SpaceX SN9 Explodes on Landing
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"I bet they needed that."
As others have noted, SN10 is standing by. Somewhat uncomfortably close by: https://i.imgur.com/F9rsBbD.png
It's so exciting to be a spectator of these events.
The debris does not seem to come from next to the failing rocket engine but from the outer wall next to the engine that was not used in the landing attempt. It appears first shortly before the clock shows 6:21.
That was my immediate comment at the end. Pretty confident they are.
Or alternatively during fuelling, SpaceX had that issue during Amos-6.
This is 4k slow motion and it is gorgeous. The giant sheets of stainless steel floating down at the end are noteworthy, among other details.
Michael Bay has nothing on Cosmic Perspective + SpaceX.
1. Is it light enough to fly?
2. Is it strong enough to not cause a failure?
#shipit
One Starship requires 15 rings, a nosecone, a bottom and tanks. If they would all move from 4mm to 3mm then that would save a lot of weight. About 7-10 tonnes according to [1].
[1]: https://forum.nasaspaceflight.com/index.php?topic=52701.160
1.) Experiencing history in the making, especially knowing that the SpaceX team will eventually get it right. 2.) Realizing that even the best of the best have repeated failures and need to rely on iteration to get "there."
This seems to have caused at least part of their recent issues with the FAA, who seem to be less ok with explosions. It will be very interesting to see if this iterative approach leads to more reliable rockets down the line!
That's not quite the same situation SpaceX is in right now.
Anyway, landing Starship involves a bunch of things never before attempted: landing a fully-reusable second stage, landing a vehicle of this size, relighting and running engines during the belly-flop-and-flip maneuver, and flying and relighting full-flow staged-combustion engines. Probably some other firsts too.
Thrust given to show difference in engine scale. Pressure isn't shown - what do you mean? :)
The point is that re-light of Briz and Fregat is very different and so hard to compare.
In fact, in over 100 flights, SpaceX did not have a single failure of a Second Stage engine not starting or not re-lighting. This is unlike Arianespace who just had a failure when they tried to start an engine on one of their upper stages.
Outside of that Merlin is easily the engine that can be re-lit more then any other on the planet and its not close.
This however is a non-commercial prototype, where they are testing new technologies. Its a completely new engine of a type that has never flown before and is not finished developing. The vehicle has been newly designed and it does things no other vehicle has done before in a way no other vehicle has done before.
You honestly just sound like an incredibly petty hater. I can grantee you that Russia and Europe have plenty of issues with engine starting on their development engine.
It's very difficult because of the turbulent airflow in an engine bell pointed against the airspeed vector. Despite this, many rocket engines can do it reliably.
That's not a failure, that's the effect of some upstream failure.
What failure are they repeating? Pumps sized too small? Improper torquing? You talk like you know the details, so share them.
How exactly you decide to fix it depends on many things. It's impossible to tell. But they are all downstream of the same failure, which is overcoming the high pressure and turbulent flow.
>At an altitude of about 1.5 kilometers (5,000 feet), the lander activated its three retro-engines and was released from the parachute. The lander then immediately used retrorockets to slow and control its descent, with a soft landing on the surface of Mars.
Unless you go back to the early pre-Mercury program days of NASA - they had lots of failures, and that was just trying to go up without re-usability, not land and reuse. There's all kinds of fun failure reels (e.g., [1]) and lists (e.g., [2])
[1] https://www.youtube.com/watch?v=g79K-R7xTFo [2] https://en.wikipedia.org/wiki/List_of_spaceflight-related_ac...
But alas, the aerospace world overlearned the lesson and has been cargo-culting it ever since. Mueller’s decision was purely a matter of expediency to meet Kennedy’s goal and beat the Russians. It wasn’t a statement that this was the best way to do engineering, absent those constraints. To make matters worse, all-up only works under the funding conditions of Apollo: a massive spike in funding to cover the up-front cost. Without that spike, the costly development phase has to be stretched out, and the whole thing ends up taking longer than iteration. In other words, you can save time this way when money is absolutely no object, but otherwise you lose time. See Boeing’s SLS: basically 15 years of development and they just static-fired it for the first time. Launch is maybe a year away.
