Comment by Laremere
2 days ago
Summary from my watch:
- Launch roughly on time, after a scrub yesterday. (Sounds like the scrub was due to ground equipment, most notably the water system.)
- Initial ascent was good, but then one engine on the booster went out.
- Relight of the booster's engines after stage separation for the boost back burn failed. Engines did light again for a landing burn, but seems to have hit the water harder than expected and was very off target.
- Starship lost one engine shortly after stage sep. Turned into an unintentional test of engine out capability. It made it to space.
- Some weird motion and lots of off-gassing after engine cut-off, with uncertainty about if it actually got a good orbital(ish) insertion. Seems to have been benign, with the motion being a weird slow flip to the orientation for payload deployment.
- Test deployment of dummy payloads was successful, including a couple with cameras to look back at Starship.
- An in space engine relight test was skipped, presumably due to the issues during launch.
- Re-entry to over the Indian Ocean seemed to go really well. Nothing obviously burning or falling off. The amazing views of the plasma during re-entry, something never seen live before starship, are now routine.
- Starship did a maneuver to simulate how they'll have to go out over the gulf and back to the landing site.
- Nailed the target, evidenced by views from drones and buoys. Soft landing before falling over and giving us a big (expected) boom.
As far as overall progress from previous test flights goes, they're at least treading water while making many large changes. I think they were hoping to try for a tower catch and actually going orbital for next flight, but I highly doubt that now. The boostback burn failing was the largest failure, with the engine failure on Starship being a close second. Good performance despite engine out seems to be an unintentional success.
Nice work by SpaceX engineering.
Good summary. The booster appeared to hit the water at 1400 km/h (a bit under 900 mph) so not really survivable :-). Engine out on ship seems to left them with just enough fuel to land but not enough to do the hover thing (simulates being caught by chopsticks). They notched it down to two engines (vs planned 3) on the landing it seems?
Basically if they can figure out the engine issues, it looks like they should be able to do a full end to end flight. That's reasonable progress. Given the IPO this was a pretty important flight and I don't think they hurt it (like blowing up on the launch pad would have). So their one step closer it seems.
Landing on two engines was the plan.
V3 Raptors are too powerful, they no longer need three engines to land. They are only going with two from here on out.
So I think it’s unlikely that they altered any aspect of the landing test due to lighting only two engines… as they was the plan anyway.
Hmm, I've seen data that landing the booster on 2 engines was the plan, but hadn't seem similar things about Starship. The difference is the chamber pressure you need in the individual engines. Lower chamber pressure has, in the past, been easier to modulate for precise control. Do you know if they've done any white papers or patents on V3's flow aeronautics?
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Is there videos of booster crash?
Not that I have been able to find, the 1400 km/h number comes from the telemetry on the video just before it contacted the water. Presumably one could estimate the return point if you had access to the telemetry and perhaps a platform in the Gulf might have eyes on it. Depends on how far east it got.
I doubt it since many of the booster engines didn't seem to relight, the location of touchdown wasn't near any pre-positioned cameras (if there were any).
Good summary. I was pleasantly surprised that they nailed the re-entry target even after the ascent engine problems.
The re-entry itself looks amazingly smooth compared to V2. TBD whether it's good enough for re-usability (much less rapid re-usability).
But Flight 12 was definitely forward progress.
It looks like the ships software did a phenomenal job compensating by adding that much longer Second stage burn time. It was also very cool to see the sea levels vector to compensate for the thrust asymmetry. All and all that ship is look really realllllly good. Seems like they just need to add some mass to Raptor to reduce the tendency to tear itself apart..
1 out of 33 failing hardly seems like a tendency - probably some minor issue. Relight was likely an issue with new downcomer that was supposed to improve boost back engine feeds for its flip maneuver - that seems to need work.
The videos were incredible. My favorite part was watching the booster flip in such clarity. Normally we don't get full view of it, let alone 4k.
