Author Topic: Abort options for Starship and Starship/SuperHeavy  (Read 273325 times)

Offline Lee Jay

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #240 on: 11/29/2022 12:00 am »
You're arguing that it'll take less time to design, build, test, and qualify a crew system on a completely new propulsive stack, with a completely new entry/descent regime, with a completely new (and terrifying) landing mechanism, than it would to build in an escape mechanism to take most of the risk out of said new propulsive stack and terrifying EDL system.  That doesn't make any sense.

I am arguing that, and it does make sense ;)

You're argument is based on the idea they are going to have 2000 successful launches and landings in 6 years.

I think that's well beyond optimistic and infringing on delusional territory.

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The new regimes will be tested 400 times by about 2027 or 2028.  The cost for 400 times is $4B or less than Dragon2, and that doesn't include "we are already doing this for a profit".

I could have sworn you said 2000 above.

BO had one in flight abort test and one successful activation.  It's a simpler problem than doing EDL on Starship using an approach that has never been tried.

Offline Robotbeat

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #241 on: 11/29/2022 02:54 am »
I don't think 400 flights is *that* unreasonable, seeing as they're doing about 100 flights per year with Falcon 9.

Blue Origin took an extremely long time to get there with New Shepard, and it only does like 6 people at a time and flies so rarely that there's no way to get the launch history to prove it's any safer. I can see SpaceX pursuing beefed up ejection seats or something, but a full abort capsule is just not happening, sorry Lee Jay.
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Offline Lee Jay

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #242 on: 11/29/2022 03:48 am »
I don't think 400 flights is *that* unreasonable, seeing as they're doing about 100 flights per year with Falcon 9.

Blue Origin took an extremely long time to get there with New Shepard, and it only does like 6 people at a time and flies so rarely that there's no way to get the launch history to prove it's any safer. I can see SpaceX pursuing beefed up ejection seats or something, but a full abort capsule is just not happening, sorry Lee Jay.

I know, but it's an intrinsically unsafe system.

This is what I remembered:

"2 thousand EDLs at ops of 1 launch per day is 6 years.  I bet an abort system would take at least 7 years to qualify.

2 thousand launches at $5M/launch is $10B.  Much of which is profitable Starlink or 3rd party launches."

Offline sebk

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #243 on: 11/29/2022 09:08 am »
You folks have cornered yourselves into an either-or argument.

Developing large (2.5x liner dimesions of Dragon) separable capsule with pressure fed or solid motors, guidance, stabilization, landing system (either parachutes beyond anything ever developed or powered landing system) etc. is a big project taking multiple years and multiple billions

Executing 400 or 2000 EDLs is a big project taking multiple years and multiple billions.

From quite a bit of time in this thread I'm arguing for using "plain" "mundane" zero-zero ejection seats. Should be good enough for about 12 person crew. And 12 person is what's needed or more what's needed for Artemis, Dear Moon, Polaris 3, Tito's Moon flight, LEO space station ops, inaugural Mars missions, Venus flyby, or whatever.

Zero-zero seats is a known tech, with existing components, supply chains, etc. Of course they would need heavy adjustment and a lot of development. But scale of the development would be much less, the capital expenses to do tests on test tracks, towed sleds, etc would be much less than a capsule, because appropriate scale test facilities already exist, and ejection seat assembly is much less work and cash compared to 12 person capsule. Moreover whole components like parachutes, floatation devices, motors, are essentially OTS.



Offline DanClemmensen

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #244 on: 11/29/2022 01:09 pm »
You folks have cornered yourselves into an either-or argument.

Developing large (2.5x liner dimesions of Dragon) separable capsule with pressure fed or solid motors, guidance, stabilization, landing system (either parachutes beyond anything ever developed or powered landing system) etc. is a big project taking multiple years and multiple billions

Executing 400 or 2000 EDLs is a big project taking multiple years and multiple billions.

From quite a bit of time in this thread I'm arguing for using "plain" "mundane" zero-zero ejection seats. Should be good enough for about 12 person crew. And 12 person is what's needed or more what's needed for Artemis, Dear Moon, Polaris 3, Tito's Moon flight, LEO space station ops, inaugural Mars missions, Venus flyby, or whatever.

