Starship – SN9 – High-Altitude Flight Test
youtube.comI've been so conditioned by how flawless SpaceX launches have tended to be over the last few years. It's exciting going back to not knowing what will happen during the stream. I'm reminded of the enthusiasm around the early Falcon 9 first-stage landing tests, when folks were attempting to reconstruct individual frames of footage from the first "ocean landings" just to get a small taste of what happened. I'm sure they'll nail this landing before too long.
The day before the NASA-crewed SpaceX rocket launch, Starship SN4 blew up on the pad in a massive explosion in south Texas.
I noticed the news barely covered it, and I thought at the time it might be to avoid casting doubt on the human-crewed launch.
https://www.dallasnews.com/business/technology/2020/05/29/wa...
COVID19 and the riots were the big stories. Without them, doubt the media would have been able to resist the drama of astronauts possibly blowing up by connecting the two different rocket projects.
It felt much less eerie as it had commentary this time (and probably because it wasn't the first Starship high-altitude flight), but on the face of it, it looked to be a rougher 'landing' than SN8. I'm sure they got a lot of data from it, but it looked like some of the debris was headed towards SN10 - definitely squeaky bum time then!
Can't wait to see this work, though, it really will be a step change for space exploration.
Yeah - it really looked like they just got lucky with the debris somehow avoiding SN10. I wonder what the reasoning was behind them even having SN10 on the other pad during this launch - surely it would have been safer to just keep it in a hangar until afterwards?
That opening shot with one spaceship launching while the other was still on the pad was priceless, though... and they are iterating so quickly that much of the value from SN10 was already gained in the manufacturing process.
As others mentioned, space in rocket build area looks like it's to a point where any delay in getting completed test articles to test stands, means delaying construction. I suspect they weren't completely confident when they'd get FAA approval after getting into a full launch cycle and being pretty clearly rebuked (pulling of the TFR and announcement of the scrub by the FAA). So better to get it to the stands so they could move on the fronts they could... but also to be understood...
There's probably a cost/benefit calculation here, too: SN15 has been said to be bringing significant design improvements over the current design they're flying, and SN10 is of the older design. SN11 is probably ready or very close to ready for "high-bay" stacking... SN10 was waiting in the high-bay along with the first booster (BN1)leaving really no room for anything else to go in there. SN12, also of the same older design is being pro-actively scrapped right now and SN13, SN14 are also not going to happen so they get to SN15 faster. They have a test article at the launch site (SN7.2) to test a different construction material (3mm think stainless steel vs. the current 4mm). All that said and done... I'm sure they want to get SN10 in the air and would be disappointed by losing it... but they already have their sights fixed on the future it doesn't completely represent.
Their hangars seem to be filling up and I am sure they want to make room for SH1 and SN11.
It was ready to go, they got a week's jump on setting it up, and it isn't as close to the landing site as it looks.
Win SN8 at least they had the engine firing itself through the nozzle. This time it seemed the others failed to start.
Suicide burns are probably a very bad idea when they have crews and passengers anyway. I assume they'll fire up the landing engines sooner and leave enough time for the vacuum engines to fire as backups if needed.
I think they will practice until they get the landing right all the time.
The engines with vacuum optimized nozzles are not suited for landing. They can not be gimbaled and are very over-expanded as well. I would not be surprised if the engines with vacuum nozzles destroyed themselves if they were fired at sea-level.
The engines were tested at sea level with the vacuum nozzle. Not being gimballed is bad, but they are throttleable, at least.
All these crazy failure modes will have to be tested before Starship is human rated.
You are correct. There is even footage from a test on Youtube. Thanks for pointing this out.
You don't want them running for long on full power, but it's probably OK to use them for slowing down an emergency landing if the sea-level engines become otherwise unavailable. The alternative, as we (and SN10) saw with SN8 and SN9 is not great.
Vacuum engines can’t be used at low altitudes, exhaust underexpansion cause flow to delaminate which will damage the nozzle which goes the way rocketry goes
They can't be used for long. The Raptor was test fired with the vacuum nozzle at sea level. Not perfect, but beats hitting the ground.
Looks like 1 of the engines failed to re-lit during the landing.
At least this time 1 of the engines was functioning correctly all the way to the explosion. This is an improvement over SN8 where all the engines failed to re-lit properly.
