Quote from: TheRadicalModerate on 11/28/2022 09:33 pmYou'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 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.
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 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.
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 billionsExecuting 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.
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
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".
Quote from: Barley on 11/29/2022 04:01 pmPeople 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?
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.
Quote from: Lee Jay on 11/29/2022 04:11 pmQuote from: Barley on 11/29/2022 04:01 pmPeople 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.
I could have sworn you said 2000 above.
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.
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.
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.
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.
[...]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.