Shrapnel from the explosion may have damaged the other booster.

Musk’s Twitter feed is also uncharacteristically quiet ...

I could just imagine SN10 ducking and cringing with a “you want me to go next?? Nah,nah,nah.” Look.

From the video they only got one of the two needed Raptors to relight for landing. That caused the rotation to be late, and it didn’t have the thrust to cancel the inertia and stop at the vertical, never mind not having enough thrust to arrest the descent.

New rocket motor design, teething pains. It sounds like Elon may have been disappointed at the outcome, but they got a really good flight out of it. I wonder if there’s more to the story. At the very least it seems that they still have some fine tuning to do.

Note they drove their good crane a Loooong way away.
Maybe 10 isn't all that precious.

And ear protection.

Over the last 15+ years I've watched a lot of college engineering student groups do liquid rockets that the FAR site.

LOX has reasonable thermodynamics ie it does not get too fluffy if ia bit warm.
Based on some availible prize $ there was a big push in the last 5 years to do methane.

This increased the thermodynamic propellant conditioning problems by at least 4X.
Let Methane get even a little bit warm and it looses a lot of density.

Spacex is trying to run Methanes down a long pipe from a header tank up at the top/front of the rocket.
(The tanks are upfront for CG reasons) %#$@ going to be really hard to keep the methane cold and dense at the bottom of a long pipe.

IMHO they will need either active cryogenic cooling or active circulation AND excess tankage to make this happen.

The multiple short hot fire tests that ran last week or two killed two raptor....
I believe these were header tank start tests....

I'll make a wild speculation....
Spacex will build a fixture to hold a SNx on its side so they can test the landing restart under the expected acceleration orientation....without risking the vehicle...

Slowmo of the relight failure:

https://twitter.com/DJSnM/status/1356723874365276160

Actually the Methane (fuel) header tank is in the center of the vehicle, surrounded by the main propellant and oxidizer tanks. The single (shared) pipe that delivers fuel to the motors runs through the center of the LOx tank where it stays nice and cold. There is no difference in distance. The header tank at the top is the oxidizer header.



Methane is indeed picky about igniting. Spark ignited NG fueled engines operate in a very narrow mixture range. I would imagine that exothermic motors are similarly picky, however the Merlins have been lighting and relighting very reliably for a long time, so in my mind the problem is most likely related to fuel delivery. It's interesting that they got a better light off on SN8. It looked too as though the one Raptor that lit was burning well, with a good flame. The other simply wouldn't light. I agree that unless there's some clearly understood reason for this failure, they may need to test horizontally, but I don't see them doing it with a Starship. It would be much quicker and more practical to do it with a test rig that's built for the purpose. My guess is that they either already know what went wrong or have a pretty good idea. The worst case would be if there's no way to correct the issue without disassembling SN10.

They can always take SN11 or 12 or whatever is right now in the pipeline.

Me thinks they rolled out SN10 partially to show off their capabilities in rapid assembly, but also to free the space in assembly building for next one in line.

I'm wondering though if that speed isn't hindering progress - it's going to be hard to modify SN10 if test data show need for it.

They can always take SN11 or 12 or whatever is right now in the pipeline.

Me thinks they rolled out SN10 partially to show off their capabilities in rapid assembly, but also to free the space in assembly building for next one in line.

I'm wondering though if that speed isn't hindering progress - it's going to be hard to modify SN10 if test data show need for it.

Yeah, they can always use it to further test other areas of flight (20km? longer hovering?) and hope tweaks in software would let it land.

On the other hand if the probability of crash is 1 they might want to at least save the raptors and other internal hardware even if the shell is toast... or add a chute and test that as an emergency backup - do the flip at 5000ft and pull the red handle.

Yeah, they can always use it to further test other areas of flight (20km? longer hovering?) and hope tweaks in software would let it land.

On the other hand if the probability of crash is 1 they might want to at least save the raptors and other internal hardware even if the shell is toast... or add a chute and test that as an emergency backup - do the flip at 5000ft and pull the red handle.

This thread reminds me that on the internet, everyone is an expert.

I’m not an expert but my common sense does wonder why they don’t start all three briefly and then shut one down again if they all start or keep the two that start if only two fire up.

It may be the case that this is just testing and in the full up build they’ll have enough mass left on landing that the difference between too much thrust and not enough thrust is within the throttle range of both n engines they plan to start and n-1 or n-2 engines in case one or two don’t come back to life.

I also am not an expert, but if I were considering a space tourism adventure I would not want to be in a landing vehicle where the required engines did not ALL light off RELIABLY. Every time! I would be a lot less interested if they have to try to light 3 engines to get one to light reliably...

I also am not an expert, but if I were considering a space tourism adventure I would not want to be in a landing vehicle where the required engines did not ALL light off RELIABLY. Every time! I would be a lot less interested if they have to try to light 3 engines to get one to light reliably...