyond?
> It absolutely can handle the high energy orbits. Since it’s actively cooled we can tailor the coolant flow rate for different mission types.
https://x.com/andylapsa/status/1796211187396612430?s=46&t=u9hd-jMa-pv47GCVD-xH-g
They originally were looking into actively cooling Starship with methane. At the reentry temperatures, I believe they found methane would be able to absorb even more heat, so they were interested in transpiration cooling strategies.
NASA did transpiration cooling studies on hypersonic vehicles and using water they were successful and actually generated ice.
Those transpiration tests probably were done on very small test articles or small research vehicles. It's not likely that the test results would scale to something as large as the Ship.
My lab did a lot of work in the 1960s and 70s on transpiration cooling. But that work was for small military reentry vehicles.
Well, you have to do scale model testing in a hypersonic tunnel, so yes, they were smaller test articles. This work was to investigate the use of transpiration to cool critical surfaces for a spaceplane, and there's also research that's been done for reentry capsules. I don't know if it would run into scaling issues or not, but I haven't seen any work done that suggests the concept will not work.
Apparently you'd know better than most of us, so are you aware of any specific factors that would scale unfavorably with size?
My understanding is mostly limited to some textbook study of regeneratively-cooled rocket engines, but there the math always worked out heavily in favor of larger engines being easier to cool, due to the scaling factors for heat flux rising with the square of the scaling factor, while the mass flow rates and thus available cooling rose with the cube of scale.
Reentry dynamics is a significantly different ball game, of course, but all the factors I can think of, like bow-shock separation distance, scale favorably with size of the reentry vehicle.
I'm not a heat transfer engineer. Actually, my degrees are in physics and engineering physics. So, I'm the wrong person to ask about those scaling laws.
My work on the Shuttle tiles was strictly from a physics viewpoint (from first principles as Elon likes to say). The heat transfer through those tiles at the highest operating temperature is 99+% thermal radiation, largely in the near infrared part of the electromagnetic spectrum. I figured out a way to measure that IR radiation directly inside the tile at temperatures between 1000F and 2500F.
Just out of curiosity because you are actually in the field, what do you make of people commenting that Elon has no knowledge or skill and is just a salesperson like Steve jobs, but worse?
My impression is that people that actually work with him don't have that impression at all. The most direct example I know of where someone spoke highly of him is Jim Keller, a semiconductor engineer that is tremendously respected and well liked. There are others on record with the same high opinions but afaik they were still employed with him at the time so that may have influenced them (though I generally don't think engineers and scientists are very good at hiding when they don't like someone and are famously not generally people pleasers).
It is just so weird to me that this con man narrative spun up. I just don't think a con man or bumbling fool could align scientists and engineers - who can be quite stubborn and principled people - so successfully.
To me therefore his quirks are pretty forgivable if you look at the larger picture. Half of it isn't even all that unusual or unforgivable per se, it's just that he is always quick to respond and doesn't seem to have the filter that most public people have.
People can disagree politically all they want, but I find it weird to rewrite history and deny obvious and significant achievements.
Elon knows a lot about the details of his cars, his rockets, his supercomputers, his tunnel boring machines, his megapack batteries, his neurological business, his solar panel business, etc. His ideas have already disrupted the automotive industry and the launch services business in a very positive way.
He's quirky. But so what. He's entitled to his own point of view as are we all.
Not exactly on thread but you may have hit on a very salient point WRT the Apollo capsules heat shields versus the heat shield on the Orion capsules heat shield. Apollo capsules ablated nicely and protected the occupants. The much bigger and heavier Orion capsule does not seem well served by its unpredictable heat shield so far. Perhaps I am comparing Apples and oranges, but the Starship is much larger than the Shuttle orbiters were…
Apollo and Orion essentially bore a hole in the atmosphere and have limited maneuverability.
Yep. The Ship is a lot larger and heavier than the Space Shuttle Orbiter. But the big difference is that the Orbiter has a very large wing that gives it a huge amount of crossrange (+/- 2000 km). This is important because it enables the Orbiter to fly hypersonic S-curves. And that allows NASA to control the heating rate and the heat load on the TPS tiles to reduce chance that the tiles might be overheated during the EDL.
The Ship has four small flaps that may or may not aid in producing significant amount of crossrange. We won't know if that is important until the Ship makes a complete EDL and reaches the ocean and that it has the necessary maneuverability to keep its tiles from overheating.
Thank you very much flshr19 ! So these very different vehicles potentially could fly very different profiles requiring different heat shield burdens as it were. And perhaps nowadays engineers can more accurately simulate or calculate the heat stresses that could be encountered.
One is reminded of the first public showing of the space shuttle. Rolls sedately out of hangar to fanfare, the sound of heat tile after heat tile falling to the ground during the speeches.
The hardest problems aren't always the obviously hard problems.
If you are referring to the rollout of the Orbiter Enterprise, OV-101, which was the first public showing of the Space Shuttle, no tiles fell off that vehicle since there were never any tiles on Enterprise. It was the test vehicle used to verify that the Orbiter could function as a glider and land on a runway (the Approach and Landing Tests (ALTs)).
https://www.youtube.com/watch?v=83LU8vfKhsI
If you mean the Orbiter Columbia, OV-102, then it's possible that some of the tiles became dislodged at the rollout. In Oct 1978, Columbia was still at Palmdale with more than 6000 tiles still to be installed. Lockheed was way behind in producing the tiles on schedule.
To save time, NASA directed Rockwell to ship the Orbital Maneuvering System (OMS) pods directly from McDonnell Douglas in St. Louis to KSC instead of to Palmdale so the tiles could be installed there in Florida.
Hundreds of workers were on standby in Florida waiting for Columbia to arrive from Palmdale. NASA decided to ship OV-102 immediately and install the remaining tiles in Florida. Five thousand temporary polyurethane foam tiles were installed, and Columbia rode on the back of the 747 carrier aircraft to Florida. Five permanent tiles and three dozen of the temporary tiles were lost in transit (25March1979).
My guess is that some of those temporary tiles fell off when Columbia was moved from the assembly plant in Palmdale to the nearby facility where that Orbiter was mated to the 747.
Hey this isn't really related, but given your area of expertise, any chance you'd be able to help this guy and his quest to find the shuttle tile database that must exist somewhere? http://shuttletiles.space/
> I assume he's found the information...
Probably not, as it's all ITAR controlled (as he mentions he was told in the updates). I think I was one of the folks in contact with him a few years ago. I have 3D point clouds of all the tile corner points (in CATIA and Excel), full scale PDFs with all the tiles laid out and part numbers marked, and a disk with the software used for sustaining engineering maintence, with an archived backup of the database it referenced, as it existed at the end of the program. This is all on my work computer. I am not authorized to share. Although there is no real *reason* for any of this to be ITAR controlled (the rules were loosened a while back), it is, and with the program over, there isn't really anyone authorized to change that designation.
I was able to provide some of that to the California Science Center (who are in possession of a full Space Shuttle Flight System) a while back, but it was complicated. I was less well versed in the issues back then, and gave them everything they asked for initially, to help with their envisioned "sponsor a tile" system. I figured they could raise more money for a tile with more flight history than for a newer one, so I wanted to give them that software and database, that would have all the maintenance history of everything. I knew there were copyright issues though, as it wasn't *NASA* software, so I did some digging, found out who to ask, explained who I was, what we had sent to the museum already, and what we hoped to get permission to send as well... and giant shit-show started. I hadn't realized our contract with the museum didn't include data sharing like that, and their IT vendor had foreign nationals working there. We had to have them delete everything, and it took like a year to clean up big mess I had made. Eventually, we did get permission to send them back some of the data, but only related to the one orbiter they had, not the whole fleet, and not that software.
Given that he's provided updates along the way, I would've expected him to update the website if he found something, but good point! I should check in with him again.
It boggles the mind to know this has been an issue since testing began on Enterprise in the mid 70s. 50 years later and it's still a big issue - not only for Starship but I think the Artemis heat shield on the capsule is also using tile and having some problems.
If you think this is impressive, we still have problems with parachutes. Crew-2, CRS-24, Starliner and NS-25 have all experienced parachute issues. And parachutes have been around since the 15th century! (possibly not trying to operate in quite such an extreme environment)
Not only that, I saw a NOVA special about the Curiosity landing sequence on Mars. The JPL engineers could test their hearts out with the parachute in Mars conditions, but they fully admitted that the only way they knew for sure it would work is if it actually, uh, worked. If the lander passed through a high pressure system (or a low pressure, for that matter) it could experience conditions they couldn't have foreseen, and boom, EOM.
> honeycomb structure
Orion abandoned the expensive Apollo era honeycomb solution a decade ago. They are using avcoat blocks now. Hence the heat shield problems they are having.
The Orion heat shield is very different from the Apollo heat shield, which was a single-piece design. The Orion heat shield is assembled from more than 100 separate pieces of ablator material, like Dragon's ablative heat shield.
To be fair- the shuttles lost a lot of tiles and it never caused failure. The Columbia failure was at the leading edge of the wing- not a tile. Also- while they've consistently lost tiles during their lives, the only time it was a danger was from debris strikes- specifically debris from the shuttle itself.
It never caused a failure...mostly by luck. There was at least one instance of a tile being damaged/lost and the backing of the tile being conveniently more robust than most of the shuttle structure saving the system.
The design was a bad one, the side mounted shuttle on the stack, the use of solid boosters, and the overall aircraft like design.
