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#2351 2026-08-01 14:14:55
- tahanson43206
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Re: Starship is Go...
GW Johnson wrote a paper on what it will take to return from Mars and attempt to slow down in the atmosphere.
https://www.dropbox.com/scl/fi/9y7wx2hf … 2x930&dl=0
The title is "A Look at Interplanetary Returns vs Cislunar Returns"
(th)
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#2352 2026-08-01 22:55:02
- RobertDyck
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Re: Starship is Go...
I appears that SpaceX is in the process of recovering the intact starship and is towing it to Australia. Musk released a statement yesterday to that effect.
Yea! When I saw it float. I thought that should be done. Engineers will get a much better read by getting their hands on it
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#2353 2026-08-01 23:05:56
- RobertDyck
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Re: Starship is Go...
For anyone considering a winged entry vehicle. I recommend a lifting body like Dream Chaser. Lighter weight than a fuselage and delta wing. Glide distance isn't as great, but enough. Shuttle was supposed to be a lifting body. But military wanted to launch spy satellites from Shuttle into polar orbit. NASA had made arrangements to land Shuttle at airports around the world, so it could reenter the atmosphere at any point and land safely. That worked for inclined orbits, but there were no airports at the poles able to land Shuttle. So they needed to extend glide distance far enough to reach one. Just don't launch your large reusable spacecraft into polar orbit.
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#2354 2026-08-02 04:42:48
- SpaceNut
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Re: Starship is Go...
The issue is the launch of everything in the same vehicle with cargo tonnage pushing the 1 time launching into a monster and then when you need to protect for that vehicle carrying crew it now goes into that one problem of getting rid of heat no matter where its going.
Winglets, fins and rear of the vehicle are not true glider to lift but are just for short steering or to correct rotation axis so that the body is aligned for the atmospheric braking on the bodies greater heat shielding surface.
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#2355 2026-08-02 17:23:44
Re: Starship is Go...
…
The quote from the former NASA scientists is more definitive in this article:
Experts warn current Starship heat shield tech is a “dead end” for rapid reuse.
NASA has not made substantial investments in thermal protection research for decades.
ERIC BERGER – JUL 27, 2026 2:34 PM |
https://arstechnica.com/space/2026/07/d … -to-crack/I think we should reexamine giving Starship wings that result in such an ultra low ballistic coefficient that no heat shield is required at all. We had that discussion here, GW:
GW, your and Dr. Akin’s separate analyses both suggesting 800°C peak temperature gives confidence it is valid. The problem is there is a discrepancy with an actual LEO reentry experiment at low ballistic coefficient. The experiment was called LOFTID and used an inflatable heat shield:
What was the ballistic coefficient of the LOFTID demonstrator and what was peak temperature?
The ballistic coefficient of the Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) demonstrator was 24.7 kg/m², and the outer surface of its heatshield reached a peak temperature of approximately 1,500°C (2,700°F) during atmospheric reentry. [1, 2]
Key Flight Demonstration Metrics
NASA's LOFTID Mission successfully validated hypersonic inflatable aerodynamic decelerator (HIAD) tech with the following flight data: [1, 2, 3, 4]
* Entry Mass: 1,100 kg
*
* Aeroshell Diameter: 6 meters (fully inflated)
*
* Peak Heat Flux: ~40 W/cm²
*
* Peak Deceleration: 9.5 g
*
* Entry Velocity: 8 km/s (approx. Mach 30) [1, 2, 3, 4]
*
The vehicle's second-generation flexible thermal protection system (F-TPS) featured an exterior ceramic fiber cloth designed to survive environmental limits up to 1,600°C (2,900°F), comfortably protecting the structural inflatable rings from the peak heating experienced during the test. [1, 2]
If you would like to explore this topic further, I can provide more details on the layer composition of the flexible thermal protection system or compare LOFTID's metrics to previous suborbital tests like IRVE-3. Let me know what you would prefer! [, 2]
https://www.google.com/search?q=What+wa … emperature
The ballistic coefficient of ~25 kg/m² for a 6 m wide decelerator was in the range comparable to both yours and Dr. Akin’s. But the peak temperature was nearly twice as high at 1,500°C.
The shape was different in being a flattened cone, while yours and Dr. Akins was a portion of a sphere but I wouldn’t think the difference would be that big.
NASA Successfully Tests LOFTID Inflatable Heat Shield.
https://www.youtube.com/watch?v=9mM1JIPY4Mw
Bob Clark
Last edited by RGClark (2026-08-02 17:53:16)
Old Space rule of acquisition (with a nod to Star Trek - the Next Generation):
“Anything worth doing is worth doing for a billion dollars.”
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#2356 2026-08-04 10:04:23
- Oldfart1939
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Re: Starship is Go...
There is a new WhatAboutIt episode which is now available online at YouTube. Felix discusses the heat shield of S.40 issues in detail.
https://www.youtube.com/watch?v=zKAtEutivr4
Last edited by Oldfart1939 (2026-08-04 10:05:15)
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#2357 2026-08-04 13:10:14
- Void
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Re: Starship is Go...
Very nice OF.
I think something that is missed in the conversation is that unlike the Space Shuttle a failed heat shield does not kill Astronauts, as there will not be any on board for commercial flights, at least not for a long time.
And I took a look; it sounds like there have been burn-throughs of the Stainless Steel where tiles were deliberately left off. I am not 100% sure but it may be possible that they could still recover such a ship, at least by catching.
Burn through apparently is not a actual hole but strongly scorched Stainless Steel. I note that for the Space Shuttle that would be deadly if only an Aluminum Alloy was under the tiles.