We’ve all gotten used to the all-up style of development, and SpaceX’s rediscovery of rapid iteration makes it seem like a new and untested way of doing things. But I think the dominant narrative—that all-up is prudent and conservative while iterative is risky—is completely backward. All-up carries a massive amount of risk that fundamental design issues won’t become apparent until the tremendously costly development phase is done. Iteration allows assumptions to be tested and modified as quickly as possible. Most of SpaceX’s early ideas about reusability turned out to be wrong. If they had committed all the money and time to those early concepts before flight-testing, they would have never accomplished it. The early rocketry pioneers operated this way, and it’s why they accomplished the things they did. Maybe SpaceX will finally free the space industry from perpetually repeating what worked for Apollo, which after all operated under unique political conditions.
And combustion instabilities they were fighting were rather novel at the time, the engineers basically had no other options than to test a lot of variants - and invent debugging techniques with "bombs in the chamber" along the way. Fortunately it worked - low pressure of F-1 helped to mitigate problems of size.
Also, Combustion instabilities date back to at least the A4/V2, not quite new, and largely the same engineers.
1. turbo-pumps
2. the nozzle is cooled and the fuel warmed by making the nozzle out of tubes through which the fuel passed
3. holes drilled in the tubes so fuel leaked into the combustion chamber to provide boundary layer cooling
I think the pogo-ing was solved the same way, too - putting baffles in in various places.
Because NASA does not launch anything anymore. If they were doing hundreds of launches per year you can bet you'd see failures the whole time.
https://www.youtube.com/watch?v=bvim4rsNHkQ
It's easy to forget how many failures that had, but look how far it has come, at this point I don't think they've had any major failures in 5+ years. Maybe a couple sea drone ship booster landing issues but zero mission failures in a very long time.
Scott Manley and daughter have a fun song about other failures, "You will not go to space today", https://www.youtube.com/watch?v=Ayu0GsrvKQA
I'm guessing the title is probably an allusion to this https://xkcd.com/1133/.
"If an O-ring gets a bit too cold, you will not go to space today"
...but I guess that's a bit too dark, eh?
At least they didn't hit SN10!
Summary tomorrow in this week's Orbital Index (https://orbitalindex.com).
Or does it not matter because a few more seconds won't increase the chances they'll be able to relight?
But these are all in the 'why don't they' category, SpaceX has some pretty clever cookies, experts in their field, the chances that anything we can think of has not been thought of by them are nil.
Not saying that a bunch of random folks on HN are seeing dollar bills in this analogy, but I've never quite been satisfied with the "if we're thinking of it then they probably already tried it" explanation :)
Same here :) . I'm still unhappy with their decision to use toxic propellants on Crew Dragon - I'm sure they could use something much more benign.
They've had better fuel options from the very beginning. I guess they didn't have space cycles to additionally solve this issue; hope they'll come back to it.
"We were too dumb" https://twitter.com/elonmusk/status/1357256507847561217
If you want to start burning a few seconds early on landing by policy, you need to lift that fuel, and the fuel to lift that fuel, from the surface to space and then decelerate all of that. Just for those seconds. If you’re doing this from Mars, you also have to accelerate that mass around the Solar System and out of the Martian gravity well.
Not a bad thought. Just wanted to illustrate how energetically leveraged these systems are.
Starship is a more capable upper stage then Crew Capsule, part of which means that it can launch itself (at least suborbital). They aren't trying to qualify these prototypes as human-rated, they have to finish the design work first!
For this pase of testing it's much more accurate to compare to Falcon 9 than Crew Capsule.
All I am saying is that this vehicle, in it's final qualified form, will be landing human beings on the deck back here on Earth. That's the objective, so it's viability and reliability needs to be considered in that context.