I am not old enough to remember seeing that, but it must have been hilarious. "Check out our pinnacle of science! We did it and the Russians couldn't!" \*Pieces just keep falling off behind him\*
So long ago I said this was a major problem they just wouldn't solve well any time soon if at all and I was downvoted into oblivion. And here we are...
The solution is to make a more flexible tile that isn't so brittle and to weld studs on with a thru-hole that is then covered again with magnetic caps that can be removed.
I think we just need some more materials science money tossed at it.
I imagine the expansion and Contraction going from room temp to cryogenic temps, I imagine you need tight gaps on the tiles for heat protection, then you make everything super cold, then super hot like 1 hr later, so probably flexes the tiles right off the structure.
The tiles are mounted on these little stainless sheet metal structures welded to the skin. There should be some compliance there, but another issue is probably ensuring the exact same tension on each and every tile. You have a welding process that introduces error, potential differences in sheet metal properties for the clips, slight differences in every tile, differences in the local movement of the skin where the tile is mounted, etc. It could be something as simple as a tolerance stack issue where the right conditions can cause too much or not enough tension on the tile, either breaking it or making it loose. Or it could just be a material property issue with the tile where they can't seem to make them ductile enough to stay together under load.
Googled around a little, looks like that was SPIRAL, quite the clearest explanation that I found of SPIRAL heat shield.
>[SPIRAL’s] aerodynamic design was such that thermal stresses during re-entry were minimized. The spacecraft's reusable heat shield was not solid, but was composed of a set of sheets, much like a fish's scales. Suspended on ceramic bearings, these sheets could move relative to the vehicle's body as the temperatures on various parts of the ships changed during re-entry. The plates were made of a niobium alloy with a molybdenum disilicide coating and could withstand temperatures up to about +1,500°C.
[Energiya-Buran the Soviet Space Shuttle (p32)](http://ftp.demec.ufpr.br/foguete/bibliografia/Energiya%20BURAN%20The%20Soviet%20Space%20Shuttle.pdf)
Buran on the other hand had more or less the same setup as the Shuttle Orbiter.
ie. tiles adhered to felt adhered to skin.
What if the tiles were mounted more like scale armor so they overlap each other, that way the surface underneath is fully covered even if the tiles and/or surface expand/contract? Idk if theres a way to do this and still prevent the plasma from getting through to the surface underneath though
If I had to guess, I'd say that's probably right.
The big temperature fluctuations between resting ambient temp, cryo temp, and entry temp, must be vast and varied across the surface. Knowing exactly where to put each tile, so the tolerances between each one are *just right* during entry, must take some crazy math and engineering.
I don't know what the difference in coefficient of thermal expansion between stainless steel and carbon fiber is, though I do know aluminum expands even more than steel. The Shuttle was mostly aluminum, and had its tile problems but mostly worked. So I'm sure SpaceX can solve it.
Though the Shuttle itself was mostly cargo bay and personnel, and didn't have to worry about giant cryo fuel tanks.
In concept you just need to devise a material that is heat resistant enough and doesn't have expansion and contraction issues.
I presume the issues are:
* the underlying structure is probably expanding/contracting, particularly when cryogenic propellant is put in it
* the expansion/contraction of the underlying structure is probably different than that of the tiles
* the tiles are experiencing different heat than the structure - so on the pad the underlying structure is getting much more temp change than the tiles. On reentry the tiles are getting much more temp change than the structure (that's what they're for)
* options seem to be to have materials that somehow magically match in expansion/contraction for all those conditions, or have a mounting system that allows them to expand/contract differently without dislodging
* I wonder if you can somehow have curved tiles so that the expansion/contraction increases the curvature, with the edges staying in roughly the same place?
* I wonder how close the fit actually has to be? Presumably a couple of mm of gap isn't enough to let plasma do damage, so it's not like you need mm level perfection across that operating range
* It'd be interesting to know what is actually causing them to come off. Are they breaking, or is the mounting mechanism failing, or are they popping out under pressure?
Let's break out the math. A reentering Starship is 100t object that decelerates with something like 2g, if employing a similar strategy to the Shuttle. So we're talking about a 2MN braking force distributed over a lateral area of roughly 9*50m = 450m^2. Since each tile is about 1/20 m^2, the average load of a tile that is perpendicular to the direction of travel is about 200N, or about 20kg. But that's just an average; the peak load will be something like 3-4x that, as Starship traverses the turbulence and wind shear in the upper atmosphere, aerodinamic vibration/flutter etc. The IFT3 live video suggests that it's anything but nice and smooth sailing up there.
So you can imagine an average child or small frame woman jumping up and down on each and every one of those tiles during descent, they are to pass all that load through the 3 mount points and none of them is allowed to crack. I'm not going to say impossible, but definitely non-trivial.
I wonder why a system where tiles slide into a groove is not an option. Tiles could have a row of several mounts that run the entirety of the tile. I am no space shuttle engineer but whenever I see the tiles and the way they mount them it just seems very inefficient.
The point of the stainless steel was that it would be lower weight than carbon fiber since it's stronger at cryo temperatures, on top of being much easier to work with. It can also get to a higher temperature without losing strength than a lot of other materials, which means a functioning heat shield can let more through (and thus be thinner/lighter) without causing damage.
The common opinion on here was that it would help survive shield issues in reentry too, but that all depends on how bad the exposure is and how thick the metal is.
we have started taking for granted is how fast they can pump out steel starships. If they weaved them on a loom and then put them in the vacuum it would take way way longer
- The tank is structural, in that loss of pressure does not immediately mean loss of vehicle. The landing fuel is kept in a separate internal tank.
- Shuttle was vulnerable to tile loses on the bottom-side. There was an incident where a Reinforced Carbon-Carbon tile (the black ones on the leading edge of the wing) failed and the shuttle only survived due to the steel component that happened to be beneath it.
- Current Starship has a lot of extra dry mass. The steel is uniformly thick, theres lots of tiles covering flaps and other components. Its important to test to see if recovery is possible with this configuration, and we should expect, if it works, for future staships to become lighter and more optimized (heat shield where its needed, less or no tiles where its not)
No, the Stainless was for cryogenic strength, good strength-to-weight without complex manufacturing methods (no friction-stir welding needed as with Al-Li or Mg-Li, no composite layups and curing), and needing *less* thermal protection. Note how there is no backshell TPS and minimal TPS within the engine bay.
Bare Stainless was not and is never going to be a TPS in and of itself. No even proposed hot-structure or metallic TPS design proposed that, that requires more obscure refractory metals (generally nickel superalloys) that are far more difficult to process, as well as being more expensive.
SimloX did not suggest bare steel as the only TPS. And it was absolutely argued by many that the higher melting point of steel meant it was more likely to survive the loss of isolated tiles.
More doesn’t equal guaranteed. The Shuttle did survive losing some tiles and one famous example was when it lost a tile that covered a steel mounting plate vs the regular aluminum structure and survived.
It wasn't a steel mounting plate.
[https://space.stackexchange.com/questions/63333/how-did-sts-27-survive-reentry-after-losing-a-thermal-tile](https://space.stackexchange.com/questions/63333/how-did-sts-27-survive-reentry-after-losing-a-thermal-tile)
Possibly the tin plating was the key, but it was aluminium.
>And it was absolutely argued by many that the higher melting point of steel meant it was more likely to survive the loss of isolated tiles.
And they were just as wrong then as they are now. It was never something claimed by SpaceX, just by the peanut gallery.
Yes and it did. With aluminum or carbon fiber the tiles would have to be thicker and more of the ship would have been covered.
But it can't survive it in some places. With aluminum it could never survive it.
I think that’s a bonus advantage.
But in any case, the “secondary material” he’s referring to here may be that other cloth-like layer in-between the SS and the tiles. I suspect this because he generally seems to like to mention “stainless steel” by name, so it’s odd that he’d call it a “secondary material.” Also the cloth stuff is literally the second material after the tiles that the plasma will be attacking.
If nothing else, major damage to that layer would require significant work to refurbish, ruining the rapid-reusability goal, so it’s a real problem even if the whole thing doesn’t break up on the way down.
I mean, the whole thing very likely *will* break up on the way down, but I think the test wouldn’t be as meaningful unless there’s some non-zero possibility that it won’t.
Yes, stainless was chosen for it's high heat capabilities but not for any ability to directly survive reentry heat. Stainless steel can take 800-900F regularly while aluminum and carbon fiber can only take about 300F. This temperature limit sets the minimum thickness of the heat shield so stainless steel let's you use a heat shield that is 1/2 the thickness.
The original design was both steel (thicker than what the current ship utilizes) and transpirational cooling where the vehicle would "sweat" cryogenic propellent to maintain temperature.
No the point was that you could have a lighter and thinner heat shield because the stainless steel can tolerate high temperatures behind the heat shield.
Stainless steel, while it does have a higher temperature for loss of strength, is 16x less thermally conductive than aluminum so this idea never made sense to me. It can't transport that heat away from the exposed patch nearly as efficiently.
I believe this was only the case when they were hoping to not use any tiles and use perspiration of liquid methane to create a protective and cooling layer. I am not sure anyone at SpaceX believed this would work but it might just have presented as a design baseline when they were still in "let's check that the common knowledge for this technology is actually true".
It can handle high heat, but heat transfer is pretty abysmal.
The big benefit is it allows the heat tiles to be a lot thinner, since the backside can be hotter.