Zero-zero seats is a known tech, with existing components, supply chains, etc. Of course they would need heavy adjustment and a lot of development. But scale of the development would be much less, the capital expenses to do tests on test tracks, towed sleds, etc would be much less than a capsule, because appropriate scale test facilities already exist, and ejection seat assembly is much less work and cash compared to 12 person capsule. Moreover whole components like parachutes, floatation devices, motors, are essentially OTS.
Furthermore, ejection seats were actually implemented and flown on the first Shuttle missions, so this is not some sort of theoretical design exercise. Yes, they take up a lot of mass and volume, but if it's the quickest way to get a 12-person crewed Starship certified, then it's probably worth it. The cost savings of retiring Crew Dragon a year early (i.e., about 3 flights) would likely pay for the development.

Offline JimTheBeet

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #245 on: 11/29/2022 01:16 pm »
If I remember correctly, ejection seats on a rocket have a pretty sketchy history. There's a reason they removed the seats from Shuttle, and there's a great (Scott Manley?) video on how the seats on Gemini were a recipe for RULR (rapid unscheduled leg removal). Ejecting at such an odd angle isn't easy! I don't exactly have a better solution in mind though  ;)
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Offline DanClemmensen

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #246 on: 11/29/2022 01:28 pm »
If I remember correctly, ejection seats on a rocket have a pretty sketchy history. There's a reason they removed the seats from Shuttle, and there's a great (Scott Manley?) video on how the seats on Gemini were a recipe for RULR (rapid unscheduled leg removal). Ejecting at such an odd angle isn't easy! I don't exactly have a better solution in mind though  ;)
Abort is fairly high risk no matter what, but apparently one of the biggest uncertainties during Shuttle was that abort while the SRBs were still firing was problematical, and of course this included the critical first moments of the flight.  This is not an issue for Starship (which has other issues).

Offline sevenperforce

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #247 on: 11/29/2022 02:38 pm »
If I remember correctly, ejection seats on a rocket have a pretty sketchy history. There's a reason they removed the seats from Shuttle, and there's a great (Scott Manley?) video on how the seats on Gemini were a recipe for RULR (rapid unscheduled leg removal). Ejecting at such an odd angle isn't easy! I don't exactly have a better solution in mind though  ;)
Yes, there is a reason why they removed the ejection seats from Columbia, the only Shuttle to have them: the pilots requested that they be removed. Only the first two seats had the capability for ejection. The other seats, behind and below, did not. The pilots never wanted to be in a position where they could eject and try to save themselves by dooming their fellow crew members.

There was also a general consensus that the exhaust plumes of the solid boosters would have torched anyone who actually did eject. Not a problem for an all-liquid propellant system.

Offline Barley

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #248 on: 11/29/2022 04:01 pm »
People are getting hung up because they have a fixed schedule in mind.

The rational way to do this is to launch and recover SS enough that it becomes reliable.  How many flights that takes and how long does not matter as much as that it gets done.  You have to do this if you intend to use SS for Starlink deployment, so you get a large part of your reliability "for free".

Any abort system is an additional cost, which may be avoidable.  Not only will the abort system have a development cost, but it will have a high ongoing cost.  You should certainly try to avoid that. 

Adding an abort system is the type of heroics that has no place in engineering and has crippled human spaceflight for the last 40 years.

NASA may have a timeline in mind that requires certifying SS for human launches before getting much experience.  If NASA requires a launch escape system they should pay for it.

Musk may have a timeline that requires human launches before SS launches a lot.  He does not report to NASA.  There are presumably some constraints somewhere on risk, but cave diving is legal.


Offline Lee Jay

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #249 on: 11/29/2022 04:11 pm »
People are getting hung up because they have a fixed schedule in mind.

The rational way to do this is to launch and recover SS enough that it becomes reliable.  How many flights that takes and how long does not matter as much as that it gets done.  You have to do this if you intend to use SS for Starlink deployment, so you get a large part of your reliability "for free".

