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Comment by cconcepts | Hacker News Reader

I would have assumed that you could calculate the approximate landing area of at least the larger debris and that there would be some legislation forcing you to at least try to locate/clean it up.

I suppose it doesn't present that much of a threat to anyone (once it has landed).

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Most expendable launchers are just dropped into the ocean anyway. SpaceX is the only company that has plans to completely recover the first stage.

I can also assure you that they did do everything they could to locate and recover the debris from this launch. But for some altruistic environmental concern though ... They wanted every piece they could find so they could figure out what happened.

EDIT: Based on analysis from /r/spacex, this is from CRS-4 (not CRS-7), which successfully boosted its second stage, then performed a retropropulsion to test rentry (it didn't have landing legs, so a barge landing couldn't be attempted). I suspect SpaceX still tried to recover as much as they could of the stage, in order to see how well it handled the rentry.

Don't you mean: But NOT for some altruistic ...

Indeed I do, thanks (the danger of typing on mobile... linebreaks are common and proofreading is hard).

Blue Origin just demonstrated a recoverable rocket. But their ambition is just suborbital which only needs 1/8th the power or orbital flight.

I believe Blue Origin and Virgin Galactic are both planning for reusable orbital launchers. They're pretty far out from flying, though. I think SpaceX is the only one actually putting stuff into orbit with concrete plans for reusability.

Yeah, by "launcher" I meant "rockets that can put things into orbit".

New Shepard is cool and all, but it's not really in the same weight class as "real" launchers.

https://i.imgur.com/g2VIKVC.jpg

Theoretically, sure, but practically the amount of turbulence experienced by a supersonic rocket (all of them, except those that blow up in the first 10-30 seconds after lift off) is just insane. Any sort of errors that you would have in the calculation describing the initial explosion (already largely unknown because it's an uncharacterized/unstudied catastrophic failure) would only compound over and over again for minutes until they hit the earth. Most rocket pieces are very dense, like all of the high pressure & cold temperature fuel storage and distribution, and those that don't vaporize tend to have a very high terminal velocity, some even supersonic themselves, adding more turbulence to the calculation. Most catastrophic failures also happen with a decent amount of propellant so there's now a low pressure (less than 1 atm) explosion fueled by literally tons of volatile high pressure liquid which creates even more uncertainty. Oh and hey, since the rocket carries all of its own oxidizer, the explosion usually isn't limited by the availability of atmospheric oxygen.

Simply put, every step in this chain of events is mind bogglingly chaotic and nondeterministic. You can create boundaries for how far the pieces could have possibly traveled using assumptions based on the laws of physics, but even at an altitude of 10km, perfect GPS pre-failure, and subsonic speeds we're talking about an area tens of kilometers in radius before you account for ocean currents that quickly expands to an area that is hundreds of kilometers in radius. All of this happens before the first search ship is even in the area (fastest boat is about 100km/h and that's a racing yacht incapable of search and recovery). This truly is an intractable problem until we have radar covering every cubic kilometer of the earth, and even then it'll still be really difficult.

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