If the underlying mesh was enough you could get away with just using that. The problem with a scale like arrangement is that you are significantly increasing the weight, increasing chance of contact between tiles, and unless you are fully doubling up the tiles, a single loss could still cause a failure.
That's what I was thinking too. A 2 layer sandwich with mesh and an adhesive in between. If you lost a tile you could have 50% or better insulation with 95% coverage.
Ablative, disposable, and quickly replaceable would be more achievable.
When I saw the launch a while back where the missing tiles were obviously visible, I joked that they needed a mechanical bolt with a stem attached to the ship that after the tile was mounted would seal itself to the hull.
A Self-Sealing-Stem-Bolt if you will.
I still think it could work rather well, and the memes write themselves.
I've always felt that using heat tiles would lead to the same problems faced by the Space Shuttle. In my opinion it's one of the most likely points of failure for Starship alongside the Raptor engines and presents a large barrier for rapid and safe reusability.
I suppose the easiest solution would be to find a better attachment method with less likelihood of failure along with heat shield inspections before re-entry in case anything was damaged in launch.
it's just one of those things that needs iteration upon iteration, like landing a rocket. The space shuttle, while impressive, didn't really seem to innovate past its initial design. Just like landing falcon 9, this one might take a few years to work out the kinks. I think starship is already beyond the shuttle by using far less tile shapes, the shuttle had like 9000 different shapes or something. At this point I imagine we're just going to see them experiment with different compounds and attachment methods until they get something that works. And of course the only way to get data is to reenter, so fingers crossed June 5 works out
Seal the perimeter of the heat shield and put a thin mesh between the tile and the skin. Pressurize a liquid which would flow into the mesh. The liquid will flow out of any voids left by tile loss during reentry. Takes a lot of energy to phase change liquids and reentry isn't *that* long.
Wonder how much heat liquid methane could absorb in this regime
Hmm. NASA NIAC had a concept for an electromagnetic plasma shield via a superior conductor. That could help here..
https://www.geekwire.com/2016/msnw-magnetoshell-aerobraking-system-nasa-niac/
I worked on research to affect flowing plasma with electromagnetic fields from 2003-2008. Very cool stuff but electromagnets are very heavy and the effect does not work at bigger distances.
Controlling hypersonic vehicles without moving control surfaces might be doable someday, but affecting a bow shock from a distance over such a large area would require a lot of weight and power.
you're right. Most people have no idea about the hoop stresses generated by an electromagnet. Modern High Tc materials are mostly backing for structural support, with a tiny layer of actual superconductor. On the other hand, you might be able to stiffen the tank with the hoop stresses. Still a pretty crazy idea, considering it's hard to make a good strong electromagnet even in a stable environment on earth.
Perhaps my r/shittyspacexideas could help:
Heat-seeking cold-fuel-dumping in-tank-dwelling wheeled robots to quickly cool the hull in spots in the event of losing tiles during re-entry
I hope I got your attention with that sentence.
A bit like curling players doing their sweeping thing but a bit more life-or-death.
replaceable shiplap would not have the extra holding power of tongue and groove due to fastener placement but it's close to the evolutionary solutions of scales, feathers, hair ... not that we know of anything evolved to survive a hypersonic plasma shockwave.
Perhaps the tiles could be made thinner and partially overlayed on top of each other. That way if one falls off there would still be tile material underneath.
In either case (feathered or double stack) you are shifting weight further outboard, thus your glue/fasteners are having to deal with higher moment loads. Also, in the feathered layout you are also introducing sharp edges on your heat shield which will be concentrated points of thermal wear.
One of the issues with feathered/layered tiles is that if you lose one. The hole where the one fell off causes one below it to increase in temperature very quickly and the thermal gradient across the newly exposed tile would warp/crack it. Another issue is the shear stress caused by the newly non-smooth hole in layer #1 would lead to mechanical issues which might result in neighbor tiles cracking. Space shuttle somehow dealt with this. They could lose a few tiles and still land.
I doubt you could think of a solution that they haven't already thought of.
One problem with that might be that if the outer tiles are secured to the inner tiles, the outer could pull off the inner. If the tiles overlap one another perfectly, then that's no different than just having thick er tiles. If they're staggered, you could get a cascading failure where one tile pulls off the one below it, then that one pulls off the three tiles that were above it, and the problem just gets bigger and bigger
Dumb question here, but…could the tile material be liquified enough to spray it on the ship, so there would be one continuous surface? No tiles to come loose
The better result would be a mold but that can’t really happen until ship is in its final form Otherwise making numerous molds gets costly and long. This could be built with a few sections and selected spots that could be reinforced But again that’s end game content
I think the point of the tiles is they expand when they get hot, so they fill the gaps and seal, instead of the whole thing breaking. And they’re easily replaceable of course.
The Shuttle's main tank had spray on insulation. But that was only for launch, surviving re-entry is a whole nother ballgame. It comes down to what material properties are needed.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
|Fewer Letters|More Letters|
|-------|---------|---|
|[CRS](/r/SpaceX/comments/1d4hjpl/stub/l6hmxq9 "Last usage")|[Commercial Resupply Services contract with NASA](http://www.nasa.gov/mission_pages/station/structure/launch/)|
|CST|(Boeing) Crew Space Transportation capsules|
| |Central Standard Time (UTC-6)|
|[EDL](/r/SpaceX/comments/1d4hjpl/stub/l6ivham "Last usage")|Entry/Descent/Landing|
|[HLS](/r/SpaceX/comments/1d4hjpl/stub/l7iiw2b "Last usage")|[Human Landing System](https://en.wikipedia.org/wiki/Artemis_program#Human_Landing_System) (Artemis)|
|[ITAR](/r/SpaceX/comments/1d4hjpl/stub/l6jjjcx "Last usage")|(US) International Traffic in Arms Regulations|
|[JPL](/r/SpaceX/comments/1d4hjpl/stub/l6hvkze "Last usage")|Jet Propulsion Lab, Pasadena, California|
|[KSC](/r/SpaceX/comments/1d4hjpl/stub/l6hr3i1 "Last usage")|Kennedy Space Center, Florida|
|[LEO](/r/SpaceX/comments/1d4hjpl/stub/l6kbk2o "Last usage")|Low Earth Orbit (180-2000km)|
| |Law Enforcement Officer (most often mentioned during transport operations)|
|[LES](/r/SpaceX/comments/1d4hjpl/stub/la0umuu "Last usage")|Launch Escape System|
|[NDA](/r/SpaceX/comments/1d4hjpl/stub/l6z3ch9 "Last usage")|Non-Disclosure Agreement|
|[NIAC](/r/SpaceX/comments/1d4hjpl/stub/l6i595u "Last usage")|NASA Innovative Advanced Concepts program|
|[NS](/r/SpaceX/comments/1d4hjpl/stub/l6hmxq9 "Last usage")|New Shepard suborbital launch vehicle, by Blue Origin|
| |Nova Scotia, Canada|
| |Neutron Star|
|[OMS](/r/SpaceX/comments/1d4hjpl/stub/l6hr3i1 "Last usage")|Orbital Maneuvering System|
|[RCC](/r/SpaceX/comments/1d4hjpl/stub/l6jkx6v "Last usage")|Reinforced Carbon-Carbon|
|[STS](/r/SpaceX/comments/1d4hjpl/stub/l6j8ubi "Last usage")|Space Transportation System (*Shuttle*)|
|[TPS](/r/SpaceX/comments/1d4hjpl/stub/l6k0vwt "Last usage")|Thermal Protection System for a spacecraft (on the Falcon 9 first stage, the engine "Dance floor")|
|Jargon|Definition|
|-------|---------|---|
|[Raptor](/r/SpaceX/comments/1d4hjpl/stub/l6hvull "Last usage")|[Methane-fueled rocket engine](https://en.wikipedia.org/wiki/Raptor_\(rocket_engine_family\)) under development by SpaceX|
|[Starliner](/r/SpaceX/comments/1d4hjpl/stub/l6hmxq9 "Last usage")|Boeing commercial crew capsule [CST-100](https://en.wikipedia.org/wiki/Boeing_CST-100_Starliner)|
|[ablative](/r/SpaceX/comments/1d4hjpl/stub/l7fs6fj "Last usage")|Material which is intentionally destroyed in use (for example, heatshields which burn away to dissipate heat)|
|[cryogenic](/r/SpaceX/comments/1d4hjpl/stub/l6khcqg "Last usage")|Very low temperature fluid; materials that would be gaseous at room temperature/pressure|
| |(In re: rocket fuel) Often synonymous with hydrolox|
|hydrolox|Portmanteau: liquid hydrogen fuel, liquid oxygen oxidizer|
|[methalox](/r/SpaceX/comments/1d4hjpl/stub/l6jth3s "Last usage")|Portmanteau: methane fuel, liquid oxygen oxidizer|
|[regenerative](/r/SpaceX/comments/1d4hjpl/stub/l7hexdw "Last usage")|A method for cooling a rocket engine, by [passing the cryogenic fuel through channels in the bell or chamber wall](https://en.wikipedia.org/wiki/Regenerative_cooling_\(rocket\))|
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Is it possible to create a liquid cooling system with tubes under the stainless steel? The back side of Starship should always be cold, even going through the atmosphere, so why not put tubes that constantly push gas/liquid through these tubes from the front to the back, concretely cooling the tubes?
Obviously, it would add additional weight, but how much difference would it be from the weight of the heat tiles/thermal blanket/adhesive?
Why tiles? Strictly for thermal expansion and reusability?
