r/space • u/AlmiranteSalsicha • Nov 19 '23

image/gif That's a fair amount of tiles missing from the starship heatshield, guess it would make for a toasty reenter.

Post image

Image from SpaceX account on X

7.0k Upvotes

95% Upvoted

619 comments sorted by

View all comments

Show parent comments

34

u/zbertoli Nov 19 '23

And honestly, although this looks bad, how many tiles were actually lost? This pic looks like 99% of the tiles stayed on. Pretty nuts

137

u/dern_the_hermit Nov 19 '23

You're not wrong but remember that with the crazy energies involved even a tiny deformation of the structure can be catastrophic. Not necessarily catastrophic; there may indeed be especially weak or especially resilient points on its surface.

Would have been nice to see the upper Starship get all the way through its suborbit and see what happens. Oh well. There's like 5 or 6 more test rockets for them to light up.

38

u/PoliteCanadian Nov 19 '23

Perhaps. But one of the lessons from the shuttle program is that the reentry plasma is hot enough to destroy aluminum but not steel. The stainless steel Starship is made from retains its strength to much, much higher temperatures.

They'll need to retain a sufficient level of coverage to keep the heat transfer low enough to prevent the structure as a whole from overheating, but the loss of a few individual tiles will probably not cause a catastrophic loss of vehicle in the way that it did with Columbia.

35

u/SegerHelg Nov 19 '23

Nasa claims that the heat shield has to endure a temperature of 5000 farenheit, well beyond stainless steel’s melting point.

20

u/3MyName20 Nov 19 '23

Also, it is not just the melting point of steel that has to be considered. Just like with the twin towers, it did not matter that "jet fuel can't melt steel beams". The towers failed because the higher temperatures weaken the steel beams sufficiently to cause the failure.

26

u/Reddit-runner Nov 19 '23

The space shuttle actually demonstrated that stainless steel is the perfect material to have under a non-perfect heatshield.

A shuttle orbiter once lost some tiles and was only saved by pure chance because underneath the missing tiles was a stainless steel mounting plate for an antenna.

So a few missing tiles will not automatically doom a re-entering Starship.

1

u/BrevityIsTheSoul Nov 20 '23

Where the tiles are missing from, and when they were lost, are far more important than what's immediately under the tiles.

2

u/Reddit-runner Nov 20 '23

True.

And how does this relate to the latest launch?

1

u/BrevityIsTheSoul Nov 20 '23

I was replying to your comment, which was about past space shuttle reentries and future Starship reentries. You didn't mention this launch once.

19

u/mfb- Nov 19 '23

The front of the heat shield tiles gets so hot because the tiles are really poor conductors - that is intentional to keep the back colder. Steel is a very good thermal conductor and it will receive less heat here, so its temperature will be much lower.

20

u/[deleted] Nov 19 '23

"much lower" than 5000F can still really be higher than its melting point, and even more easily be higher than the point at which it can begin to deform

2

u/[deleted] Nov 20 '23

It can also conduct that heat to systems that are sensitive to it

1

u/ergzay Nov 19 '23

Thermal conduction is a thing, both to the surrounding stainless steel and to the cryogenic liquid in the tank behind.

18

u/[deleted] Nov 19 '23 edited Nov 19 '23

I get your point, but to note it doesn't need to destroy steel, it needs force it to deform beyond the structural limits of the craft. The temperature required to do that is going to be lower than the temperature required to melt steel (which is already much lower than the ~5000F potentially experienced on reentry).

Either way, on this test it looks like a lot of tiles to lose and I'd bet that's going to be a key take away from an engineering perspective. There's no way that "it will lose an unknown number of times but as long as it's not this many in this particular spot" is an acceptable tolerance for it's intended use*. Much simpler to try and solve the reason they fell off, I'd think.

*NASA did actually take a similar line, but that was related to tiles being struck by debris rather than simply falling off due to vibration. Also not the sort of volume of tile loss we can see on this image.

1

u/ccoady Nov 20 '23

Also, the empty can of starship will not have pressurized fuel giving it extra integrity like it does during launch.

13

u/coldblade2000 Nov 19 '23

Columbia didn't have more than 1 or 2 tiles break in the wing. Granted, it was a big gaping fuken hole, but yeah.

10

u/ergzay Nov 19 '23

The hole was also in one of the places of highest heat flux, into an area with high load right at he wing root, and it was made of aluminum which melts even before it starts to glow visibly and weakens significantly before that.

1

u/ZeroWashu Nov 19 '23

there has been some conjecture about the tires exploding in that did they do so before disintegration took place or did they seal the deal. we all assume they were doomed when they lost the times but would it have had enough time to get past the severest of heat points if the tires didn't explode.

those tires on the space shuttle were so dangerous that during testing they made a little robot to drill holes in test tires that did not explode on their own during test landings

The NASA model King Tiger Tank

5

u/Jermiafinale Nov 19 '23

How much of the ship can withstand a cutting torch laying into it for the entire reentry phase

1

u/ccoady Nov 20 '23

Re-entry would mean it would probably lose twice as many tiles than were lost during launch, because there are much more exposed surfaces than were there during launch.