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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).

https://space.stackexchange.com/a/46080/36625

Is it normal for upper stages to survive having a lower stage go boom beneath them? Are there any recorded instances of sn upper stage emerging unharmed (only to be destroyed by the fall/range safety)?

Abdullah is not an Amalekite
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    A fail of a lower stage is not necessarily an explosion. – Uwe Apr 16 '23 at 17:45
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    Starship is a special case because its upper stage is designed to work at sea level as well as in vacuum. Most upper stages could only pull this trick off if it were already very near to the end of the first stage burn already. Then they have to worry about where they'd escape to. – Infinite_Maelstrom Apr 16 '23 at 21:48
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    There is another big problem here--most rockets can't survive a fire in the hole ignition. The upper stage exhaust hits the lower stage and bounces back. The only space rocket that I'm aware of that could survive this is the Apollo lunar lander--and that was done by arranging things so there wasn't much in the way of the upper stage exhaust. – Loren Pechtel Apr 17 '23 at 00:17
  • The cargo capsule for CRS-7 could have survived if it had triggered its parachutes, because it was designed for a full orbital reentry and splashdown at sea. And of course capsules with escape systems are designed in the hopes that they'll do their job in such an event, though I think all actual instances of their use have been with less violent failures. These are rather specialized "stages", though, particularly well equipped for surviving after being thrown into the atmosphere on their own. – Christopher James Huff Apr 17 '23 at 00:37
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    A loss-of-mission failure of the lower stage is propbably going to leave it tumbling or exploding, or most likely both. LES usually takes the crew capsule away at 10+ g acceleration, while an upper stage might not even be able to produce 1 g at ignition (though obviously Starship could). A relatively benign failure might be survivable for an upper stage, but that's going to be a rare case. – Russell Borogove Apr 17 '23 at 04:37
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    @LorenPechtel many Soviet boosters use(d) fire-in-the-hole ignition as did some US Titans. https://space.stackexchange.com/q/5187/6944 – Organic Marble Apr 17 '23 at 13:25
  • "upper stages fire and escape" - is normal and even required procedure for a crew cabin. It has never been used during catastrophic failure on a launch pad but it did save the russian-americal crew during Sous inflight 1st stage failure. – TheMatrix Equation-balance Apr 21 '23 at 04:12
  • There have been many cases that the lower stage failed (shut down early) so the upper stage has to start early and burn for longer. Chinese CZ-5 Y1 is one that I know of. Y2 also suffered an early shutdown of 1st stage but the upper stages didn't quite save it. – user3528438 Apr 21 '23 at 05:38
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    @TheMatrixEquation-balance Titov and Strekalov beg to differ https://en.wikipedia.org/wiki/Soyuz_7K-ST_No.16L – Organic Marble Apr 28 '23 at 22:16
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    @OrganicMarble - "the escape system motor fired, dragging the orbital module and descent module, encased within the upper shroud, free of the booster with an acceleration of 14 to 17g" - OUch! – TheMatrix Equation-balance Apr 29 '23 at 15:54
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    @TheMatrixEquation-balance I worked with Titov on STS-86. His story of the incident was awesome. – Organic Marble Apr 29 '23 at 16:15
  • @OrganicMarble - Wow, you are really touched by the history of space exploration. – TheMatrix Equation-balance Apr 29 '23 at 16:37

2 Answers2

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Other than "upper stages" in the form of launch escape systems, I'm not aware of any actual cases of a rocket firing an upper stage in response to a lower stage failing. However, there have been cases, most notably the fourth attempt at launching the N-1, where post-failure analysis noted that activating an upper stage in response to a lower stage failing could have salvaged the mission.

It's important to note that most "rocket blowing up" pictures you see aren't showing the actual failure. The actual failure would have been something much smaller (such as a guidance-system failure or an engine catching fire), and the bigger explosion is a deliberate rupture of the fuel tanks to prevent them from crashing down somewhere.

Mark
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  • Missed Apollo 6. Third stage failed to ignite. SM engine was used to make orbit. It's kind of like another stage. – Joshua Apr 26 '23 at 01:42
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    @Joshua, according to the Wikipedia article, it was the second ignition of the third stage (to perform the trans-lunar injection) that failed. The SPS engine was used to put the spacecraft into an orbit that would complete some but not all of the mission objectives. – Mark Apr 26 '23 at 02:43
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I believe most upper stages that rely on supercooled liquid fuels perform a pre-chill of the fuel/oxidizer pumps before firing to keep them from overheating when spinning up. This is based on every Falcon 9 launch mentions the precool of the upper stage engine taking place quite a few seconds before stage separation and 2nd stage ignition. I would guess that if there were a catastrophic failure of the 1st stage, there wouldn't be time to initiate the precool for proper firing. If it were a solid fuel upper stage, I suppose this could be possible, but I believe solid fuel upper stages are pretty uncommon for a variety of reasons.

I'm pretty confident (though don't have the data handy to back it up) that all emergency escape systems are solid-fuel for instant firing capability to get the important cargo (i.e. humans) away as quickly as possible and not have to wait for any prechill.

Milwrdfan
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  • Solid-fuel escape systems are the most common, but there are several capsules that use hypergolic engines instead. There are also non-cryogenic upper stages (hypergolic or otherwise) that don't need pre-chilling, and upper stages that start pre-chill on the ground. – Mark Apr 26 '23 at 02:31