SpaceX Starship : First Flight : Starbase, TX : 20 April 2023 - DISCUSSION

[meekGee]

No, because they will be crossing back into Hawaii, which is the same day as the rest of the US. If they were splashing it down in the lagoon on Kwaj, it would have worked out though!

Foiled by geoTemporalPolitics!

[alugobi]

If it was a pressurization issue, does it make sense that it would be a GSE valve?

Could be.  They have to close and isolate all the fill lines back to the tank farm in order to prevent a burn back from a 'splody rocket.

[woods170]

Does SpaceX make their own valves in-house, or do they procure them from somebody else?

Vehicle side valves are all built in-house. Non-industry standard GSE-side valves are also built in-house or by their favourite contractor to specs provided by SpaceX. But stuff like ground valves at the tank farm are all industry-standard stuff and procured commercially.

[woods170]

Well, I thought they should do a WDR before proceeding to launch ... but I actually DON'T feel vindicated by this. But for the valve issue, everything went flawlessly and they nearly were ready to go. Was probably a low probability of going all the way to hold-down release, but prepping everything for liftoff seems reasonable. They did the truest possible rehearsal and will be more likely to be ready to go next time.

quite the irony that this scrub was due to faulty valves as well  People were chirping SLS for it left right and center lol

Wasn't a faulty valve. It was a perfectly normally working valve that got frozen. One of the SLS scrubs however involved a valve on the ICPS that was actually kaput (as in broken, defective, etc), and had to be replaced by a non-kaput one.

[chopsticks]

Yusaku Maezawa (of DearMoon) gave more information about the valve issue:

燃料タンクにヘリウムガスを装填するバルブが冷却によって凍ってしまい、ガスの装填が上手くいかなかったとのこと。

The valve that charges the helium gas to the fuel tank was frozen due to cooling, and gas charging did not go well.

https://twitter.com/yousuck2020/status/1647983047676153858

Does this mean that the methane tank is pressed with helium instead using autogenous pressurization?

Or maybe there are helium COPVs inside the methane tank that are used for Raptor spinup?

[Fireworking]

Had this been a standalone WDR, we probably wouldn't have heard about the frozen valve. Maybe something similar happened on the previous WDR, but due to the fact that it wasn't launching, they could go through with the test.

It does seem strange that it froze this time, even though they have done fillups on the booster multiple times. It's possible they treated this more like a WDR from the start, and if everything went well they would launch. I'm just speculating here.

It's definitely encouraging that nothing went wrong aside from the valve, and that we were able to make it all the way to T-40s.

[sanman]

But is the helium being used cryogenic? Why would the valve be vulnerable to cooling? Or is it somehow in contact with the other cryo-propellants?

[Slothman]

But is the helium being used cryogenic? Why would the valve be vulnerable to cooling? Or is it somehow in contact with the other cryo-propellants?

I suppose the valve connects to the propellant tank(s), which were more or less full at the time and frosty to the top (minus some of the domes) and full of cryo liquids.

[Prettz]

I thought it was established that SH/SS used no helium.

[Comga]

Well, I thought they should do a WDR before proceeding to launch ... but I actually DON'T feel vindicated by this. But for the valve issue, everything went flawlessly and they nearly were ready to go. Was probably a low probability of going all the way to hold-down release, but prepping everything for liftoff seems reasonable. They did the truest possible rehearsal and will be more likely to be ready to go next time.

They loaded prop at the coldest time of the day.

My speculation: maybe the extra heat would have stopped it from freezing up.

Have they ever done a WDR/similar before dawn?

Cheers, Martin

The temperature differential between the hottest time of day vs the coldest would hardly have an impact on this IMO due to the far greater temperature differential between ambient and cryogenic.

For LOX, it's what, -200C or so? So if it was 15C this morning (probably wasn't that cold) and it gets up to 30C during the day, that's only 15 degrees of difference. To me, whether the LOX is -215 or -230 from ambient seems like it wouldn't make a difference on whether a valve freezes or not, but maybe they are that picky.. IDK

Agreed  WDK (We don’t know)
But there could be a counterintuitive link.
The difference in temperature differences would be small, as said.
But warmer air will carry more moisture.
15 C of difference means 2.8X in water carrying capacity. (2^(dT/10K) )
Ice buildup could be faster.

