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Comment by Piskvorrr | Hacker News Reader

"Shit happens." Both scenarios could have played out with opposite endings (e.g. there have been other debris strikes in previous Shuttle missions, without fatal consequences), with very small changes in inputs.

There's plenty of things to be learned from each, but I don't see anything those incidents would have in common, except "IN SPAAAACE!".

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The debris collision happened about 20km up, and the orbiter began to break up at an altitude of around 70km (on the way back down, of course), so teeechnically speaking neither event happened in space.

Man, my inner nitpicker really came out on that one.

There is no clear boundary of the atmosphere, so technically speaking no event ever happens in space.

Actually we've defined a boundary at 100km https://en.m.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line

Yep, just because there's no clear physical boundary doesn't mean there isn't a clear line separating "in space" from "not in space."

It is a surface, not a line :)

And it isn't very clear either, since the sea level isn't very well defined as it changes all the time :)

Heh, you're doing it again! The actual water level is constantly changing, but "sea level" is typically defined to some fixed level. Although there is more than one definition to pick from.

Yes, and I can continue until you run out of definitions to cling to :)

Sea level is (presumably) defined in terms of the center-of-mass of the Earth. This center of mass is constantly changing (even as a side-effect of the rocket moving).

Changes smaller than your ability to measure them don't really matter. Especially when we're talking about being ~30km below the definition's altitude.

And here I thought this was a nitpicking subthread.

Ah yes! But at this point it only works if you're nitpicking over the definition of "clear," since the "in space" bit is now settled.

Right? Maybe I missed a nit!

What they have in common is one is BBC's candidate for "Worst collision in the history of space flight" and the other one is mine.

Agree with your comment on opposite endings for small changes in inputs.

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