Artemis 1 has had several unsuccessful tests. We've seen reports of "hydrogen leaks", "engine failures", "sensor malfunctions", "stuck valves", "fueling problems", etc., none of which sound like things you want to hear when launching a rocket.

Had these launches proceeded to T-Minus 6s (Hydrogen burn off igniters initiated / RS-25 engines startup) irregardless, would the things that caused these launches to be aborted have resulted in the rocket exploding on the pad when the engines ignited?

  • 3
    $\begingroup$ It's not quite clear what you are asking. Do you want to know what would happen if NASA had attempted to launch SLS? Well, we know what would happen, because NASA did try to launch SLS several times (or in some instances attempt a wet dress rehearsal), and what happened was … the countdown was aborted. $\endgroup$ Sep 24, 2022 at 22:30
  • $\begingroup$ @JörgWMittag - Yes. Had they proceeded with the launch ignoring thsse errors. Were they "things might conceivably go wrong" problems or "SLS would have blown up if we'd not stopped problems" $\endgroup$
    – Richard
    Sep 25, 2022 at 5:30
  • $\begingroup$ One of the first issues was a chilldown failure on engine 3. I'm not posting this as an answer because I'm not sure if thr engine actually failed to chill or if it was a sensor failure. If the engine did fail to chill, it could have failed in any number of ways. $\endgroup$
    – Dan Hanson
    Sep 25, 2022 at 17:52
  • $\begingroup$ @DanHanson: It was a sensor issue. The team determined later that every sensor except that single one showed the same values that the three other engines showed, and concluded that the same amount of liquid at the same temperature flowing into the engine, the same amount of liquid at the same temperature flowing out of the engine as with the other three, plus everything around the engine getting cold, yet the engine not chilling, is physically impossible. The only possible explanation is a faulty sensor. Since this particular sensor is only used for monitoring of the chill down but is not … $\endgroup$ Sep 25, 2022 at 22:14
  • $\begingroup$ … used by the flight computers, they can (and will) override / ignore it. $\endgroup$ Sep 25, 2022 at 22:15

1 Answer 1


"Would it have blown up" and "might it have blown up" are two different questions. NASA worries about "might X happen" questions -- a lot. "Would X happen" questions are easy to address in comparison.

"Might X happen" questions are a lot tougher to deal with. With those "might happen" scenarios there has to be a tolerance threshold where "might happen" still means "go". By way of analogy, consider your car. I have yet to buy a car, new or used, where everything was perfect, and yet I still used it. With one, it didn't always start on the first try. I eventually got rid of it when it wouldn't start even after three or four attempts. But I lived with the failure to start on the first attempt because it almost inevitably started on the second attempt -- until it didn't. The point of the above is that we learn to live with minor problems, but maybe not major problems.

In the case of "might blow up", the consequence is always a major problem. The question then becomes one of probabilities. Is a million chance of a major catastrophe such as "blowing up" deemed to be okay? (NASA is nowhere close to the one in a million chance of a major catastrophe.)

If that low probability of a catastrophe is okay, what about a one in a thousand chance, a one in a hundred chance, et cetera? A one in one chance would be a "would happen" event. Anything short of that is a "might happen" event.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – Rory Alsop
    Sep 25, 2022 at 21:44

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