We can only hope that SpaceX gives us some additional information.
And now they have courtesy of Maezawa.

[envy887]

I thought it was established that SH/SS used no helium.

They may not have any stored on board, but that doesn't preclude using ground-supplied helium to pressurize the tanks while on the pad.

Helium is really nice for this because it doesn't condense into subcooled liquid propellants. And the onboard autogenous system does not supply any hot pressurants before engine ignition.

[Prettz]

They may not have any stored on board, but that doesn't preclude using ground-supplied helium to pressurize the tanks while on the pad.

Hopefully very little, otherwise that's gonna add up.

Helium is really nice for this because it doesn't condense into subcooled liquid propellants. And the onboard autogenous system does not supply any hot pressurants before engine ignition.

Sure, but the ground could supply anything needed. I thought they'd figured something out already.

[Alberto-Girardi]

I don't want to be the spaceX lawyer here, but I would note that the fueling was perfect, as far as we know. I would think this is significant given it seemed as good as today during the WDR of January.
I don't think that the issue we saw today could have happened during that WDR, because we saw them doing a booster test (maybe a WDR) a few days ago. If any issue was known they would probably have been able to test for it.

My completely speculative take: this is a kind of failure that has some probability to happen, maybe low, it doesn't seem to be a inherent issue with the vehicle design.

[Alberto-Girardi]

...

Helium is really nice for this because it doesn't condense into subcooled liquid propellants. And the onboard autogenous system does not supply any hot pressurants before engine ignition.

Sure, but the ground could supply anything needed. I thought they'd figured something out already.

They have a line supplying the booster with gas oxygen and CH4, the so called "prepress", but idk if they are to be used during the propellant loading to fill some internal storage COPV.

[Michel Van]

Post deleted on Order of Moderator

[SpunkyEnigma]

Felt like 3-4 times as many people than there were for SN8.  Though that was Covid times.

Lotsa people walking the beach down from the hotels

[Alberto-Girardi]

Also, what can we say about this flight being somewhat ignored? AFAIR the spaceX stream peaked at ~0.5 M viewers. The launch was scrubbed only at T- 9 minutes, well close to launch.

For reference Falcon Heavy test flight was watched by 2.3 M live (now youtube lists 33M because of the replays).

Counting the biggest "unofficial streams" we have 240k watching NSF and ~100k with Everyday Astronaut ( I am being triple counted here).

This is strange given the growth of the space community in this 5 years.

edit: this is about the web coverage, I am not contradicting what SpunkyEnigma said, I don't know about that.

[cplchanb]

Well, I thought they should do a WDR before proceeding to launch ... but I actually DON'T feel vindicated by this. But for the valve issue, everything went flawlessly and they nearly were ready to go. Was probably a low probability of going all the way to hold-down release, but prepping everything for liftoff seems reasonable. They did the truest possible rehearsal and will be more likely to be ready to go next time.

quite the irony that this scrub was due to faulty valves as well  People were chirping SLS for it left right and center lol

Wasn't a faulty valve. It was a perfectly normally working valve that got frozen. One of the SLS scrubs however involved a valve on the ICPS that was actually kaput (as in broken, defective, etc), and had to be replaced by a non-kaput one.

well regardless of whether its actually broken or frozen shut, the fact is that it failed to operate when commanded which means theres a fault to it, hence a faulty valve.
then again we shall see in the next 48hrs what they will do to address this. will they also replace the valve?? who knows...

[ugordan]

well regardless of whether its actually broken or frozen shut, the fact is that it failed to operate when commanded which means theres a fault to it, hence a faulty valve.

So let me get this straight: you bring the valve outside its designed operating environment (by freezing it by an outside factor) and that makes it faulty?

Okay.

If a water pipe bursts because ice formed inside it, was the pipe at fault or was it whatever let the water get frozen inside it?

[Herb Schaltegger]

well regardless of whether its actually broken or frozen shut, the fact is that it failed to operate when commanded which means theres a fault to it, hence a faulty valve.

No engineer in the world, especially an aerospace engineer, would describe a frozen valve as “faulty” absent a physical fault preventing actuation (a condition for which we have zero evidence).