For an F9 first stage a failure rate of 1/10 is fine. One out of 20 is outstanding. For Starship, these things are intended to carry a hundred paying passengers or more. The failure rate needs to be lower than 1 in a thousand. Much lower.
Launching these things IS the issue so far, by far the main objective of these tests. Landing them would be nice, but the primary objectives are to launch the whole thing (in particular including aero surfaces and multiple engines, as compared to previous prototypes) and test the various novel maneauvres that they are attempting. That almost all the objectives are being met in these tests is a testament to how good SpaceX is getting at launching flying water tanks, and how hard the entire flight profile is to achieve (launch, belly flop, landing flip, landing).
In the anticipated human-rated version of Starship safety will be immensely important, but this is nowhere near being that thing! This was only the second prototype that even started to look like 'Starship'. We have no idea what a human-rated version would loook like, and a human-rated Starship is definitely not the objective of these tests.
The Starship prototypes they are testing at the moment are much much much closer to a Falcon 9 than a capsule. Specifically the systems and processes they are testing all have fairly direct parallels in Falcon 9, and almost no correspondence to a capsule. For example, Falcon 9 and Starship both have: super chilled propellent tanks, multiple large rocket engines, active flight control systems, engine relight, active aero surfaces, and powered landing. Starship and the capsule both have... heatshields?
Human passenger safety will be immensely important for Starship, but to focus on it at this stage of development would be immensely premature.
They are doing these dramatic tests out in the open which sure gets a lot of attention, but there is a real risk of reputation damage or fodder in the hands of their competitors lobbyists.
I don't know a good way to resolve that, but I certainly prefer the current approach and trust that anyone who really cares about the safety will be able to understand what's important about these tests and what isn't.
Even on the crappy morning news here, where they certainly gave a lot of airtime to the fireball, they had an expert on who focused on what the test was aiming to achieve. There certainly was no focus on the idea that Starship is intended to eventually carry passengers (even though they mentioned it alongside stock renders of Starship going to mars and the moon).
Wow, I can't imagine a disaster happening in the United States where we barely even knew the order of magnitude of fatalities.
The two ways I heard to get really reliable products is to get good at manufacturing them reliably at scale or be really slow and really careful in making them one at a time.
Somehow that should be an Elon tweet.
The early starhopper/starship flights proved what they needed to that they'd generally land on target.
Their goals are to design a rocket system capable of landing on Earth, Moon, Mars and possibly others. Is must be able to refuel in space. It must be able to rapidly reusable, as in the same day multiple times. It must be cheap to manufacture, and it must be cheap to operate.
Every prototype brings in lots of new changes, none is exactly like that before, every around 5 prototypes there is a major generation upgrade. Every new prototype does not just test the new design, but also the improved manufacturing process.
All the learnings from both the build and the launch flow directly back to the developers and engineers working on it, and the required changes to into the backlog and eventually make it into later prototypes.
What the outcome of this process is, who knows unknown. SpaceX has shown to be incredibly flexible and change to new things quickly and without making a big deal about it. The change from carbon to stainless steel for example is a case where SpaceX had already tested tanks, they had already ordered tools, they had already bought a location. Within one month they dropped that. Iteration speed to slow, material cost to high, performance gain when combined with heat shield not worth it anyway.
Only when you consider cost, heat-shield consideration and iteration speed is it clear that stainless steel beats carbon fiber by a large margin.
The heat shield has been changed multiple times. The fins have been redesigned multiple times. The legs are a hot issue right now. The header tank design has changed over time. And so on and so on.
SpaceX will move forward like that, produce more and more prototypes that are closer and closer to the almost impossible goal. Every prototype is a fully integrated test from materials, design, manufacturing and operations.
SpaceX clearly took the Soviet's approach to rocket design.
EDIT: This is not a negative thing. Soyuz is pretty darn safe because of the approach they took.
The numbers don't really seem to support your assertion that NASA is generally much safer than Soviet/Russia
If you do more tests which kill more people before declaring the system good, you don’t get to not count those people like it’s a different color of money in some bureaucratic dystopia.