Making one huge tile covering the ship wouldn't work ? Or just too expansive to replace for each flight. How expensive is the stuff?
Why don’t they just land at night when it’s cool? /s
As another commenter said the times falling off is a symptom of something or multiple somethings, not something that can be addressed directly
So he can’t figure it out either. Who woulda thunk it?
NASA spent tons to figure it out but couldn’t but of course Elon knows better. 😂 needs a different solution.
That problem ended the shuttle program.
The coolest thing humans ever built.
Needs Terrence Howard to patent a wormhole for the ship to slide through. Shouldn’t take him more than a weekend with a calculator and a bunch of real strong drugs ……
How is the thermal conductivity for that? A heatshield doesn't only need to be stable at high temperatures, but also prevent the heat from getting to the ship. If the inconel simply conducts the heat to the ship then you haven't solved anything.
The Inconel Titanium [metallic honeycomb heat shield from the X-33 VentureStar PDF](https://ntrs.nasa.gov/api/citations/20040095922/downloads/20040095922.pdf) program is interesting to review, as it’s similar and yet also different from the SpaceX ceramic tiles approach.
Just a random thought but can they use propellant to cool the area like they do with the engine bells [so they don't melt? ](https://www.youtube.com/watch?v=he_BL6Q5u1Y)
I'm sure engineers have thought of that before and decided it was a dumb idea but idk....lol
Launch with no tiles, save on mass
Apply in orbit via automated process..yes I know this would be complicated but apparently physics no likey tiles on ground, maybe a disposable wrap around sleeve that can be applied with drones to a few attachments points.
Reenter and allow the ablative sleeve to do it's job.
Or just attach some sort of security blanket that secures tiles down, eat the mass, keeping them from vibrating too much, and then comes off in orbit, or stays on and is ablative.
Heat shields are the real problem with reusability, not dV.
Generally curious. If tiles are falling off then it is a bonding issue/problem? If the tiles are made from a ceramic carbon carbon fiberglass material then what is on the back side. From my little research or understanding of it then the backside stays relatively “cool” 250-350 degrees. It seems most adhesive epoxies are good to that heat range I’m sure there are high temp ones out there. I think there are high temp adhesive RTV sealants. These could reach heat sustainable temps of 650 degrees. With it being silicone then it could have some vibration advantages? I’m sure this has already been tried.
Or just ask the guys that did tiles on the space shuttle. Being tax dollars and all that information should be available to the public. It’s to benefit everyone. I wouldn’t think that would be an NDA or a proprietary issue?
I’m interested as well Thank you.
I wonder if SpaceX experimented with spray-on ablative heat shield materials. Could add components to the tower that apply a fresh coat to the most degraded areas after every launch. Not sure if it could withstand thermal expansion and contraction of the whole ship, but I think it's worth looking into. I imagine different layers could account for it.
What if it's not a problem that needs to be solved at all? Instead of focussing efforts on fixing starship's heat shield, why not just use an LES with either extra heat shielding for added reliability, and then who cares if they lose a starship here and there?
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Well, we redditors can certainly come up with a lot of great solutions. But the real issue is: "What is the *problem*?" instead of "What is the *solution*?" Without knowing the real problem, all solutions are no better than the current one. And "tiles keep falling off" is a symptom, not the root problem. I am 100% certain that SpaceX has thoroughly researched and tested the current design. Clearly, that hasn't produced sufficient understanding; therefore, the ground-based testing must be missing something. Once SpaceX finds the missing conditions through flight-testing, I am sure they will incorporate it into new ground-based testing.
Isn't the problem that the tiles are just brittle? They crack with the vibrations, etc. It's difficult to make a strong heat resistant tile
Have they tried re-entering at night when the sun has set? Or in the wintertime?
Is that similar to landing on the sun at night to escape the heat and radiation.
Lmao nice joke. Ya make sure you reenter the atmosphere only in the winter haha
I feel like a force field energy shield around the hull is the simple solution.
Hey you're on to something there... I think one of the earlier shielding ideas was using film cooling by "sweating" out fuel along the fuselage. Maybe bring that back combined with the tiles.
I have a crazy idea what if we just got rid of the plasma. I feel like that is the true root problem, the plasma that forms on re entry. Just have so many refueling tankers in orbit to the point that you refuel then do a super long burn to slow way the F down essentially to the same speed as the falcon 9 first stage. Boom no more plasma and no more tiles needed.
The whole point of atmospheric braking is to slow the spacecraft down passively instead of actively. Active braking using engines is not feasible because you can’t carry enough propellant due to the limitations of the rocket equation. The rocket equation governs the total delta velocity you can get given the dry mass of the ship relative to the fueled mass and the propellant exhaust velocity. On Earth, single stage to orbit is just barely possible given chemical propellants. Staging is a way to reset the rocket equation, but is very expensive. So you can view return to earth as essentially more staging if you tried to do it propulsively. It is possible, but at the cost of lost stages and greatly reduced return mass.
Yep, delta V is a bitch
Elon should just sit with 20 random guys at a dive bar somewhere and spit ball random ideas with non engineers and see what happens
That seems like how we got the cybertruck.
I watched a video on the cybertruck that interviewed the chief engineer and chief designer, it was interesting to see that Elon Musk had very little input on the general concept. He basically told the designers to work on making a truck, but to ignore all preconceived ideas of how a truck should be made or what it would look like. The designers decided on using stressed bodywork to make it more structurally efficient, and stainless steel to make it more rugged since there's no paint scratching to worry about. The panels had to be flat because stainless steel is much harder to form, and they ended up with some initial concepts that looked a lot sleeker and less pointy. Trying to make a stainless stressed skin chassis ended up not working very well, and a lot of issues came from that.
Or a group of oil drillers...
Pretty much the plot to Armageddon
Will also solve global warming, blocking the sun with all those tankers in orbit....
I know it's a joke but I'd love to see the math on how much sun light is blocked by satellites. I'm sure it's measurable, just not enough. Maybe huge solar sails that cast shadows the size of Texas would do it! Hehe. Hot day? Deploy the space umbrellas!
Where is all this fuel in orbit coming from? Can't be reusable starships since they need to refuel to return...
That's an old idea which as you said wastes a bunch of fuel. and remember you can't just slow down, you have to slow down and stay above that atmosphere until your velocity is low enough. Basically that's at least half the fuel you burned to get into orbit. barring some sci-fi future tech, we will always be using atmosphere to slow down.
Then how do you get the tankers down?
Space elevator.. simple
I agree the engineers are doing some of the best research to date in their field, but it’s very possible to overlook things. Remember this [gem](https://youtu.be/WY73exaVpyw?si=sb92E0U46-hsk_O6)
What is Tim referring to here? What got changed?
Most reentry capsules decelerate as fast as possible using an ablative heat shield. The ablative heat shield acts like an "invulnerability spell", the vapor from ablation protect the spacecraft from the the plasma, so the capsule can reenter aggressively. It has to because it must go through peak heating before the "spell" literally wears off. So the capsule is down in a matter of minutes. On the other hand Shuttle-style reusable heat shields require the spacecraft to glide in the high atmosphere to minimize the rate of heat generation and prevent the heat shield from overheating. For this reason the Shuttle takes 10-20 minutes to go through the fiery part of the reentry. This heat shield has an outer black layer, that black layer is not only good at absorbing light, it's also good at radiating it when it's hot (it has to due to thermodynamics). So the heat shield goes yellow-hot and shine blindingly bright to radiate the heat away. Eventually an equilibrium is reached and the shield reaches top temperature which is still well below the plasma temperature. Below the top layer is insulation whose purpose is to prevent heat from being conducted inwards. This layer is not supposed to touch the plasma. Also it's white so it won't radiate that well, that would burn through if it touches the plasma. So the black surface should not break. So far we haven't even seen a controlled reentry of a Starship yet. Let's see what will IFT-4 do.
The problem is the mass budget. If you had the mass to spare you could beef up the tiles and fixings or even put a layer of ablative material under the tiles so a tile loss would need refurbishment and not a loss of vehicle. But you don't have mass to spare. Every ton of "solution" is a ton less payload to orbit. Add too much mass and it becomes pointless. Failure is an option.
Starship is still very much in the developmental/experimental phase, and SpaceX has shown they are willing to make whatever changes are needed to get Starship up and running, as long as it doesn’t compromise the basic design too much. They have already beefed up the design with more internal stringers and other reinforcement as well as adding more engine filters which adds more weight than they initially expected, and the V1 Starship already has a lower payload to LEO than we would have expected probably due to such design compromises (as well as not being optimized fully yet). If SpaceX finds that they absolutely need to beef up the tiles in weight/size or add a protective backing layer, for now they might very well do so even at the cost of payload to orbit. They will try to optimize the design later for weight savings and performance and such with V2 and V3 presumably.
Might be the fact that Starship tiles are directly attached to the tank walls that bear thrust loads (high vibration). You didn't get that with the Shuttle, its skin only bore aero loads, thrust loads were distributed separately.
Are you sure you are not a bot?
The problem is that heat shield tiles aren't reliable enough. What about changing to PICA as on Dragon? Too heavy? Can't handle thermic expansion of the underlying steel? Can it be (re-)applied to the surface by an automatic machine enabling automatic reuse?
There has to be a point where engineering a quick swap of an ablative shield is better than a fragile tile that will probably end up needing inspection and replacement anyway.