I've plotted a graph with these two data points and predict that it will successfully re-light all three engines in only two more tries.
The landing burn will relight 2 engines to slow down, then land on 1 engine.
SN8 was really close. Only a couple more seconds before the engine ate itself would do. :)
Uh oh, that means that in two more tries it will be relighting too many engines.
It is interesting and informative to compare SN9 to SN8.
SN8: https://youtu.be/ap-BkkrRg-o?t=6884
SN9: https://youtu.be/_zZ7fIkpBgs?t=704
With SN8, you can clearly see two engines lighting and burning properly until just before it (crash) lands.
With SN9, you can clearly see one engine lighting and burning properly, but the second engine did not light cleanly and did not stay lit.
I don’t think that’s quite right. With SN8 they ended up with low pressure in the header tank and not enough fuel for the turbo pumps.
A so called “engine-rich” burn resulted, which is why there’s a flash of green flame.
Total thrust was much lower than spec, hence the hard landing even though both engines ignited.
I'm surprised they aren't trying to light all three and then shutting down whatever doesn't light as needed for the landing burn.
Both of the failed landing have looked like propellant flow problems rather than true engine problems but even so I'd love the chance to get it "right" by getting it "wrong" in that the wrong engines fired up but it didn't hit the ground too hard.
From wikipedia:
> Three Raptor engines, including SN49. SN9 has had one cryogenic proof test and six static fires. SpaceX attempted to fly SN9 on 28 and 29 of January 2021, but failed to receive permission from the FAA. During landing, one of the engines failed to ignite successfully, causing another hard landing that destroyed SN9.
https://en.wikipedia.org/wiki/SpaceX_Starship?oldformat=true...
This test was slightly shorter than the previous one (6 minutes, 26 seconds vs 6 minutes, 42 seconds) Next launch is expected within February.
I was impressed that they confidently landed it right next to another prototype. I am sure they will stick the landing next time.
It is irresponsible and it seems to me that the only reason they risked millions of dollars in prototypes is for media attention.
Just because it looks cool is not a reason to do it.
> Just because it looks cool is not a reason to do it.
I'm pretty certain that 'looks cool' has nothing to do with it.
SN10 had to be moved away from the assembly point because SN11, SN12, etc are close behind. They needed the space.
Why wasn't SN10 further away? SpaceX is moving fast, and moving these building-sized craft around is slow.
SpaceX has a many years of experience in landing rockets. Perhaps more directly, they have a lot of experience in failing to land rockets. To that end, they've use a kind of 'fail safe' methodology, where for most of the approach, the vehicle's trajectory is toward a safe, low-value spot.
For example, during the booster return of the CRS-16 mission in 2018, there was a problem, so the booster automatically didn't translate back toward its nominal landing pad. https://www.youtube.com/watch?v=LFdep0qCmYA In that case, the problem ended up not being severe enough to cause a crash.
Since switching to low-cost stainless steel, SpaceX design philosophy is to rapidly prototype using low-cost materials and assembly line like mass manufacturing ("the machine that builds the machine").
They expect to lose many rockets along the way. They only put 3 raptor engines in there because that's the expensive part.
This is in contrast to the SLS where they spend 5 years and billions of dollars designing and building one rocket that's make of break, with the second rocket launching people.
The reason to do it is to speed things up. Spacex is willing to take risks for speed
We just have to work on that landing "A little bit".
Understatement of the day.
What's kind of odd is how the video has a weird 80s-90s era sci fi feel. All these years I've thought those special effects were terrible.
Seems they're still having problems with their headless tanks given it looked like the 2nd raptor landing fire flamed out immediately, even earlier than the previous flight. I thought they had switched to using COPVs but that either malfunctioned or didn't work as well as expected.
The last seconds looked almost CGI, it's awesome to be witnessing this. Wish I was close enough to feel that spaceship BOOM!
What I find odd is: when this thing is operational, passengers are supposed to ride through this "flip to land" maneuver?
If I've already signed up to ride a large soda can filled with 4,600 metric tons of cryogenic methane and oxygen into a near-perfect vacuum, only to re-enter the atmosphere at orbital velocity, I suppose I could deal with a flip maneuver.