There was no panicky brain screaming "we need air" or any feeling of being O2 short. It was just normal breathing. If you're going to end it all that's the way to do it.
I wrote an incident report with the obvious suggestion to vent the reliefs outside. It was modified the next outage.
"The most recent estimated death toll, released by Roscosmos on the 50th anniversary of the accident and originating with agency engineer Boris Chertok, was that 126 people had died, but the agency qualified the number by saying that the actual number could be anywhere from 60 to 150 dead."
The Russian wikipedia article also has a list of 'other failures' - these are fires in an ICBM silo in Russia in 1960 - eight dead; the US had a fire in a Titan II bunker in 1965 that killed 53 and another one in 1980 that killed one man; also Brazil had a fire of a liquid fueled rocket that killed 21, also on start preparations. (and another blast in Plesetsk in 1973 that killed seven http://www.plesetzk.ru/index.php?p=1973&d=doc/disaster - wikipedia doesn't list everything)
Rocket fuel can be very dangerous stuff! At least liquid methane/oxygen aren't hypergolic.
https://en.wikipedia.org/wiki/1980_Plesetsk_launch_pad_disas... https://ru.wikipedia.org/wiki/%D0%9A%D0%B0%D1%82%D0%B0%D1%81...
[0] https://www.amazon.com/Ignition-Informal-Propellants-Univers...
So combining with your statistic the U.S. has a fatality rate of 4.4% versus Russia's 3.3%. Given the low N it's probably within margin of error.
Also, quite a few of those did multiple flights. Looking at that list, I think that moves the needle in favor of US rocket safety.
Soyuz has launched 394 people and killed 4 of them. The most recent fatality was 50 years ago. The Shuttle launched 833 people and killed 14 of them, most recently in 2003 (8 years before the program ended). That gives Soyuz a fatality rate of 1.0% and the Shuttle a fatality rate of 1.7%. In other words: You're 70% more likely to die if you ride the Shuttle instead of Soyuz.
The more you look into the specifics, the safer Soyuz seems. The Soyuz deaths were early in the program while the Shuttle deaths happened when the program was mature. (Soyuz 11 was the last fatality and it was the 10th manned mission. STS-51-L was the 25th Shuttle mission and was considered to be safe enough for a civilian teacher to ride along. Oops.)
Soyuz's design is inherently safer. It has a launch escape system (which saved the crew of Soyuz 7K-ST No.16L).[1] The Shuttle did not. Soyuz's heat shield is much more robust than the Shuttle's. Soyuz's crew section is on top of the rocket, reducing the chance that any falling debris (or shrapnel caused by an explosion) will harm the crew module. Lastly, Soyuz uses liquid fueled rockets that can be shut off at any time. The Shuttle's solid boosters could not be throttled or shut off. All of these design decisions make for a simpler and safer vehicle. If I had to pick one, I'd ride Soyuz for sure.
We can all see what happened: the soviets stopped spending money on innovation and tried to re-frame their stagnation as operational brilliance. Sure, Soyuz has a reliability niche, and I'd rather ride on it too, but I'd rather fund efforts to advance space exploration, even if they wind up being a clusterfuck like the shuttle.
On top of that, the Raptor engines used in the Starship, which seem to be considered state-of-the-art, are based on a soviet design from the 60s.
It's weird that people seem so keen to talk up the soviet part and talk down the US part.
But yet, if I say this, I will be immediately downvoted because if I suggest that anything other than the established order in the US is the best system, the powers that be as well as the indoctrinated individuals that frequent this place would rather just shut that conversation up than to engage it meaningfully.
What makes you think that? If they had such a wonderful "way to structure and run society in general", why did the USSR and its satellite states have to systematically mass murder people who wanted to leave this wonderful society?
[0] https://en.wikipedia.org/wiki/Emigration_from_the_Eastern_Bl...
[1] https://en.wikipedia.org/wiki/Schie%C3%9Fbefehl
[2] https://en.wikipedia.org/wiki/Mass_graves_from_Soviet_mass_e...
