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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. $\endgroup$ 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. $\endgroup$ 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. $\endgroup$ 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! $\endgroup$ 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
  • $\begingroup$ I wonder if the Starship could really escape a Superheavy explosion. Look at the size of that thing. Compare with the Soviet N1 rocket, which when it blew up caused "one of the largest artificial non-nuclear explosions in human history." To evacuate the crew from the blast radius with maybe a split second forewarning the massive starship would need quite an acceleration. $\endgroup$ May 2 '21 at 10:22
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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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    $\begingroup$ A launch escape tower that can lift Starship to safety would be multiple Falcon Heavy worth of rockets. $\endgroup$ Aug 21 '20 at 18:55
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    $\begingroup$ @GremlinWranger A launch escape tower never failed, afaik. It saved the Soyuz T-10-1 crew from death that otherwise would be certain. Not having it led to the death of the Challenger crew which might have been avoided. Ironically, during Mercury-Redstone 1, the LES was the only thing that worked (as well as Mercury's parachute). $\endgroup$
    – Giovanni
    Aug 22 '20 at 5:46
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    $\begingroup$ @SusanW Yeah the Titanic is unsinkable, why put so many lifeboats on it? The huge cost, the delays and efforts, who needs that? And they might block the view. That's your and Jörgs argument. But in case of the BFR, an escape tower would really be not the best emergency system. Better to have such side thrusters like the Crew Dragon has. And parachutes per crew member wouldn't hurt perhaps, and might have saved the lives of the Challenger crew. $\endgroup$
    – Giovanni
    Aug 22 '20 at 18:05
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    $\begingroup$ @Giovanni You misunderstand the argument, and I doubt that can be fixed in these comments. And, "block the view"? It seems you are now just indulging in ridicule, and this discussion is not productive. Believe what you like, and feel free to downvote if you feel the answer is wrong. $\endgroup$
    – SusanW
    Aug 23 '20 at 9:16
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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. $\endgroup$ Aug 23 '20 at 10:49

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