I think the suicide burn will be dropped for passenger flights, but the flip is an integral part of the braking maneuver.
Starship won't suicide burn. Raptor can downthrottle deeply enough to hover.
What would they replace it with?
Seems like there are two different things here; launching passengers and freight, and returning passengers in comfort and without neck injuries. One could easily envision a passenger only winged glider similar to the space shuttle to serve the passenger return role. Indeed, although spacex has nothing like that planned, these BFRs enable damn near anything.
Maybe some gyroscopic passenger seats that stay in one position relative to the ground so that they only feel g's going in one direction instead of being rag dolls.
The atmosphere on Mars is not as thick as ours so there might be an issue with that winged glider vision. And then there is the moon...
Both have much weaker gravity though.
But that doesn’t help when you have zero atmosphere. Zero times anything is still zero. And doesn’t help enough when the atmosphere is too thin.
I'd advocate for doing the flip on three engines for the added redundancy, then hovering for a second or so before landing; at least for passenger flights.
I think the idea is that two is redundant for the final design, but these test articles don't have the high power maneuvering thrusters. Without those they need to use the backup engine to manage the rotation.
The flip will be less extreme in later designs because they will have better/larger RCS control thrusters to rotate it without involving the main engines.
Also the center of rotation can be controlled to be inside the passenger section. Add some seats that can automatically tilt 90 degrees and the forces might be barely noticable.
Well apparently they’re looking into ways to catch the rocket with a landing arm looking platform. Really I think they need to get those engines to fire in any circumstance. But with N=2 it’s hard to know anything.
That's for the booster. The goal is to skip landing legs for the booster, as it'll only operate around Earth, so it's "easy" to build infrastructure instead.
Starship (the 2nd stage) will always do that flip & land on legs, as it also needs to do it on Mars.
The catching arm is for the first stage, IIRC
Second stage has always been about that flip, be it on the Moon, Mars or Earth
No flipping on the Moon since it provides no advantage there (No aerobraking)
That's a very good point. Looks like my brain also had a major malfunction ;)
They sure are!
It looked like something from the engine fell off during the flip
If you look at ~6:37 or so at the video of the engines it looks like they have a low pressure fire/leak lapping at the outside of the engine. Presumably that is not a good idea since they are running sensors/electronics there?
Anyone guess whats going on?
And that's why you have an assembly line for Starships: https://i.redd.it/dmr9bjhpcee61.jpg (SN9 lacking the RUD symbol in that image of course.)
Amazing to witness this, although I must say I preferred the camera angles we had in the SN8 stream. Seeing SN8 flip from a distance was great but with SN9 we had to watch it from underneath.
A bit earlier in the stream they tried to show footage from the rocket but the feed kept cutting out. That's probably why they didn't end up showing video of the engines during the landing like last time.
Yeah :( Although even at the start when they had the feed they only switched between them instead of showing both.
IMO Everyday Astronaut has the best video of the landing (https://youtu.be/l4-PwxnJimg?t=16263) - this is similar to what SpaceX had with SN8
Well they’ll stick the landing one day but just not today :(
That's a whole new meaning to halt & catch fire.
The lithobraking maneuver was sub-optimal.
Controlled descent into terrain.
SN9 knew the ground was where it was, but had an engine mishap preventing power to match control, so I’m debating with myself whether it was CFIT or UFIT. Maybe a superposition of both?
I think it was absolutely sure it was in CFIT and then it realized, suddenly, it was actually in UFIT.
It was a little more boring than the engine-rich exhaust of SN8.
In this case, it's more like halt OR catch fire.
Another hidden advancement by SpaceX/Elon, rocket launching now is way more normal as a business activity. It used to be rocket launch failure is world news worthy; now people feel relaxed watching a giant rocket crash into ground and turned into a splendid fireball.
This change in perception from the public, is the most critical change to fundamentally accelerate the progress of space exploration.
Looked to me like they didn't rotate all the way back to vertical, either.
I think it was the opposite; they rotated past vertical. I'd guess they were probably counting on the vectored thrust of a second engine to halt the angular momentum.
Sure, could be. I'd like a few seconds earlier on the shot that showed the landing pad to be sure.
dodd's stream shows that more clearly https://twitter.com/Erdayastronaut/status/135674067395381658...
boom
oh no!