It's possible that the USSR would have been a better system, had the cold war not happened, but that's not the world we live in. If you want to make that argument you have to explain why it's reasonable to excuse how the USSR turned out in reality, and why in your hypothetical world it would have turned out differently.
With respect to space advancement, I suspect the main reason for sustained differences in accomplishments come down primarly to the amount of resources each were able to devote to space. The US was able to sustain a high level of investment for a long time, and the USSR was not.
https://capx.co/soviet-communism-was-dependent-on-western-te...
You go on to state that Russia beat the US into space (which is a non-sequitur), and later expand that "The USSR, had it not had to fight a cold war against the US, could very well have been a much better system not just for space flight, but for a way to structure and run society in general."
When challenged by alentist, who asked "why did the USSR and its satellite states have to systematically mass murder people who wanted to leave this wonderful society?" you countered with "If it was such a bad way of doing things, why did the US actively go out of it's way to sabotage it" which is moving the goalposts, and starts to slide into whattaboutism.
Specifically you claimed that the USSR "could very well have been" a better way to structure a society, and alentist provided strong evidence that it was not - people were murdered when they tried to leave. Instead of trying to prove your point you deflected, and shifted the goalposts from "this could very well have been a good system" to "the US didn't like it therefore it couldn't have been bad".
Still, it would have been better not to restrict emigration. That was not humane, and betrayed an antiquated view of how the world works.
Your question, on the other hand, is silly. Substitute the USSR with Nazi Germany.
If you're saying that slavery is also abhorrent and evil—like the slavery and mass murder that takes place under Communism—then we're in agreement. Now, can you please answer the question?
If the USSR had such a wonderful society, why did they have to systematically mass murder ordinary people who wanted to leave this wonderful society?
Let's try again:
If the USSR had such a wonderful society, why did they have to systematically mass murder ordinary people who wanted to leave this wonderful society?
Don't deflect. Don't evade. Answer.
To our fellow readers on HN: notice how alentist himself cannot answer a question asked back, even though I have given him the answer to his question directly multiple times. It is his attempt to save his narrowly constructed world view that he is right, America has never committed atrocities against its own people and others, and you should accept his point of view matter of factly without questioning! Notice how he acts more like the places he criticizes than I do simply for questioning his assertions?
When all major foreign powers say that they wish for the destruction of your country and would openly prefer you to go back to more suffering, support for monsters like Stalin increases.
Equally, when the threat of invasion is as high as it was for the USSR from Britain and the US, a lot of money and power is invested in the military.
It's very possible that if it wasn't for massive foreign interference neither Stalin nor Trotsky would ever have been able to gain much power (both of them got their power from military conflict mainly, Stalin even moreso), the NKVD never would have gotten nearly as much funding, Lavrentiy Beria would probably have been put against the wall, and so on.
The mere presence of the Bolsheviks as a dominant force was due to foreign interference, as the Germans installed him and his friends in an attempt to destabilize the Russian Empire.
Trotsky's growth in authoritarianism, when he was previously a moderating force, started with the opportunistic German attacks at the fleets of the Red Army, and of course his rise to power from a middling figure to a preeminent Bolshevik was only made possible by German incitement of the Bolshevik movement to begin with.
Even Stalin's justification for power was based on (justified) appeals to centrally planned heavy industries, whose main motivation was military power which was necessary to to threats of invasion.
It is clear to anyone that both Stalin and Trotsky would have had much, much less power if they weren't able to justify centralization on the necessity to resist foreign agression, beyond that the consolidation of the Bolsheviks to begin with was a German plot.
You cannot just sweep across decades of internal Russian conflict and paint it with such a broad and quite frankly misinformed brush. Every European nation was involved to some extent, but none had the influence you claim nor did any create any of the central characters in this story.
The phenomena of revolutions turning authoritarian because of an outside enemy attempting to destabilize is in no way unique to the USSR. It's a pattern you see all across the world. It's what gets a movement that was opposed to even the concept of a standing army because of the centralization of power and the risk that brings to the largest standing army.