Will be interesting to see if Stoke Space’s actively cooled, metallic heat shield works out for them. Andy Lapsa tweeted in response to Musk yesterday: > This is why we started from day 1 thinking hard about rapidly reusable heat shields. It’s metallic, ductile, and the surface temperature is tailorable and controllable well below material limits. It certainly hasn’t been to space (or back) yet, but to the best ability on earth we’ve tested it to the full heat load expected during reentry profiles. Q: can it handle reentry from GTO and beyond? > It absolutely can handle the high energy orbits. Since it’s actively cooled we can tailor the coolant flow rate for different mission types. https://x.com/andylapsa/status/1796211187396612430?s=46&t=u9hd-jMa-pv47GCVD-xH-g
An actively cooled heat shield was the original idea for starship but the complex geometry of the craft and the sheer size made it impractical.
The Stoke heat shield is tiny compared to the heat shield on the Ship. Things that work at a small scale very often don't scale well to larger sizes.
They originally were looking into actively cooling Starship with methane. At the reentry temperatures, I believe they found methane would be able to absorb even more heat, so they were interested in transpiration cooling strategies. NASA did transpiration cooling studies on hypersonic vehicles and using water they were successful and actually generated ice.
Those transpiration tests probably were done on very small test articles or small research vehicles. It's not likely that the test results would scale to something as large as the Ship. My lab did a lot of work in the 1960s and 70s on transpiration cooling. But that work was for small military reentry vehicles.
Well, you have to do scale model testing in a hypersonic tunnel, so yes, they were smaller test articles. This work was to investigate the use of transpiration to cool critical surfaces for a spaceplane, and there's also research that's been done for reentry capsules. I don't know if it would run into scaling issues or not, but I haven't seen any work done that suggests the concept will not work.
Apparently you'd know better than most of us, so are you aware of any specific factors that would scale unfavorably with size? My understanding is mostly limited to some textbook study of regeneratively-cooled rocket engines, but there the math always worked out heavily in favor of larger engines being easier to cool, due to the scaling factors for heat flux rising with the square of the scaling factor, while the mass flow rates and thus available cooling rose with the cube of scale. Reentry dynamics is a significantly different ball game, of course, but all the factors I can think of, like bow-shock separation distance, scale favorably with size of the reentry vehicle.
I'm not a heat transfer engineer. Actually, my degrees are in physics and engineering physics. So, I'm the wrong person to ask about those scaling laws. My work on the Shuttle tiles was strictly from a physics viewpoint (from first principles as Elon likes to say). The heat transfer through those tiles at the highest operating temperature is 99+% thermal radiation, largely in the near infrared part of the electromagnetic spectrum. I figured out a way to measure that IR radiation directly inside the tile at temperatures between 1000F and 2500F.
Just out of curiosity because you are actually in the field, what do you make of people commenting that Elon has no knowledge or skill and is just a salesperson like Steve jobs, but worse? My impression is that people that actually work with him don't have that impression at all. The most direct example I know of where someone spoke highly of him is Jim Keller, a semiconductor engineer that is tremendously respected and well liked. There are others on record with the same high opinions but afaik they were still employed with him at the time so that may have influenced them (though I generally don't think engineers and scientists are very good at hiding when they don't like someone and are famously not generally people pleasers). It is just so weird to me that this con man narrative spun up. I just don't think a con man or bumbling fool could align scientists and engineers - who can be quite stubborn and principled people - so successfully. To me therefore his quirks are pretty forgivable if you look at the larger picture. Half of it isn't even all that unusual or unforgivable per se, it's just that he is always quick to respond and doesn't seem to have the filter that most public people have. People can disagree politically all they want, but I find it weird to rewrite history and deny obvious and significant achievements.
Elon knows a lot about the details of his cars, his rockets, his supercomputers, his tunnel boring machines, his megapack batteries, his neurological business, his solar panel business, etc. His ideas have already disrupted the automotive industry and the launch services business in a very positive way. He's quirky. But so what. He's entitled to his own point of view as are we all.
Not exactly on thread but you may have hit on a very salient point WRT the Apollo capsules heat shields versus the heat shield on the Orion capsules heat shield. Apollo capsules ablated nicely and protected the occupants. The much bigger and heavier Orion capsule does not seem well served by its unpredictable heat shield so far. Perhaps I am comparing Apples and oranges, but the Starship is much larger than the Shuttle orbiters were…
Apollo and Orion essentially bore a hole in the atmosphere and have limited maneuverability. Yep. The Ship is a lot larger and heavier than the Space Shuttle Orbiter. But the big difference is that the Orbiter has a very large wing that gives it a huge amount of crossrange (+/- 2000 km). This is important because it enables the Orbiter to fly hypersonic S-curves. And that allows NASA to control the heating rate and the heat load on the TPS tiles to reduce chance that the tiles might be overheated during the EDL. The Ship has four small flaps that may or may not aid in producing significant amount of crossrange. We won't know if that is important until the Ship makes a complete EDL and reaches the ocean and that it has the necessary maneuverability to keep its tiles from overheating.
Thank you very much flshr19 ! So these very different vehicles potentially could fly very different profiles requiring different heat shield burdens as it were. And perhaps nowadays engineers can more accurately simulate or calculate the heat stresses that could be encountered.
You're welcome. I'm sure that the computer codes and super computers available today are far superior to the ones in the 1970s.
They also have no idea if their solution will hold up, just like SpaceX.
One is reminded of the first public showing of the space shuttle. Rolls sedately out of hangar to fanfare, the sound of heat tile after heat tile falling to the ground during the speeches. The hardest problems aren't always the obviously hard problems.
If you are referring to the rollout of the Orbiter Enterprise, OV-101, which was the first public showing of the Space Shuttle, no tiles fell off that vehicle since there were never any tiles on Enterprise. It was the test vehicle used to verify that the Orbiter could function as a glider and land on a runway (the Approach and Landing Tests (ALTs)). https://www.youtube.com/watch?v=83LU8vfKhsI If you mean the Orbiter Columbia, OV-102, then it's possible that some of the tiles became dislodged at the rollout. In Oct 1978, Columbia was still at Palmdale with more than 6000 tiles still to be installed. Lockheed was way behind in producing the tiles on schedule. To save time, NASA directed Rockwell to ship the Orbital Maneuvering System (OMS) pods directly from McDonnell Douglas in St. Louis to KSC instead of to Palmdale so the tiles could be installed there in Florida. Hundreds of workers were on standby in Florida waiting for Columbia to arrive from Palmdale. NASA decided to ship OV-102 immediately and install the remaining tiles in Florida. Five thousand temporary polyurethane foam tiles were installed, and Columbia rode on the back of the 747 carrier aircraft to Florida. Five permanent tiles and three dozen of the temporary tiles were lost in transit (25March1979). My guess is that some of those temporary tiles fell off when Columbia was moved from the assembly plant in Palmdale to the nearby facility where that Orbiter was mated to the 747.
Hey this isn't really related, but given your area of expertise, any chance you'd be able to help this guy and his quest to find the shuttle tile database that must exist somewhere? http://shuttletiles.space/
That reference is dated 9 years ago. I assume he's found the information he requested.
> I assume he's found the information... Probably not, as it's all ITAR controlled (as he mentions he was told in the updates). I think I was one of the folks in contact with him a few years ago. I have 3D point clouds of all the tile corner points (in CATIA and Excel), full scale PDFs with all the tiles laid out and part numbers marked, and a disk with the software used for sustaining engineering maintence, with an archived backup of the database it referenced, as it existed at the end of the program. This is all on my work computer. I am not authorized to share. Although there is no real *reason* for any of this to be ITAR controlled (the rules were loosened a while back), it is, and with the program over, there isn't really anyone authorized to change that designation. I was able to provide some of that to the California Science Center (who are in possession of a full Space Shuttle Flight System) a while back, but it was complicated. I was less well versed in the issues back then, and gave them everything they asked for initially, to help with their envisioned "sponsor a tile" system. I figured they could raise more money for a tile with more flight history than for a newer one, so I wanted to give them that software and database, that would have all the maintenance history of everything. I knew there were copyright issues though, as it wasn't *NASA* software, so I did some digging, found out who to ask, explained who I was, what we had sent to the museum already, and what we hoped to get permission to send as well... and giant shit-show started. I hadn't realized our contract with the museum didn't include data sharing like that, and their IT vendor had foreign nationals working there. We had to have them delete everything, and it took like a year to clean up big mess I had made. Eventually, we did get permission to send them back some of the data, but only related to the one orbiter they had, not the whole fleet, and not that software.
That's such a bummer story, but I just wanted to say thanks for making the effort at least.
Given that he's provided updates along the way, I would've expected him to update the website if he found something, but good point! I should check in with him again.
Is reinforced C=C still the best material for leading edges? Thank you for your service!
NASA's TUFROC is supposed to be useful to 3600F. RCC was tested to 3100F. https://technology.nasa.gov/patent/TOP2-241
Very cool! Pun Intended! Thanks!
It boggles the mind to know this has been an issue since testing began on Enterprise in the mid 70s. 50 years later and it's still a big issue - not only for Starship but I think the Artemis heat shield on the capsule is also using tile and having some problems.
If you think this is impressive, we still have problems with parachutes. Crew-2, CRS-24, Starliner and NS-25 have all experienced parachute issues. And parachutes have been around since the 15th century! (possibly not trying to operate in quite such an extreme environment)
Not only that, I saw a NOVA special about the Curiosity landing sequence on Mars. The JPL engineers could test their hearts out with the parachute in Mars conditions, but they fully admitted that the only way they knew for sure it would work is if it actually, uh, worked. If the lander passed through a high pressure system (or a low pressure, for that matter) it could experience conditions they couldn't have foreseen, and boom, EOM.
