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This question let me wonder whether SpaceX' Starship has a launch escape system. It really seems to have none. The obvious question is why not, it sounds pretty negligent to me not to have some kind of emergency security system. The Starship is so big, why can't it have launch escape thrusters like the Dragon spacecraft? I remind that the death of shuttle Challenger's crew could have been avoided if the shuttles had such emergency system, since the crew survived the initial explosion. If Starship isn't gonna have a launch escape system, I'd say they didn't learn their lesson from the Challenger disaster (but that's obvious anyway since the shuttles didn't get such system anymore until their retirement).

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    $\begingroup$ @geoffc It would be too much to have so many parachutes, for up to 500 people per airliner. But sailplanes do have parachutes. The shuttles and the Starship could (have) introduce(d) some too. If the Challenger crew had parachutes they might have saved themselves by jumping out. $\endgroup$ – Giovanni Aug 19 '20 at 15:16
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    $\begingroup$ Related: space.stackexchange.com/q/33837/6944 That answer quotes Musk " You know, parachutes don’t work too well and [you can’t have] some standard abort system, and just how do you abort 100 people it’s just not feasible, the key is to make the spaceship itself extremely safe and reliable, and have redundancy in the engines, high safety margins and have [it be] well tested. Much like a commercial airliner. Like they don’t give you parachutes." Basically the same rationale as shuttle, as you say. $\endgroup$ – Organic Marble Aug 19 '20 at 15:20
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    $\begingroup$ @OrganicMarble Your answer/comment is good too. $\endgroup$ – Giovanni Aug 19 '20 at 16:35
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    $\begingroup$ @Giovanni: you are saying this as if it were self-evident, but it is not. In fact, in some sense, Launch Escape Systems are completely anti-logical: you are afraid that rockets aren't safe enough, and your answer is to stick even more rockets extremely close to the human passengers. $\endgroup$ – Jörg W Mittag Aug 21 '20 at 17:57
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    $\begingroup$ @Giovanni: Again, a LES is a rocket. It is a rocket that cannot possibly allowed to fail, that must work 100% under any circumstance with no exception. But, if you can build a rocket that never fails … then you don't need a LES, and if you don't trust your rocket, then "strap even more rockets onto the rocket" is by far not an obvious answer at all. Starship weighs three million pounds. A Falcon Heavy would barely be able to lift it off the ground, an actual LES would need multiple Falcon Heavys worth of rockets. $\endgroup$ – Jörg W Mittag Aug 21 '20 at 18:53
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If Superheavy fails during launch (or even fails to launch in an unsafe way) the Starship itself might well be able to just light its engines and fly a suitable suborbital trajectory to a safe landing spot (assuming it wasn't hit by too much shrapnel). By the time Starship normally separates, it is much too high and fast for anything like a launch escape, so the only contingency left is that Starship itself catches fire, or similar, on the pad, or early in the flight, despite the fact that its engines haven't lit up yet. That might reasonably be considered a low enough risk to live with.

They could also fly each new Starship unmanned to orbit and back, as a proving flight if they choose to, which should shake out most manufacturing defects.

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  • $\begingroup$ Although it occurs to me that Starship lighting its engines to get away from Superheavy close to the pad might not be too healthy for the pad. I imagine a fast fire with a full Superheavy propellant load would be something to see -- from a distance! $\endgroup$ – Steve Linton Aug 19 '20 at 16:24
  • $\begingroup$ Thank you. You may want to include Organic Marble's citation of Elon Musk from above into your answer. $\endgroup$ – Giovanni Aug 19 '20 at 16:36
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    $\begingroup$ Well, big liquid-fuel rocket engines with turbopumps (like Raptor) have some startup time. So in case Falcon Superheavy rocket explodes on pad I doubt it'll be enough time for Starship to fly out. In flight phase - maybe. Are there any links this variant was ever considered by SpaceX? Afaik - Elon Musk told about Starship+Superheavy like a commercial airplane analog - it will have no escape system but should have low probabiliy of fatal failure. $\endgroup$ – Heopps Aug 20 '20 at 8:00
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You are not the first to raise this question! It's worth reviewing Tim Dodd's accessible and detailed evaluation of escape systems: https://everydayastronaut.com/starship-abort/

He draws attention to a number of considerations:

  • escape systems are not a panacea.