The Germans didn't create Lenin, but they fundamentally changed the course of the Rebellion against the Tsar by sending him back to Russia at that precise time. They had an intent in doing so that was realized.
You: Exactly!
Glad you also agree with my comments, then.
>The USSR, had it not had to fight a cold war against the US, could very well have been a much better system not just for space flight, but for a way to structure and run society in general.
thus implying disagreements. Since neither of us have contradicted such a statement, either you've been replying hors-sujet or you were just trying to show agreement, right?
Your comment says otherwise.
https://www.amazon.com/Korolev-Masterminded-Soviet-Drive-Ame...
[0] https://space.stackexchange.com/questions/8330/what-is-the-c...
Of course, they'll have to land some other way on Mars or the Moon.
On earth it's also about spreading the heat of reentry over a larger area. Fortunately on Mars (I believe that) the heat of reentry is even less of an issue than here on Earth.
Are they planning on landing starships on earth? with Orbital refuelling couldn't they just land it like a Falcon 9 (I mean I guess that'd be super inefficient)
They plan to land passenger ballistic re-entry starships which fly without a booster directly to another city on earth in <30 minutes. These are going relatively slowly.
They plan to land orbital starships, which is like landing the dragon capsule. These are going far faster than the falcon booster ever goes. The second stage (on top of the falcon) never lands, it's disposed of every mission. The StarShip (top half) is essentially a reusable second stage.
The Starship mars or moon editions will remain in orbit and never land on Earth again after initial launch. These do not need hardware for an Earth descent and will rely on refuelling. The Moon edition will have no heat-shield tiles (no need for atmospheric entry) and special thrusters half-way up.
You are correct that interplanetry velocities are very high, so yes... a Mars entry at Earth-Mars transfer velocities is likely to be quite ... exciting. I can't remember how exciting though.
Starship is intended to re-enter from orbit, which is a lot faster. Using aero braking requires much less fuel, and avoids the need for a re-entry burn which may not even be feasible.
That phase wipes off >99% of the total energy required to get to 0 m/s, which is pretty remarkable because Mars' atmosphere is ~1% of Earth's.
That they (at least on paper) have a solution for this problem good enough for a 60 metrr craft weighting 100+ tons makes the whole thing even mord remarkable! :)
Good thing we have physics and math :)
Especially subsonic I assume their orientation does not matter a whole lot when just trying to fall with max drag.
Not sure how much energy they'll save doing the flip maneuver earlier though, seems like they want max drag as low as they can go, then flip to powered flight at the last moment possible -- and their problem seems to be keeping the engines lit.
(2) The Question: I ain't no rocket scientist, but even if the engine failure had turned on, did the engines all just turn on quite late?
Just trying here some crazy college physics so not sure if this checks out but, here goes. Again, just for fun. If it takes X: (summation of thrust) to fly that high over x seconds, then it would take the X + some at the very last 4 seconds I saw engines turn on for soft landing.
Are we capable of having enough thrust in the last 4 seconds? Maybe try earlier so there can be more lead way in case of failure?
===
Freefall: 11:06 (all estimates) 12:45 (still free fall, engines off and preparing for vertical) 12:48 (engine on, flipping for vertical) 12:50 (vertical) (4 seconds left to apply thrust) 12:54 (crash landing)
I have about 104 seconds of free fall, and 4 seconds left when engine turned on.
Is 4 seconds enough? Just intuition and genuinely wondering ...
Just for fun - does my physics checkout (at freefall)?
vf = 0 + (1/2) * at^2 vf = 9.8m/s^2 (108s^2) = 57153.6 m/s = 127848.9621 mi/hr (yea, ignoring at moment drag/terminal, physics ;)
===
vf = (1/2) (F/m)t^2, F=ma (vf2m) / t^2 = F (Thrust required)
Again, just for fun. Don't kill me. Physics, it been a long time. If it's right, Elon, are you hiring?
EDIT: SpaceX, Tesla to the -moon- mars!