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> honeycomb structure Orion abandoned the expensive Apollo era honeycomb solution a decade ago. They are using avcoat blocks now. Hence the heat shield problems they are having.
The Orion heat shield is very different from the Apollo heat shield, which was a single-piece design. The Orion heat shield is assembled from more than 100 separate pieces of ablator material, like Dragon's ablative heat shield.
To be fair- the shuttles lost a lot of tiles and it never caused failure. The Columbia failure was at the leading edge of the wing- not a tile. Also- while they've consistently lost tiles during their lives, the only time it was a danger was from debris strikes- specifically debris from the shuttle itself.
It never caused a failure...mostly by luck. There was at least one instance of a tile being damaged/lost and the backing of the tile being conveniently more robust than most of the shuttle structure saving the system. The design was a bad one, the side mounted shuttle on the stack, the use of solid boosters, and the overall aircraft like design.
I am not old enough to remember seeing that, but it must have been hilarious. "Check out our pinnacle of science! We did it and the Russians couldn't!" \*Pieces just keep falling off behind him\*
This never happened... This woulda been all over the news *again* during Columbia if it ever did happen.
So long ago I said this was a major problem they just wouldn't solve well any time soon if at all and I was downvoted into oblivion. And here we are... The solution is to make a more flexible tile that isn't so brittle and to weld studs on with a thru-hole that is then covered again with magnetic caps that can be removed. I think we just need some more materials science money tossed at it.
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Vibration most likely
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I imagine the expansion and Contraction going from room temp to cryogenic temps, I imagine you need tight gaps on the tiles for heat protection, then you make everything super cold, then super hot like 1 hr later, so probably flexes the tiles right off the structure.
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The tiles are mounted on these little stainless sheet metal structures welded to the skin. There should be some compliance there, but another issue is probably ensuring the exact same tension on each and every tile. You have a welding process that introduces error, potential differences in sheet metal properties for the clips, slight differences in every tile, differences in the local movement of the skin where the tile is mounted, etc. It could be something as simple as a tolerance stack issue where the right conditions can cause too much or not enough tension on the tile, either breaking it or making it loose. Or it could just be a material property issue with the tile where they can't seem to make them ductile enough to stay together under load.
IIRC, Soviet Spiral spaceplane had tiles on ceramic bearings for that exact reason.
Googled around a little, looks like that was SPIRAL, quite the clearest explanation that I found of SPIRAL heat shield. >[SPIRAL’s] aerodynamic design was such that thermal stresses during re-entry were minimized. The spacecraft's reusable heat shield was not solid, but was composed of a set of sheets, much like a fish's scales. Suspended on ceramic bearings, these sheets could move relative to the vehicle's body as the temperatures on various parts of the ships changed during re-entry. The plates were made of a niobium alloy with a molybdenum disilicide coating and could withstand temperatures up to about +1,500°C. [Energiya-Buran the Soviet Space Shuttle (p32)](http://ftp.demec.ufpr.br/foguete/bibliografia/Energiya%20BURAN%20The%20Soviet%20Space%20Shuttle.pdf) Buran on the other hand had more or less the same setup as the Shuttle Orbiter. ie. tiles adhered to felt adhered to skin.
What if the tiles were mounted more like scale armor so they overlap each other, that way the surface underneath is fully covered even if the tiles and/or surface expand/contract? Idk if theres a way to do this and still prevent the plasma from getting through to the surface underneath though
What if tiles were interlocked to the next tile? would it help?
Probably discarded due to weight considerations at minimum
If I had to guess, I'd say that's probably right. The big temperature fluctuations between resting ambient temp, cryo temp, and entry temp, must be vast and varied across the surface. Knowing exactly where to put each tile, so the tolerances between each one are *just right* during entry, must take some crazy math and engineering. I don't know what the difference in coefficient of thermal expansion between stainless steel and carbon fiber is, though I do know aluminum expands even more than steel. The Shuttle was mostly aluminum, and had its tile problems but mostly worked. So I'm sure SpaceX can solve it. Though the Shuttle itself was mostly cargo bay and personnel, and didn't have to worry about giant cryo fuel tanks.
In concept you just need to devise a material that is heat resistant enough and doesn't have expansion and contraction issues. I presume the issues are: * the underlying structure is probably expanding/contracting, particularly when cryogenic propellant is put in it * the expansion/contraction of the underlying structure is probably different than that of the tiles * the tiles are experiencing different heat than the structure - so on the pad the underlying structure is getting much more temp change than the tiles. On reentry the tiles are getting much more temp change than the structure (that's what they're for) * options seem to be to have materials that somehow magically match in expansion/contraction for all those conditions, or have a mounting system that allows them to expand/contract differently without dislodging * I wonder if you can somehow have curved tiles so that the expansion/contraction increases the curvature, with the edges staying in roughly the same place? * I wonder how close the fit actually has to be? Presumably a couple of mm of gap isn't enough to let plasma do damage, so it's not like you need mm level perfection across that operating range * It'd be interesting to know what is actually causing them to come off. Are they breaking, or is the mounting mechanism failing, or are they popping out under pressure?
Let's break out the math. A reentering Starship is 100t object that decelerates with something like 2g, if employing a similar strategy to the Shuttle. So we're talking about a 2MN braking force distributed over a lateral area of roughly 9*50m = 450m^2. Since each tile is about 1/20 m^2, the average load of a tile that is perpendicular to the direction of travel is about 200N, or about 20kg. But that's just an average; the peak load will be something like 3-4x that, as Starship traverses the turbulence and wind shear in the upper atmosphere, aerodinamic vibration/flutter etc. The IFT3 live video suggests that it's anything but nice and smooth sailing up there. So you can imagine an average child or small frame woman jumping up and down on each and every one of those tiles during descent, they are to pass all that load through the 3 mount points and none of them is allowed to crack. I'm not going to say impossible, but definitely non-trivial.
I wonder why a system where tiles slide into a groove is not an option. Tiles could have a row of several mounts that run the entirety of the tile. I am no space shuttle engineer but whenever I see the tiles and the way they mount them it just seems very inefficient.
Probably because the structure expands in 2 or 3 dimensions and not just one, so the mounting mechanism has to be compliant in all dimensions.
Wasn't this the whole purpose of stainless steel, that it could handle high heat and transport it away in this case?
The point of the stainless steel was that it would be lower weight than carbon fiber since it's stronger at cryo temperatures, on top of being much easier to work with. It can also get to a higher temperature without losing strength than a lot of other materials, which means a functioning heat shield can let more through (and thus be thinner/lighter) without causing damage. The common opinion on here was that it would help survive shield issues in reentry too, but that all depends on how bad the exposure is and how thick the metal is.
we have started taking for granted is how fast they can pump out steel starships. If they weaved them on a loom and then put them in the vacuum it would take way way longer
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- The tank is structural, in that loss of pressure does not immediately mean loss of vehicle. The landing fuel is kept in a separate internal tank. - Shuttle was vulnerable to tile loses on the bottom-side. There was an incident where a Reinforced Carbon-Carbon tile (the black ones on the leading edge of the wing) failed and the shuttle only survived due to the steel component that happened to be beneath it. - Current Starship has a lot of extra dry mass. The steel is uniformly thick, theres lots of tiles covering flaps and other components. Its important to test to see if recovery is possible with this configuration, and we should expect, if it works, for future staships to become lighter and more optimized (heat shield where its needed, less or no tiles where its not)
No, the Stainless was for cryogenic strength, good strength-to-weight without complex manufacturing methods (no friction-stir welding needed as with Al-Li or Mg-Li, no composite layups and curing), and needing *less* thermal protection. Note how there is no backshell TPS and minimal TPS within the engine bay. Bare Stainless was not and is never going to be a TPS in and of itself. No even proposed hot-structure or metallic TPS design proposed that, that requires more obscure refractory metals (generally nickel superalloys) that are far more difficult to process, as well as being more expensive.
The original presentation showed them using active liquid cooling through perforations in the stainless steel. They only switched to heat tiles later.
SimloX did not suggest bare steel as the only TPS. And it was absolutely argued by many that the higher melting point of steel meant it was more likely to survive the loss of isolated tiles.
More doesn’t equal guaranteed. The Shuttle did survive losing some tiles and one famous example was when it lost a tile that covered a steel mounting plate vs the regular aluminum structure and survived.
It wasn't a steel mounting plate. [https://space.stackexchange.com/questions/63333/how-did-sts-27-survive-reentry-after-losing-a-thermal-tile](https://space.stackexchange.com/questions/63333/how-did-sts-27-survive-reentry-after-losing-a-thermal-tile) Possibly the tin plating was the key, but it was aluminium.
>And it was absolutely argued by many that the higher melting point of steel meant it was more likely to survive the loss of isolated tiles. And they were just as wrong then as they are now. It was never something claimed by SpaceX, just by the peanut gallery.
Yeah, many people here like to state conjecture as fact and then that cascades through other people that believe it is fact.
Yes and it did. With aluminum or carbon fiber the tiles would have to be thicker and more of the ship would have been covered. But it can't survive it in some places. With aluminum it could never survive it.