Quote:
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Yes — SpaceX has already flown Starship missions where the heat shield was intentionally removed or damaged, exposing the stainless steel to extreme reentry heat, and in some cases the steel was scorched or “burned through” in test scenarios.In October 2025, SpaceX conducted an uncrewed test flight with thousands of heat-shield tiles removed from critical sections of the upper stage, leaving parts of the vehicle’s stainless-steel structure bare and exposed to temperatures above 1,400°C during atmospheric reentry www.visaverge.com. This was a “deliberate high-fidelity failure study” to observe how local failures spread and whether the steel could withstand direct plasma heating. The mission was successful in other respects, but the exposed steel was visibly damaged.
Earlier, on Flight 10 in September 2025, SpaceX used metal test tiles and left gaps in the heat shield, creating bright orange streaks from oxidized test tiles and white patches where insulation replaced lost tiles Interesting Engineering. Post-flight photos showed scorched steel, dents, and burn marks on the body and flaps, with some flaps even glowing red-hot during descent Interesting Engineering. These were not full structural failures, but clear evidence of the steel being heated to extreme levels.
In interviews, engineers confirmed that in some missing-tile tests, a single-layer ablative insulation burned through to at least scorch the underlying steel, while a double-layer did not NASASpaceFlight.com. This means that in certain configurations, the stainless steel was indeed exposed to the point of visible damage, though not necessarily melted.
Summary:
Yes, Starship has had heat shield burns that exposed stainless steel to >1,400°C.
These were deliberate test flights to study thermal protection limits.
Damage included scorched steel, chipped tiles, and panel gaps in operational flights AOL+1.
In some test cases, single-layer insulation burned through to the steel NASASpaceFlight.com.
The steel has survived these tests, but the results are driving design changes to prevent burn-through in future flights.
So, such a ship landed or tower caught, might still allow many of the valuable parts to be reused such as Engines and electric motors and steering linkages, and Avionics.
Perhaps the Hull could not be trusted again to hold pressurized propellants.
Ending Pending 
I note that they said that a double layer of ablative heat shield might protect the Stainless Steel. This would be an interesting application for sending one-way ships to Mars with cargo, I think. Might have its own values.
Ending Pending
Last edited by Void (2026-08-04 18:41:52)
Be careful what you wish for.
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#2358 Yesterday 12:46:45
- GW Johnson
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Re: Starship is Go...
For RG Clark re: post 2355 --
Bob, I worked out a model from the data in your posting about the LOFTID test, and got something fairly representative of their blunted cone shape and size and ballistic coefficient. And yes, the shape makes a difference: blunted cones are what has been used at Mars for decades to minimize plasma radiation heating, and those drag coefficients are near 1.7. Spherical radius-type blunt heat shields have been used at Earth where plasma radiation is not as severe, and have lower drag coefficients, nearer 1.4. For the same size and mass, that is a big difference in ballistic coefficient, and thus in peak heating, as well as how deep into the atmosphere it penetrates before slowing.
I got numbers more or less similar to those in the article you linked and quoted, except I got nearer only 6 gees at peak deceleration, and that article indicates something over 9 gees. I used an average 2 degrees below horizontal, they may have come in a bit steeper than that, although steeper does drive up heating, too.
The temperature I got for a re-radiating heat shield with no ablation is close to what they seem to say in the article. I must be somewhere in the ballpark with my little model. However, when I spread heating rates around the vehicle, I got surface temperatures seemingly too high for inflatable fabrics to survive. I think they said something about insulating the inflatables with ceramic fabrics. The problem with equilibrium temperature estimates is that they are extraordinarily affected by the thermal emissivity that you use.
My point: the picture a lot of people share, that you only need protection on the windward side, is false. Even the wake zone sees the same super-high effective plasma temperatures that the windward side sees right behind the bow shock. It's just that the effective heat transfer coefficients are drastically lower. That is why Apollo's (and Orion's) lateral sides also had ablative coatings. The higher speed drove that. Bare superalloy skins survived on Mercury and Gemini, but only because entry speeds were lower.
The inflatables at the lower speeds will need wake zone heat protection, because the inflatable materials have lower max service temperatures than superalloys. By far.
GW
Last edited by GW Johnson (Yesterday 12:48:27)
GW Johnson
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"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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#2359 Yesterday 12:56:09
- GW Johnson
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Re: Starship is Go...
For void re posting 2357: you have to be very careful about risking a burn-through into a propellant tank, for 2 reasons, either of which could be fatal to the vehicle. (1) The pressurization level of the tank may be part-and-parcel of the strength of the tank to resist crushing by the wind-stream pressures. (2) The propellant feed to the engines' turbopumps, and indeed even the boiloff speed of the propellant inside the tank, depends upon maintaining the right amount of tank pressurization.
It would be into the cargo bay, the engine bay, or the aerosurfaces themselves, that they would have risked burn-throughs by leaving off a tile here or there. Those spaces are already unpressurized to begin with.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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#2360 Yesterday 17:59:40
- SpaceNut
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Re: Starship is Go...
never forget what happen to the shuttle as caused by the blow through of an o-ring into the ET....
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#2361 Yesterday 18:35:59
- GW Johnson
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Re: Starship is Go...
Harold:
No, I never forget. That was a bad joint design to begin with. I think we have beat that to death before. You DO NOT DO 2 O-RINGS in a solid joint! You do only 1! If it holds at 20-30 psia, it will hold at 2000-plus psi.
Ask me sometime about the Tarter-Terrier gas generator canister. Same stupid problem. Just embodied differently.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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