The timing doesn't mean much because an entire engine didn't light... so it would have flipped up right faster and slowed down faster. Timing on a failure case doesn't really work.
Also it was only 1 engine compared with two, they could gimbal independently and have one course correcting while the other decelerates
1. The StarShip reaches a terminal velocity (in "the bellyflop") of about 200 km/h downwards and remains at that velocity until the "flip maneuver" at the end.
That's essentially a free force vector upwards due to drag which is free thrust on descent.
2. The weight of fuel reduces drastically on ascent which is why less engines are required as the StarShip soars higher into the air (they shut down when one reaches the 40% min thrust)
You'll see during the hover at the top that StarShip balanced on one engine for some time without moving. So that is the thrust required for station keeping. What we saw here was a combination of reaching a target location and burning excess fuel.
---
So, landing burn is (supposed to be) done with two fully throttled raptors, which is essentially 4x the hover thrust. Here with SN9 you see what happens when only one of those raptors is actually working.
Here is an Excellent SN8 (not SN9) video with carefully reconstructed telemetry (based on pixel counting video references) and you can see the velocities on descent. Rewind the video for full detail:
https://youtu.be/XJZ7VWzqtJM?t=867 [How to simulate a Starship launch!]
If they decide to lift the StarShip from sea level completely full they will need to use only sea level engines (not vacuum optimized) or risk engine damage. Of course in production the booster will put the StarShip (upper stage) well above sea level.
Caveat: Did I mistake the scope here? I’ve not checked to see at what point in the trajectory the engine actually failed as I am at work.
*deal with - meaning land successfully anyway
There is also a startup time for each engine, so if one fails Starship will likely hit the ground before they can light another.
There are enough engines that a failure on ascent can be handled gracefully but landing is another story.
With respect to failure on ascent, I imagine in that case they just send up another starship and transfer in orbit (coming down has always been the hard part).
But this is totally question to Raptor creators. Might be not really feasible or even meaningful.
It'll be interesting to see what exactly happened with SN9, there's some clear video footage of piece flying off the rocket right as it was doing the flip maneuver.
Define "deal with". This rocket did 100% of what any rocket was ever supposed to do, before SpaceX came along and redefined what a rocket is supposed to do: go up.
Manned space flight kind of has this kind of important additional requirement that things like ICBMs don't, which is that they can't just "go up" the have to come back down and not end in a ball of fire.
It feels to me like there is no backup plan for engine failures, but they can take so many paths here that I don't think anyone knows except people within SpaceX. Example paths:
* Don't launch it with people until it has landed unmanned so frequently that everyone trusts it. * Land cargo versions like this to get max payload, while manned versions light a lot sooner, with possibly more engines, and sacrifice some fuel for increased reliability. * Catch starship just like the booster in case of failure, with a longer travel to support higher speeds and lower G's. * Add a parachute or increase the flap sizes to lower terminal speed so much that it is survivable to land without engines.
The test articles for the first stage are still being built and are expected to land similar to the falcon 9, which the big difference that Elon is talking about them being catched by a tower instead of landing on their own legs. This seems far enough away though that I would not be surprised if that changes radically.
SN10, we're waiting!
The one where the front fell off?
What happens if the landing happens to occur during a 50 mph wind gust, etc. If this maneuver isn't designed to be 100% fault tolerant maybe they need to be thinking about an emergency eject?
I like the simplicity of the Starship design. How much extra weight would a nosecone eject + parachute add?
I prefer Dream Chaser's approach, but Elon Musk has his own ideas. Together with SpaceX team. Of course to fly to the Moon there are no such options.
It is a fair point though, that landing in less-than-ideal weather conditions should perhaps be thoroughly tested. Launches generally can be done when conditions are optimal, but it might not always be possible to defer a re-entry until weather improves.
Ideally the lander would have real-time high-resolution air velocity data in the vicinity of the landing pad and would adjust its maneuvers to compensate.