What if it takes a couple thousand successful landings without a failure (as it does for airliners), and you *never* get a run that long without a failure during LEO launch operations?

Offline Robotbeat

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #250 on: 11/29/2022 04:14 pm »
People are getting hung up because they have a fixed schedule in mind.

The rational way to do this is to launch and recover SS enough that it becomes reliable.  How many flights that takes and how long does not matter as much as that it gets done.  You have to do this if you intend to use SS for Starlink deployment, so you get a large part of your reliability "for free".

What if it takes a couple thousand successful landings without a failure (as it does for airliners), and you *never* get a run that long without a failure during LEO launch operations?
”What would you do if the Earth gets hit by a comet the size of Texas?”
“Well, I guess I’d just die?”

Sometimes, you just fail. The vision Starship was created for requires the launch vehicle to be that reliable in order to meet its goals of costs anyway. They might never get there, but Falcon 9 is approximately within an order of magnitude of that already (in terms of consecutive successful launches and consecutive successful landings), so it is a reasonable goal.

Asking what would they do if they fail to achieve that goal… well, then they failed to achieve the goal. Not a hard question to answer. Tautological.

I think 2000 is unnecessary, though. 400 is enough to prove more reliable than any crewed launch system, with or without LAS, has ever proven itself. From that point they’ll be able to prove out thousands of flights.
« Last Edit: 11/29/2022 04:20 pm by Robotbeat »
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Offline InterestedEngineer

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #251 on: 11/29/2022 04:21 pm »
From quite a bit of time in this thread I'm arguing for using "plain" "mundane" zero-zero ejection seats. Should be good enough for about 12 person crew. And 12 person is what's needed or more what's needed for Artemis, Dear Moon, Polaris 3, Tito's Moon flight, LEO space station ops, inaugural Mars missions, Venus flyby, or whatever.

Last one off the ship is a rotten egg!

Or rather, a crispy critter, as between 1-12 exhaust plumes impinge on their ejecting pod.

Ejection seats don't scale.

Offline Lee Jay

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #252 on: 11/29/2022 04:23 pm »
People are getting hung up because they have a fixed schedule in mind.

The rational way to do this is to launch and recover SS enough that it becomes reliable.  How many flights that takes and how long does not matter as much as that it gets done.  You have to do this if you intend to use SS for Starlink deployment, so you get a large part of your reliability "for free".

What if it takes a couple thousand successful landings without a failure (as it does for airliners), and you *never* get a run that long without a failure during LEO launch operations?
”What would you do if the Earth gets hit by a comet the size of Texas?”
“Well, I guess I’d just die?”

Sometimes, you just fail. The vision Starship was created for requires the launch vehicle to be that reliable in order to meet its goals of costs anyway. They might never get there, but Falcon 9 is approximately within an order of magnitude of that already (in terms of consecutive successful launches and consecutive successful landings), so it is a reasonable goal.


I think the longest string of successful landing is in the high 70s.  That's 25 times fewer than airliner certification, and over 10,000 times fewer than airliners in service.

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Asking what would they do if they fail to achieve that goal… well, then they failed to achieve the goal. Not a hard question to answer.

Which means it's never capable of launching the public, only those willing to accept a far higher chance of dying that the general public accepts.

That's conceptually fine, but killing people once in a while also puts a big stain on the whole HSF industry, so it's not just a matter of, "well, they signed a waiver knowing what they were getting into."  And that can cause years or decades of delays to the whole concept of human exploration.

Offline InterestedEngineer

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #253 on: 11/29/2022 04:24 pm »
I could have sworn you said 2000 above.

When your debate opponent freely concedes 2000 down to 400, you don't look the gift horse in the mouth ;)


I think the number is between 200-2000.   2,000 if a lot of failures happen at between flights #100-#500.   200 if everything goes swimmingly with no failures after about flight #20.  Not likely, but possible.

Offline InterestedEngineer

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #254 on: 11/29/2022 04:36 pm »
That's conceptually fine, but killing people once in a while also puts a big stain on the whole HSF industry, so it's not just a matter of, "well, they signed a waiver knowing what they were getting into."  And that can cause years or decades of delays to the whole concept of human exploration.

