[SyzygyRhythm]

It's the original definition of "pushing the envelope." You start with a known flight envelope, then push a little past that. Sometimes you learn that the real envelope is bigger than you thought. Other times you find that the envelope is exactly where you thought it was.

[timschmidt]

I notice I mis-typed and should have said you can't overstate the importance of Starlink on the development program. And I agree with you about pushing the envelope. It was really interesting to hear that they were planning on testing an engine-out scenario with this booster by lighting one of the middle 10 engines and two centers. If they can pull that off, they'll have a measurable increase in fault tolerance over Falcon 9.

[__m]

is igniting the engine pushing the envelope though?

[SyzygyRhythm]

We don't know all the things they did to the Booster, but among them were deliberately not igniting some engines as well as taking a more aggressive angle-of-attack on descent (the rocket is a fairly effective lifting body, as it turns out!).

There may be more things, but between those two I think the latter was a bigger problem. It would have gotten hotter and more physically stressed. And then weakened to the point to where re-igniting the engines caused it to fail.

They also used a new hot-staging maneuver, where the gases were directed out one side so that it flipped more rapidly in the other direction. It was a really fast flip! A rocket the size of a small skyscraper turning 90 degrees in just a few seconds. That could have jarred something loose, too.

Hopefully we find out in the post-mortem. SpaceX doesn't typically give the public as much detail as we'd like, but they're pretty good at sharing the high-level reasons why something failed.

[hoseja]

>SpaceX doesn't typically give the public as much detail as we'd like

It gives magnitudes more details than anyone else.

[vardump]

ITAR unfortunately limits what can be publicly released.