So in the grand scheme of things, to date, a mechanical abort system has only saved lives twice, may have prevented one tragedy and in one case caused a death. So out of the 320 orbital human flights to date, only three missions in total necessitated the use of an abort system, or less than 1% of crewed launches.

(And to paraphrase one commenter: if our concern is around the reliability and stability of rockets, it is ironic that our solution is "lots more rockets!". There are significant concerns about a) putting powerful, hair-trigger rockets and their fuel right next to the passengers, b) difficulty of testing, c) risks around carrying said rockets back through re-entry.)

  • the Challenger Shuttle disaster fatalities were caused by a series of failures at many levels.

perhaps the biggest problem with the Challenger disaster wasn’t a hardware problem, but a problem with program management and pressure to get that flight off the ground. It was known that they would be launching outside of the predetermined operating envelope of the SRBs and it was recommended to not launch that day.

(Of course, it doesn't matter what the cause of the failure is if you need to escape! But the big lessons lay elsewhere.)

  • trust is earned.

So that’s why I think it’s vital we see these things fly, fly often, and fly over and over. Only then will I think there’s a proven reliability record that would make it a safe enough option to not have an abort system.

A point that I think is rarely made, is that commercial airliners don't need escape systems because we can perform acceptance tests on them. Airliners are taken on test/commissioning flights before and during delivery to their customers, where their airworthiness is evaluated and certified.

You can't do this with disposable rockets: every flight is a maiden flight! And this doesn't exclude the Space Shuttle here, as the extensive refurbishment required after each flight would absolutely qualify for a test flight, if it were airliner, before passengers were allowed on board.

But with cheaply reusable and autonomous rockets, it's a completely different story. By specifically targeting low-maintenance and minimal refurbishment, SpaceX can do test flights and cargo flights until all the hardware and procedural issues are ironed out and the Starships can launch with an airline level of confidence. It is this capability that is unprecedented, and which is unsettling the established view of launch safety. Of course, they may fail in this goal, but that's why the whole grand saga has become so exciting lately!

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  • $\begingroup$ Still it would be safer to have a launch escape tower, or parachutes, or both. (-: $\endgroup$ – Giovanni Aug 21 '20 at 18:06
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    $\begingroup$ A launch escape tower that can lift Starship to safety would be multiple Falcon Heavy worth of rockets. $\endgroup$ – Jörg W Mittag Aug 21 '20 at 18:55
  • $\begingroup$ @giovanni Done properly you only add things that make things safer overall. Most safety system kill people en.wikipedia.org/wiki/Airbag#Injuries_and_fatalities. If adding launch escape system means people die in landing accidents from leaking fuel or inadvertent operation then it is a net loss. Ideally yes, you design your overall system so that it has abort modes but in some cases you come up against physics that mean your choices are not 'do people die' but 'how many people die'. Note of course the key part of this statement is 'done properly' not 'done for profit'. $\endgroup$ – GremlinWranger Aug 21 '20 at 23:40
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    $\begingroup$ … of about 4:1, which sounds barely enough for a LES. So, you would need something as complex as a Saturn V first stage, or multiple Space Shuttle SRBs to even have a hope of getting Starship to safety. (And in all my calculations in all my comments so far, I have always assumed that the weight of the LES is 0, which is of course unrealistic, so an LES would in reality need even more thrust, because it not only has to lift Starship but also itself and its fuel.) Just es a point of comparison: Crew Dragon has 8 SuperDracos. Starship would need 125(!!!) just to hover, and probably up to 1000 … $\endgroup$ – Jörg W Mittag Aug 23 '20 at 10:47
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    $\begingroup$ … for an actual escape. The argument that I am making is not that a "Launch Escape System would block the view", the argument I am making is that the LES you are proposing is so insanely complex that, if you were capable of building it, you would also be capable of building a rocket that is safe enough to not need it. Again, the LES you are proposing has the same level of complexity as the most complex and most powerful rockets ever built in the history of mankind. $\endgroup$ – Jörg W Mittag Aug 23 '20 at 10:49

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