Scott Manley pointed out that it seemed to flip in the wrong direction, with one of the grid fins passing through the plume and inducing a roll. Will be interesting to hear more about that.
The videos are great!, but the rest of it is never going to work lol, just never. Even without a rethink about how to get heavy payloads to another planet this is still good entertainment.
why won't it ever work?
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While we're downing this I'd like to add I think the "I've written X in Rust" posts are also cringe :D
SpaceX does an excellent job at videography. Sad that Nasa flew its Artemis mission with potato cameras.
SpaceX probably spends a lot of money on marketing/public relations creating great media. I'm guessing NASA's on a shoestring budget for that kind of thing.
SLS was far from a shoestring budget and both NASA and Boeing/Northrop/etc have equally strong incentive to provide solid coverage for the public to keep the jobs program going.
SpaceX has much better infrastructure for video with their satellites and are just generally more competent at production
One of SpaceX’s founding reasons was to promote STEM and they continue to do that with their video productions.
Hey, we have everyone watching, our funding might in part depend on interest and awe…
Not just space-potatoes… but missed the separation shot on the live feed. How in the hell!?
I think the ship really punted the booster during stage separation. And caused the boost back failure from sloshing.
Also I think Ship now has methane thrusters on it. They were operating with a clean blue flame in short purposeful bursts.
If we look at the venting from the propellant tank (around T+16:15) it looks thick white closer to the vent, becoming more transparent and blue as it expands. That's just sunlight scattering on the particles and density fluctuations in the flow.
A good cold gas thruster produces a lower density, more expanded flow, which looks blue for the same the reason the sky looks blue.
One can compare this to the exhaust from various Falcon-9 engines and thrusters when it is illuminated by the sun on the backdrop of the night sky: https://youtu.be/JRzZl_nq6fk?t=193
From what I've read there was "unintentional mixing of fuel and oxidizer" which caused a fire in the engine section, so the engines automatically shut down. I don't thing we have official word yet, though.
I'm concerned about the cracking clearly visible on the heat shield tiles. It doesn't bode well for rapid reusability.
I thought the tiles were designed for easy replacement, so not a big concern with replacing cracked ones.
The tiles ablate. The shuttle returned from every mission with missing tiles.
Shuttle's tiles not being durable as hoped is what killed it's turnaround time.
The problem was never solved and turned what was supposed to be a few days into weeks or months. Every mission the shuttle had to go back into the assembly building and have all tiles inspected and potentially replaced.
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The tiles are not supposed to ablate - they're supposed to be ~fully reusable. That said I think it's plausible that the much higher iteration speed and lack of a need for human-rating (at least during reentry, for now) will allow for more success than the space shuttle saw with its similar approach.
Starship’s tiles are not designed to ablate. They are intended to last multiple flights.
The shuttle required long expensive refurbishment after each flight.
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Well, every mission that it returned from it had missing tiles. That is not the same thing as returning from every mission.
That wasn’t cracking.
I mean ... step 1 is probably fixing the part where it lands in the ocean, falls over and explodes. Once they've done that and can get their hands on the tiles I'm guessing they can continue to iterate there until they get a more easily reusable design.
That part was intentional
Dang, a random HN user solving all the world's problems yet again, what would humanity do without you random HN guy?
Thanks for the summary It was a good read and you nailed it!
The final issue that led to the scrub was that a pin that held back the QD arm got bound and would not release.
First item is wrong - scrub was due to hydraulic pin on launch QD arm not releasing (apparently when released it caused an arm vibration that triggered a re-lock) and they had to improve arm stabilization when pin releases.
Also Ship reached original intended orbit.
A tower catch was never in the plans for this flight.
“seems to have hit the water harder than expected and was very off target.”
SpaceX’s people were saying it was on target, and it seems to have landed in about the same position relative to the camera buoy as previous flights. I don’t think there’s any evidence to call it off target. The landing and toppling looked the same as previous flights too.
You've mixed up the ship and booster.