I wonder what SpaceX's current tolerances are for wind for Falcon 9 landings? I assume anything more than a light breeze and they put it off for another day, but maybe those rockets are heavy enough that the wind doesn't knock them around as much as one would expect. (Droneship landings are especially difficult with wind plus a rocking boat.)
For example shorter flight times mean fewer chances for in flight human errors. Another is in flight medical emergencies can be more quickly reach a hospital. A few aircraft have been shot down which is again much less likely, etc etc.
Initially it’s going to be risky, but give it say 50 years and it might actually end up being the safest option for ultra long distance travel.
The usual way that such engines are designed (for military or civilian aircraft) may be called the component system, or bottom-up design. First it is necessary to thoroughly understand the properties and limitations of the materials to be used (for turbine blades, for example), and tests are begun in experimental rigs to determine those. With this knowledge larger component parts (such as bearings) are designed and tested individually. As deficiencies and design errors are noted they are corrected and verified with further testing. Since one tests only parts at a time these tests and modifications are not overly expensive. Finally one works up to the final design of the entire engine, to the necessary specifications. There is a good chance, by this time that the engine will generally succeed, or that any failures are easily isolated and analyzed because the failure modes, limitations of materials, etc., are so well understood. There is a very good chance that the modifications to the engine to get around the final difficulties are not very hard to make, for most of the serious problems have already been discovered and dealt with in the earlier, less expensive, stages of the process.
The Space Shuttle Main Engine was handled in a different manner, top down, we might say. The engine was designed and put together all at once with relatively little detailed preliminary study of the material and components. Then when troubles are found in the bearings, turbine blades, coolant pipes, etc., it is more expensive and difficult to discover the causes and make changes. For example, cracks have been found in the turbine blades of the high pressure oxygen turbopump. Are they caused by flaws in the material, the effect of the oxygen atmosphere on the properties of the material, the thermal stresses of startup or shutdown, the vibration and stresses of steady running, or mainly at some resonance at certain speeds, etc.? How long can we run from crack initiation to crack failure, and how does this depend on power level? Using the completed engine as a test bed to resolve such questions is extremely expensive. One does not wish to lose an entire engine in order to find out where and how failure occurs. Yet, an accurate knowledge of this information is essential to acquire a confidence in the engine reliability in use. Without detailed understanding, confidence can not be attained.
A further disadvantage of the top-down method is that, if an understanding of a fault is obtained, a simple fix, such as a new shape for the turbine housing, may be impossible to implement without a redesign of the entire engine.
The Space Shuttle Main Engine is a very remarkable machine. It has a greater ratio of thrust to weight than any previous engine. It is built at the edge of, or outside of, previous engineering experience. Therefore, as expected, many different kinds of flaws and difficulties have turned up. Because, unfortunately, it was built in the top-down manner, they are difficult to find and fix. The design aim of a lifetime of 55 missions equivalent firings (27,000 seconds of operation, either in a mission of 500 seconds, or on a test stand) has not been obtained. The engine now requires very frequent maintenance and replacement of important parts, such as turbopumps, bearings, sheet metal housings, etc. The high-pressure fuel turbopump had to be replaced every three or four mission equivalents (although that may have been fixed, now) and the high pressure oxygen turbopump every five or six. This is at most ten percent of the original specification. But our main concern here is the determination of reliability.
The big bang (your words) or the top down (Feynmans words) method is what the SLS is doing. Not spacex.
SSME thrust-to-weight ratio: 73.1 https://en.wikipedia.org/wiki/Space_Shuttle_Main_Engine
NK-33 thrust-to-weight ratio: 137 https://en.wikipedia.org/wiki/NK-33 (no gimbaling)
RD-270 thrust-to-weight ratio: 189.91 https://en.wikipedia.org/wiki/RD-270
I wonder if recent departures are related in some way. They failed plenty before, but this seems different.
You can also see some debris fly off of the bottom of the rocket just as it's performing its flip maneuver.
With SN8 Musk tweeted casually about it, but he's apparently taking a hiatus for a bit.
Yes it is, but I didn't speculate as to how that might be related. It is a bit of a stretch.