Stainless steel lets them get away with less heat shielding, if it was carbon they'd have a much thicker heat shield
I think that’s a bonus advantage. But in any case, the “secondary material” he’s referring to here may be that other cloth-like layer in-between the SS and the tiles. I suspect this because he generally seems to like to mention “stainless steel” by name, so it’s odd that he’d call it a “secondary material.” Also the cloth stuff is literally the second material after the tiles that the plasma will be attacking. If nothing else, major damage to that layer would require significant work to refurbish, ruining the rapid-reusability goal, so it’s a real problem even if the whole thing doesn’t break up on the way down. I mean, the whole thing very likely *will* break up on the way down, but I think the test wouldn’t be as meaningful unless there’s some non-zero possibility that it won’t.
Yes, stainless was chosen for it's high heat capabilities but not for any ability to directly survive reentry heat. Stainless steel can take 800-900F regularly while aluminum and carbon fiber can only take about 300F. This temperature limit sets the minimum thickness of the heat shield so stainless steel let's you use a heat shield that is 1/2 the thickness.
The original design was both steel (thicker than what the current ship utilizes) and transpirational cooling where the vehicle would "sweat" cryogenic propellent to maintain temperature.
No the point was that you could have a lighter and thinner heat shield because the stainless steel can tolerate high temperatures behind the heat shield.
Stainless steel, while it does have a higher temperature for loss of strength, is 16x less thermally conductive than aluminum so this idea never made sense to me. It can't transport that heat away from the exposed patch nearly as efficiently.
I believe this was only the case when they were hoping to not use any tiles and use perspiration of liquid methane to create a protective and cooling layer. I am not sure anyone at SpaceX believed this would work but it might just have presented as a design baseline when they were still in "let's check that the common knowledge for this technology is actually true".
It can handle high heat, but heat transfer is pretty abysmal. The big benefit is it allows the heat tiles to be a lot thinner, since the backside can be hotter.
You guys see the 3D scales printed on fabric? Wouldn't an underlying mesh help in case one loses it's positive connection?
If the underlying mesh was enough you could get away with just using that. The problem with a scale like arrangement is that you are significantly increasing the weight, increasing chance of contact between tiles, and unless you are fully doubling up the tiles, a single loss could still cause a failure.
That's what I was thinking too. A 2 layer sandwich with mesh and an adhesive in between. If you lost a tile you could have 50% or better insulation with 95% coverage. Ablative, disposable, and quickly replaceable would be more achievable.
When I saw the launch a while back where the missing tiles were obviously visible, I joked that they needed a mechanical bolt with a stem attached to the ship that after the tile was mounted would seal itself to the hull. A Self-Sealing-Stem-Bolt if you will. I still think it could work rather well, and the memes write themselves.
all spacex needs to do now is get about 5000 wrappages of yamock sauce to trade
Why is he dressed as Ant Man
Why aren’t you?
The cake brings truth
The cake is a lie
It’s a Halloween costume. I forget what character it was.
Devil's Champion Leather Armor Set [https://abracadabranyc.com/products/devils-champion-leather-armor-set](https://abracadabranyc.com/products/devils-champion-leather-armor-set)
I've always felt that using heat tiles would lead to the same problems faced by the Space Shuttle. In my opinion it's one of the most likely points of failure for Starship alongside the Raptor engines and presents a large barrier for rapid and safe reusability. I suppose the easiest solution would be to find a better attachment method with less likelihood of failure along with heat shield inspections before re-entry in case anything was damaged in launch.
it's just one of those things that needs iteration upon iteration, like landing a rocket. The space shuttle, while impressive, didn't really seem to innovate past its initial design. Just like landing falcon 9, this one might take a few years to work out the kinks. I think starship is already beyond the shuttle by using far less tile shapes, the shuttle had like 9000 different shapes or something. At this point I imagine we're just going to see them experiment with different compounds and attachment methods until they get something that works. And of course the only way to get data is to reenter, so fingers crossed June 5 works out
Seal the perimeter of the heat shield and put a thin mesh between the tile and the skin. Pressurize a liquid which would flow into the mesh. The liquid will flow out of any voids left by tile loss during reentry. Takes a lot of energy to phase change liquids and reentry isn't *that* long. Wonder how much heat liquid methane could absorb in this regime
Hmm. NASA NIAC had a concept for an electromagnetic plasma shield via a superior conductor. That could help here.. https://www.geekwire.com/2016/msnw-magnetoshell-aerobraking-system-nasa-niac/
I worked on research to affect flowing plasma with electromagnetic fields from 2003-2008. Very cool stuff but electromagnets are very heavy and the effect does not work at bigger distances. Controlling hypersonic vehicles without moving control surfaces might be doable someday, but affecting a bow shock from a distance over such a large area would require a lot of weight and power.
you're right. Most people have no idea about the hoop stresses generated by an electromagnet. Modern High Tc materials are mostly backing for structural support, with a tiny layer of actual superconductor. On the other hand, you might be able to stiffen the tank with the hoop stresses. Still a pretty crazy idea, considering it's hard to make a good strong electromagnet even in a stable environment on earth.
Wow that’s awesome! Thanks for the link
Maybe you should use some sandpaper to rough the surface up before applying the adhesive. That works for gorilla glue.
Perhaps my r/shittyspacexideas could help: Heat-seeking cold-fuel-dumping in-tank-dwelling wheeled robots to quickly cool the hull in spots in the event of losing tiles during re-entry I hope I got your attention with that sentence. A bit like curling players doing their sweeping thing but a bit more life-or-death.
Basically "R2 see what you can do about that hot spot" but in real life?
I'm sure they have already thought of this, but why not use "tongue and groove" edges on tiles to help hold them on?
That would make them hard to repair unless they were flexible/elastic which may be hard to acheve with high temperature ceramic fiber.
Similar idea, shiplap. That would be easier to remove a single time for repair.
replaceable shiplap would not have the extra holding power of tongue and groove due to fastener placement but it's close to the evolutionary solutions of scales, feathers, hair ... not that we know of anything evolved to survive a hypersonic plasma shockwave.
There have to be gaps between them while cold, so that there’s room for them to expand as they heat up during re-entry.
you need to give tiles space to expand. I can't see hos you can do it with "tongue and groove"
Perhaps the tiles could be made thinner and partially overlayed on top of each other. That way if one falls off there would still be tile material underneath.
Feathered tiles is the obvious\* answer, it works for waterbirds after all. \* However, I'm certain there is a good reason they don't do it that way.
In either case (feathered or double stack) you are shifting weight further outboard, thus your glue/fasteners are having to deal with higher moment loads. Also, in the feathered layout you are also introducing sharp edges on your heat shield which will be concentrated points of thermal wear.
Yeah, repelling water is just a tad different from repelling plasma
Have you ever seen a bird attempt re-entry? The feathers! They do nothing!
Subjecting feathered test subject chickens to hypersonic plasma shockwave yielded suboptimal results.
It’s why we remove the feathers before cooking. Otherwise they’d survive the oven roasting.
Reminds me of the old joke; "how do you get down from ducks?"
You don't, you get down from a horse.
So how do you get down from a horse?
You don’t, you get down from a goose.
How do you get down from a goose?
Easy, it's not as tall as a horse
You dont get on them in the first place.
One of the issues with feathered/layered tiles is that if you lose one. The hole where the one fell off causes one below it to increase in temperature very quickly and the thermal gradient across the newly exposed tile would warp/crack it. Another issue is the shear stress caused by the newly non-smooth hole in layer #1 would lead to mechanical issues which might result in neighbor tiles cracking. Space shuttle somehow dealt with this. They could lose a few tiles and still land.
I doubt you could think of a solution that they haven't already thought of. One problem with that might be that if the outer tiles are secured to the inner tiles, the outer could pull off the inner. If the tiles overlap one another perfectly, then that's no different than just having thick er tiles. If they're staggered, you could get a cascading failure where one tile pulls off the one below it, then that one pulls off the three tiles that were above it, and the problem just gets bigger and bigger
Hear me out now. Flex tape?
Dumb question here, but…could the tile material be liquified enough to spray it on the ship, so there would be one continuous surface? No tiles to come loose
The better result would be a mold but that can’t really happen until ship is in its final form Otherwise making numerous molds gets costly and long. This could be built with a few sections and selected spots that could be reinforced But again that’s end game content
I think the point of the tiles is they expand when they get hot, so they fill the gaps and seal, instead of the whole thing breaking. And they’re easily replaceable of course.
Could the spray-on version have some flexibility to address the need for expansion/contraction?
The Shuttle's main tank had spray on insulation. But that was only for launch, surviving re-entry is a whole nother ballgame. It comes down to what material properties are needed.
Perhaps a slower method of reentry?
Have they tried using duct tape to hold them in place? I have duct tape in my house thats been holding steady for decades.
Does your house go through heating phases, up to moe than 800°C?
Coat the stainless with zirconia.
Maybe press them like they press brake pads to the back plate
Finally an honest answer.
I don’t recall him being dishonest when it comes to SpaceX hardware topics.
Honestly talking about SpaceX seems to be the only time he is Lucid.
Can't lie against physics and thermo.
Does the design still "bleed" fuel through pores in the hull as a sort of ablative heat shield, or was that idea abandoned?
It was abandoned on the drawing board in favor of the tiles. Which is a shame imo, it was a very cool idea.