Elon needs to worry about fear of death as much as he does about wokeness if he wants to get to Mars.

The inability to accept all our common fate (death), can and will hold civilization back from big projects like colonizing Mars.

A bit of a side note, but back when all combat was low tech melee, battles were a game of chicken.  The first side to run away got run over and slaughtered by the enemy's cavalry.

Which mean the side that was most afraid of death tended to be the ones that died sooner, in greater numbers, and more horribly.   Quite the quandary.

Getting back to our topic, if there's a launch window to Mars, and 12 ships are lined up, and the 3rd one has a failure (abort or not), do we send the other 8 on?  Window is tight.   Failure to send the other ones means human and material resources will be compromised on Mars, leading to even more potential death on Mars, which will be resource starved for quite a long time.

An abort system doesn't change that calculus much.   The current standard is to "Shut it down and investigate the accident", and it doesn't matter whether there was a successful abort or not for that standard.

That process is fundamentally incompatible with interplanetary launch windows.

If you can make an exception to "stop all launches" if an abort system is present *and works more reliably than the rocket that has done iaunch/EDL 400 times*, that might provide an incentive to actually build an abort system.

Offline spacenut

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #255 on: 11/29/2022 04:58 pm »
Which is the most dangerous?  During launch or during landings.  Once Starship gets operational with launching Starlink satellites, NASA's lunar Starship and orbital refuelings, I think the launches would not be a huge problem.  I think the landings are going to be the most dangerous. 

Then, what about small self contained ejection pods that have parachutes.  This could protect on launch and landings.  Have them slightly angled outward and upward.  It does limit the number of crew and takes away from payload mass. 

Then, you can always launch a crew Starship, then send up crew with Dragon Capsules.  This kind of defeats the purpose of Starship being used to land on Mars, take off from Mars, and land back on earth.  Landing back on earth could be eliminated by putting the return Starship into earth orbit, and using Dragon Capsules for landing return crews.  You still have to land and launch from Mars. 

I think with the 100's of Starlink launches, problems with the Starship will be 99% eliminated.  At 100 Starlink per Starship launch, that is 420 launches needed to complete the Starlink constellation.  Even if the Starlink 2 or Starlink 3 satellites are heavier and they can only launch 50 at a time, that is 840 launches.  10 times per Starship is 84 Starships needed with say 20-30 boosters.  They have one launch pad, have another at 39A at the cape.  Possibly building a 3rd one at the cape.  They could do 8 launches a week for 2 years and finish Starlink installation.  That would not be hard to do with 2-3 pads.  Surely this will prove out the system and they may not need any other abort options.   

Offline InterestedEngineer

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #256 on: 11/29/2022 05:22 pm »
Which is the most dangerous?  During launch or during landings.  Once Starship gets operational with launching Starlink satellites, NASA's lunar Starship and orbital refuelings, I think the launches would not be a huge problem.  I think the landings are going to be the most dangerous. 

Then, what about small self contained ejection pods that have parachutes.  This could protect on launch and landings.  Have them slightly angled outward and upward.  It does limit the number of crew and takes away from payload mass. 

Then, you can always launch a crew Starship, then send up crew with Dragon Capsules.  This kind of defeats the purpose of Starship being used to land on Mars, take off from Mars, and land back on earth.  Landing back on earth could be eliminated by putting the return Starship into earth orbit, and using Dragon Capsules for landing return crews.  You still have to land and launch from Mars. 

I think with the 100's of Starlink launches, problems with the Starship will be 99% eliminated.  At 100 Starlink per Starship launch, that is 420 launches needed to complete the Starlink constellation.  Even if the Starlink 2 or Starlink 3 satellites are heavier and they can only launch 50 at a time, that is 840 launches.  10 times per Starship is 84 Starships needed with say 20-30 boosters.  They have one launch pad, have another at 39A at the cape.  Possibly building a 3rd one at the cape.  They could do 8 launches a week for 2 years and finish Starlink installation.  That would not be hard to do with 2-3 pads.  Surely this will prove out the system and they may not need any other abort options.