Yep, I did. Thanks.
Fantastic summary. Thank you!
They've made great progress but have a bit left. It's always the last mile, isn't it?
It's so cool seeing progress in this space (sorry).
It was also noticeably wayyy faster off the launch mount. These V3 raptors are pretty fierce. It took off so fast it seems destined to be stretched imminently.
V2 they were bring them up in groups. V3 they start them all up at once.
Did the landing burn light two engines as expected? It happened fast, but the graphic made it look like only one lit. If that’s true, that would be impressive as only lighting two was meant to be a test. At least according to the live stream hosts.
Thank you for your service! You nailed every single detail.
This was as good, if not better, than the livestream itself!
Booster is a totaly new rocket. It did launch with acarity and by any other standard did well, but the failure to relight could be anything, but I am going for the giant fuel feeder tube bieng the failed part, based on nothing more than how tickled they were with it,and tank baffling bieng a dark art. The slosh of the fuel durring the flip is going to produce an internal tidal wave, lots of stuff gets "tested" there.
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Lots of engine failures. Doesn't exactly bode well for a company looking to go public immediately. One of the engine failures was not on the booster but Starship as you noted, and that is a bit unexpected. I don't think they have spoken about it being equal in capability with one engine out, right? Those engines don't move around to compensate IIRC.
Not sure how you come to that conclusion. The capabilities can overcome loss of engines. The fact it was successful with loss of engines shows it is working as designed.
No, it just means the mission happened to be salvageable because of its parameters. The booster is designed to have engines out and can compensate because it has so many engines and many of them are on gimbals. On starship, the vacuum engines aren’t on a gimbal. I’m not sure how it could compensate for one of three engines being out.
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And the “side effect” of polluting the ocean? SpaceX is more of a let’s only do things half way kind of company it seems.
Polluting with what? It's mostly stainless steel and other inert materials.
You do realize that every company so far has been doing that to every booster for every launch, right?
There's 2 options if you don't want to drop stages back on earth. You don't launch, you land the stage.
SpaceX is the company that pioneered propulsive landing of a booster. You can say a lot about them but not that they pollute with dropping stages in the ocean. Even in absolute sense that doesn't happen often and that's ignoring that they put over 90% of all the weight in orbit nowadays
The takeoff looked almost normal but I noticed a slight drift from vertical, likely because one of the engines was dead or dying. Overall the V3 is supposed to be an upgrade but actual progress is more or less stalling compared V2.
I have a hard time saying that its stalled. For one we don't really have the hard data to quantify the V3s vs V2s actual performance. On their first flight we lost one on the booster and one on the ship. I don't know that the boostback burn problems are related to the engine themselves given that they had multiple failures and a premature cutoff. That feels like thats a problem upstream of the Raptor.
It is supposed to tilt away from the launch tower immediately, you can see this on previous flights. This keeps the engine plume away from the chopsticks and top of the launch tower.
Also an additional goal is to get the booster as far away from the pad as immediately possible in the event it falls back down.
The payload (100t) is at least double that of previous flights. It’s largest spacecraft ever flew. That’s some stalling
There is a slight tilt normally, but I agree it was more than usual.
Flight 12 flew a different flight path than previous test flights.
> The amazing views of the plasma during re-entry, something never seen live before starship, are now routine.
The word "live" is doing a lot of work here. Astronauts used to film the plasma going past the windows of Shuttle.
I remember as a kid my science textbook had a still of it to illustrate plasma.
> The word "live" is doing a lot of work here
A latency of a few seconds for streaming video compared to several months for a still photo from the Shuttle seems an entirely valid use of 'live'.
The difference here is a matter of AV technology improvements in the last 40 years.
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>> As far as overall progress from previous test flights goes, they're at least treading water while making many large changes.
What a kind take on what is again the continuous trend of: Every flight fails for a different reason. And they still cant make the most basic use case: https://www.instagram.com/p/DWzTFAEAhSe/