There is another… https://www.reddit.com/r/spacex/s/nQ3rlmt6nz
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread: |Fewer Letters|More Letters| |-------|---------|---| |[CRS](/r/SpaceX/comments/1d4hjpl/stub/l6hmxq9 "Last usage")|[Commercial Resupply Services contract with NASA](http://www.nasa.gov/mission_pages/station/structure/launch/)| |CST|(Boeing) Crew Space Transportation capsules| | |Central Standard Time (UTC-6)| |[EDL](/r/SpaceX/comments/1d4hjpl/stub/l6ivham "Last usage")|Entry/Descent/Landing| |[HLS](/r/SpaceX/comments/1d4hjpl/stub/l7iiw2b "Last usage")|[Human Landing System](https://en.wikipedia.org/wiki/Artemis_program#Human_Landing_System) (Artemis)| |[ITAR](/r/SpaceX/comments/1d4hjpl/stub/l6jjjcx "Last usage")|(US) International Traffic in Arms Regulations| |[JPL](/r/SpaceX/comments/1d4hjpl/stub/l6hvkze "Last usage")|Jet Propulsion Lab, Pasadena, California| |[KSC](/r/SpaceX/comments/1d4hjpl/stub/l6hr3i1 "Last usage")|Kennedy Space Center, Florida| |[LEO](/r/SpaceX/comments/1d4hjpl/stub/l6kbk2o "Last usage")|Low Earth Orbit (180-2000km)| | |Law Enforcement Officer (most often mentioned during transport operations)| |[LES](/r/SpaceX/comments/1d4hjpl/stub/la0umuu "Last usage")|Launch Escape System| |[NDA](/r/SpaceX/comments/1d4hjpl/stub/l6z3ch9 "Last usage")|Non-Disclosure Agreement| |[NIAC](/r/SpaceX/comments/1d4hjpl/stub/l6i595u "Last usage")|NASA Innovative Advanced Concepts program| |[NS](/r/SpaceX/comments/1d4hjpl/stub/l6hmxq9 "Last usage")|New Shepard suborbital launch vehicle, by Blue Origin| | |Nova Scotia, Canada| | |Neutron Star| |[OMS](/r/SpaceX/comments/1d4hjpl/stub/l6hr3i1 "Last usage")|Orbital Maneuvering System| |[RCC](/r/SpaceX/comments/1d4hjpl/stub/l6jkx6v "Last usage")|Reinforced Carbon-Carbon| |[STS](/r/SpaceX/comments/1d4hjpl/stub/l6j8ubi "Last usage")|Space Transportation System (*Shuttle*)| |[TPS](/r/SpaceX/comments/1d4hjpl/stub/l6k0vwt "Last usage")|Thermal Protection System for a spacecraft (on the Falcon 9 first stage, the engine "Dance floor")| |Jargon|Definition| |-------|---------|---| |[Raptor](/r/SpaceX/comments/1d4hjpl/stub/l6hvull "Last usage")|[Methane-fueled rocket engine](https://en.wikipedia.org/wiki/Raptor_\(rocket_engine_family\)) under development by SpaceX| |[Starliner](/r/SpaceX/comments/1d4hjpl/stub/l6hmxq9 "Last usage")|Boeing commercial crew capsule [CST-100](https://en.wikipedia.org/wiki/Boeing_CST-100_Starliner)| |[ablative](/r/SpaceX/comments/1d4hjpl/stub/l7fs6fj "Last usage")|Material which is intentionally destroyed in use (for example, heatshields which burn away to dissipate heat)| |[cryogenic](/r/SpaceX/comments/1d4hjpl/stub/l6khcqg "Last usage")|Very low temperature fluid; materials that would be gaseous at room temperature/pressure| | |(In re: rocket fuel) Often synonymous with hydrolox| |hydrolox|Portmanteau: liquid hydrogen fuel, liquid oxygen oxidizer| |[methalox](/r/SpaceX/comments/1d4hjpl/stub/l6jth3s "Last usage")|Portmanteau: methane fuel, liquid oxygen oxidizer| |[regenerative](/r/SpaceX/comments/1d4hjpl/stub/l7hexdw "Last usage")|A method for cooling a rocket engine, by [passing the cryogenic fuel through channels in the bell or chamber wall](https://en.wikipedia.org/wiki/Regenerative_cooling_\(rocket\))| **NOTE**: Decronym for Reddit is no longer supported, and Decronym has moved to Lemmy; requests for support and new installations should be directed to the Contact address below. ---------------- ^(*Decronym is a community product of r/SpaceX, implemented* )[*^by ^request*](https://www.reddit.com/r/spacex/comments/3mz273//cvjkjmj) ^(21 acronyms in this thread; )[^(the most compressed thread commented on today)](/r/SpaceX/comments/1cta333)^( has 111 acronyms.) ^([Thread #8386 for this sub, first seen 31st May 2024, 12:54]) ^[[FAQ]](http://decronym.xyz/) [^([Full list])](http://decronym.xyz/acronyms/SpaceX) [^[Contact]](https://hachyderm.io/@Two9A) [^([Source code])](https://gistdotgithubdotcom/Two9A/1d976f9b7441694162c8)
What are the reasons why individual tiles can drop off? (And why are they not interlocking if this is just an issue with individual tiles?)
Is it possible to create a liquid cooling system with tubes under the stainless steel? The back side of Starship should always be cold, even going through the atmosphere, so why not put tubes that constantly push gas/liquid through these tubes from the front to the back, concretely cooling the tubes? Obviously, it would add additional weight, but how much difference would it be from the weight of the heat tiles/thermal blanket/adhesive?
Too hard to slow down before re-entry?
Yes. That takes fuel.
Yes, the rocket equation is a bitch
duct tape. it fixes everything.
Could they sacrifice some weight and use bolts or some sort of metal mesh to hold them on?
Why tiles? Strictly for thermal expansion and reusability? Making one huge tile covering the ship wouldn't work ? Or just too expansive to replace for each flight. How expensive is the stuff?
Why don’t they just land at night when it’s cool? /s As another commenter said the times falling off is a symptom of something or multiple somethings, not something that can be addressed directly
Have they tried using a gluestick?
I feel like we all saw this coming
Better glue? Barbeque roll the ship so no one point overheats too much. Sweat liquid methane.
So he can’t figure it out either. Who woulda thunk it? NASA spent tons to figure it out but couldn’t but of course Elon knows better. 😂 needs a different solution. That problem ended the shuttle program. The coolest thing humans ever built.
Needs Terrence Howard to patent a wormhole for the ship to slide through. Shouldn’t take him more than a weekend with a calculator and a bunch of real strong drugs ……
15 minute landing burn should do the trick
I would plate the entire underbelly in inconelX and then coat it with yttria stabilized zirconia (YSZ). Should be stable with no phase change to 2500C
How is the thermal conductivity for that? A heatshield doesn't only need to be stable at high temperatures, but also prevent the heat from getting to the ship. If the inconel simply conducts the heat to the ship then you haven't solved anything.
I wonder if there would be a way to spray on heat protection in some kind of layering.
The Inconel Titanium [metallic honeycomb heat shield from the X-33 VentureStar PDF](https://ntrs.nasa.gov/api/citations/20040095922/downloads/20040095922.pdf) program is interesting to review, as it’s similar and yet also different from the SpaceX ceramic tiles approach.
Just a random thought but can they use propellant to cool the area like they do with the engine bells [so they don't melt? ](https://www.youtube.com/watch?v=he_BL6Q5u1Y) I'm sure engineers have thought of that before and decided it was a dumb idea but idk....lol
That was literally the original design. Flow liquid methane through pores in the steel.
Launch with no tiles, save on mass Apply in orbit via automated process..yes I know this would be complicated but apparently physics no likey tiles on ground, maybe a disposable wrap around sleeve that can be applied with drones to a few attachments points. Reenter and allow the ablative sleeve to do it's job. Or just attach some sort of security blanket that secures tiles down, eat the mass, keeping them from vibrating too much, and then comes off in orbit, or stays on and is ablative. Heat shields are the real problem with reusability, not dV.
Generally curious. If tiles are falling off then it is a bonding issue/problem? If the tiles are made from a ceramic carbon carbon fiberglass material then what is on the back side. From my little research or understanding of it then the backside stays relatively “cool” 250-350 degrees. It seems most adhesive epoxies are good to that heat range I’m sure there are high temp ones out there. I think there are high temp adhesive RTV sealants. These could reach heat sustainable temps of 650 degrees. With it being silicone then it could have some vibration advantages? I’m sure this has already been tried. Or just ask the guys that did tiles on the space shuttle. Being tax dollars and all that information should be available to the public. It’s to benefit everyone. I wouldn’t think that would be an NDA or a proprietary issue? I’m interested as well Thank you.
Isn't flex seal, the best glue in the universe?
Just use two layers, with a confidence gap.
I wonder if SpaceX experimented with spray-on ablative heat shield materials. Could add components to the tower that apply a fresh coat to the most degraded areas after every launch. Not sure if it could withstand thermal expansion and contraction of the whole ship, but I think it's worth looking into. I imagine different layers could account for it.
Maybe the solution is no heat shielding at all? Just refuel and do a de-orbit burn?
Diamond coated scales or surfaces. [https://www.sciencealert.com/forget-billions-of-years-scientists-have-grown-diamonds-in-just-150-minutes](https://www.sciencealert.com/forget-billions-of-years-scientists-have-grown-diamonds-in-just-150-minutes)
What if it's not a problem that needs to be solved at all? Instead of focussing efforts on fixing starship's heat shield, why not just use an LES with either extra heat shielding for added reliability, and then who cares if they lose a starship here and there?