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SpaceX: “Close, but no cigar. This time”

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Re: SpaceX: “Close, but no cigar. This time”

#12
post #4

Cool video! Just what we've been waiting to see. I wonder what actually exploded there? Part of the argument for why the landing was supposed to be relatively safe was that the stage would be mostly empty of fuel by the time that it landed, so there wouldn't be much to explode if something went wrong. So is that an explosion of the remaining fuel in the rocket, or something on deck?

It doesn't take much to make the kind of explosion you see in the video (those chemicals are quite volatile). I think the safety comes from that being the extent of the explosion. Compare that to a fully-fueled stage, which would have 90x more fuel, a 90x larger fireball, shock wave, etc.

The deck of the ship almost looked undamaged!

Re: SpaceX: “Close, but no cigar. This time”

#13
post #4

Cool video! Just what we've been waiting to see. I wonder what actually exploded there? Part of the argument for why the landing was supposed to be relatively safe was that the stage would be mostly empty of fuel by the time that it landed, so there wouldn't be much to explode if something went wrong. So is that an explosion of the remaining fuel in the rocket, or something on deck?

"Mostly" != "entirely". Also, don't forget the rocket engine itself

My guess would be the explosion was of the remaining fuel in the rocket engine and tank. Either that or it wasn't actually an explosion, just burning fuel-air mix spewing about after the rocket nozzle deformed too much.

Re: SpaceX: “Close, but no cigar. This time”

#14
post #4

Cool video! Just what we've been waiting to see. I wonder what actually exploded there? Part of the argument for why the landing was supposed to be relatively safe was that the stage would be mostly empty of fuel by the time that it landed, so there wouldn't be much to explode if something went wrong. So is that an explosion of the remaining fuel in the rocket, or something on deck?

That was pretty small and safe as rocket explosions go. Launch pad explosions with a full load of fuel and oxidizer are huge and would have engulfed the whole ship in flames.

Re: SpaceX: “Close, but no cigar. This time”

#15
post #4

Cool video! Just what we've been waiting to see. I wonder what actually exploded there? Part of the argument for why the landing was supposed to be relatively safe was that the stage would be mostly empty of fuel by the time that it landed, so there wouldn't be much to explode if something went wrong. So is that an explosion of the remaining fuel in the rocket, or something on deck?

From this tweet, it looks like it was the residual fuel:

https://twitter.com/elonmusk/status/555980855537975296

Re: SpaceX: “Close, but no cigar. This time”

#16
post #8

Looks like it did not come down vertically but at a slant, but they got the positioning better than I thought they would on this try. One thing to note is that it is from now on officially a very bad idea to piss off Elon Musk if he knows where you live, being able to hit stuff with this kind of accuracy using rockets from space is normally enough to get you placed on the 'axis of evil' list. Incredible precision.

You joke but a future were corporations control ICBMs to their advantage is a realistic worry.

Re: SpaceX: “Close, but no cigar. This time”

#17
post #4

Cool video! Just what we've been waiting to see. I wonder what actually exploded there? Part of the argument for why the landing was supposed to be relatively safe was that the stage would be mostly empty of fuel by the time that it landed, so there wouldn't be much to explode if something went wrong. So is that an explosion of the remaining fuel in the rocket, or something on deck?

You need some margin for error to assure that you have enough fuel during the last fuel seconds to hit the marge at a safe speed, this means that there will likely be some fuel left over. In terms of a rocket exploding, that explosion seemed tiny. Compare it to the Antares [1], which exploded just a few seconds after launch.

[1] https://www.youtube.com/watch?v=jHMmMgdcOSU

Re: SpaceX: “Close, but no cigar. This time”

#18
That is awesome! I appears the stage has maybe 10 m/s horizontal velocity and less than that vertical, but at that angle I can see how difficult it would be for just engine gimballing to get get it vertical again. I wonder if the barge is equipped to record a downlink of telemetry from stage. Once it gets close enough you should be able to shoot over at least some data which the barge could presumably keep 'safe' in a blast protected storage system.

Re: SpaceX: “Close, but no cigar. This time”

#19
post #16
post #8

Looks like it did not come down vertically but at a slant, but they got the positioning better than I thought they would on this try. One thing to note is that it is from now on officially a very bad idea to piss off Elon Musk if he knows where you live, being able to hit stuff with this kind of accuracy using rockets from space is normally enough to get you placed on the 'axis of evil' list. Incredible precision.

You joke but a future were corporations control ICBMs to their advantage is a realistic worry.

That's no longer the future. SpaceX is a corporation and that rocket could have been pointed the other way for a bit longer easily.
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