I agree.  The launches should become more reliable than F9's record number of consecutive successful launches fairly quickly, eliminating the need for a launch abort.

The landing is still risky.   There are still too many single points of failure

What does a landing-only "abort" option look like? (really a backup plan)

I doubt they can flip at a high enough altitude to deploy chutes fast enough to drop the terminal velocity to 20m/sec instead of the 70m/sec that Starship already has.   The chutes, according to a standard chute calculation, have to be 4,900 square meters.  Yikes.

https://wiki.freecadweb.org/Rocket_Parachute_Size_Calculator


Offline TheRadicalModerate

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #257 on: 11/29/2022 08:57 pm »
What does a landing-only "abort" option look like? (really a backup plan)

I doubt they can flip at a high enough altitude to deploy chutes fast enough to drop the terminal velocity to 20m/sec instead of the 70m/sec that Starship already has.   The chutes, according to a standard chute calculation, have to be 4,900 square meters.  Yikes.

You're never going to land a whole Starship on a parachute.  That's why you need an escape capsule.  The capsule weighs maybe 20t, which is a lot for a parachute, but the capsule also has propulsion, which can either land the capsule on its own or reduce the chute opening speed enough to make chutes manageable.

Given that, here are the major abort cases:

1) Pre-launch pad abort:  Capsule launches propulsively, more or less straight up, then lands nearby.

2) Low-altitude abort (i.e., too low and slow to count on the Starship being able to stage and do its own abort): Capsule separates propulsively, then lands nearby.

3) Mid-altitude, pre-max-q abort:  Starship separates, maneuvers into belly-flop mode, and lands on the chopsticks.

4) Max-q abort:  Capsule separates propulsively (high thrust needed), then lands downrange.

5) Hypersonic ascent abort:  Separate the Starship.  If it can do an RTLS, it lands on the chopsticks.  If it can't, it scrubs speed, goes into belly flop, does the flip fairly high up, and the capsule propulsively separates at the proper altitude.

6) Abort to orbit, abort once-around, or emergency abort from orbit:  This is a toughie:  Do you just rely on the Starship, which by definition has had some emergency, or do you engineer an escape capsule that can do a full EDL?  It's a big heat shield, with lots of stability problems, and it likely rules out the ability for the capsule to land propulsively, requiring a very heavy and complicated parachute landing.  My guess is that abort to orbit with a rescue will be the best choice.

7) Hypersonic descent abort:  This one can't be handled.  Loss of crew.

8) Off-target landing:  Do a regular hypersonic entry and belly flop, flip high, and separate the capsule, which lands on a rough surface or in the water.  Either way, the capsule landing is a lot more likely to be survivable than landing the whole Starship.

9) Flip problem: Capsule may have to propulsively separate in some direction other than up.  However, if crewed Starships flip high up, there's plenty of altitude to get stable.  Steer to vertical, then do the normal capsule landing sequence.

10) Post-flip landing emergency:  Capsule separates propulsively, then does the normal landing sequence.  Note that this will work even in the chopsticks or on the ground, if necessary.

I suspect that SuperDracos would work fine for propulsive aborts.  Since crewed flights will be comparatively rare and the idea here is to have an LEO ferry variant only, servicing hypergols and pyrotechnics isn't a huge cost.

The capsule is indeed a lot of work.  Getting a fairing that can carry reentry loads and the canards for a nominal landing but still blow away to enable capsule propulsion is also a challenge.

Offline InterestedEngineer

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #258 on: 11/29/2022 09:20 pm »
Getting a fairing that can carry reentry loads and the canards for a nominal landing but still blow away to enable capsule propulsion is also a challenge.

Yeah, I'd like to see how separating header tank piping is going to work.

Offline eriblo

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Re: Abort options for Starship and Starship/SuperHeavy
« Reply #259 on: 11/29/2022 09:45 pm »
[...]
The capsule is indeed a lot of work.  Getting a fairing that can carry reentry loads and the canards for a nominal landing but still blow away to enable capsule propulsion is also a challenge.
Looking at that list and comparing to the requirements for the current Starship program suggest that the abort capsule development program will be larger/longer/more expensive...

Tags: LAS black zones 
 

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