
SpaceX recovery attempt not successful: water landing instead of land - dolfje
https://clips.twitch.tv/embed?clip=CleverSpineyEggPrimeMe
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greglindahl
This twitch video appears to be shot from Jetty Park, so there's a hill in the
way. The people talking in the video can't see that the booster is out over
the water. This is actually what's supposed to happen if the rocket thinks it
has a problem: it's pointed offshore until the middle of the final landing
burn. If it's unhappy, it stays pointed at the ocean.

This video from a plane shows how far offshore it was:
[https://twitter.com/flying_briann/status/1070392207696453632](https://twitter.com/flying_briann/status/1070392207696453632)

And Elon's tweet with SpaceX's video from the booster itself:
[https://twitter.com/elonmusk/status/1070399755526656000](https://twitter.com/elonmusk/status/1070399755526656000)

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Symmetry
Surprised but glad it didn't explode after it fell over. Apparently they plan
to use it for internal projects, which I took to mean the in-flight abort test
of the Dragon.

I seem to recall that the Block 5 is targeting >10 reuses so even if they flub
1 in 20 landings going forward that's far from the end of the world in ROI
terms.

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achamayou
It’s pretty much out of fuel by then, so an explosion isn’t very likely.

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mabbo
There's lots of great videos to prove you wrong on that one, actually.

The most dangerous time for a can of gasoline is when it's just been emptied-
because it's actually full, just of air and gasoline vapor. It's a bomb at
that point if you aren't careful. Rockets? Similar problems.

Watch what happened a few years ago when another Falcon 9 fell over because of
a faulty landing leg:
[https://www.youtube.com/watch?v=xr7GcpFGWd0](https://www.youtube.com/watch?v=xr7GcpFGWd0)

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achamayou
Rockets contain both fuel and oxidiser, explosions when they are full are
considerably worse than when empty. Compare the video you have linked to clips
of Atlas or Soyuz blowing up on the pad.

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mabbo
Too true! The Falcon 9 that exploded on the launch pad certainly proved that
point.

Nonetheless, an empty rocket is still dangerous.

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th0br0
ElonMusk just posted a video of the actual landing - including the fall.

[https://twitter.com/elonmusk/status/1070399755526656000](https://twitter.com/elonmusk/status/1070399755526656000)

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cmsonger
That's a great video, thanks for posting.

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dolfje
Although it didn't land as they wanted, primary mission is still success. Also
the booster is in the sea and still transmitting and will be recovered, but
only be used for internal spaceX missions. Unfortunately the live spaceX
webcast tuned away from the failing booster. But Elon has given his word it
was wrong to tune away.

The issue is apparently with the hydraulics system of the grid fins that had a
problem. It was nice to see that the gimballing engines recovered the spin
before the sea landing.

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vvillena
It's been just 3 years since the first rocket landing, and we're so used to it
to the point that today's mishap will get more coverage than yesterday's
achievement. Seeing the renewed speed of the space launch industry puts a huge
smile on me.

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segmondy
Actually, that was a good "intact water landing" the rocket stopped the spin
before landing, then the rocket positioned itself so it fell horizontal on the
water for retrieval instead of vertical

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TomVDB
Does that mean that it uses some side boosters to ensure that the movement
from vertical to horizontal is controlled?

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ChuckMcM
This is the best video of the failed landing attempt I've seen so far. Elon
tweeted a grid fin hydraulic pump stalled.

I understand for "marketing" reasons why they stopped the video feed from the
first stage but since there wasn't any danger to humans here I was
disappointed that they cut away from that and pretty much went into the damage
control speak of "the primary mission is going well."

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codeulike
Elon's saying they shouldn't have cut away from it. He just posted the rocket-
eye view of the water landing:

[https://twitter.com/elonmusk/status/1070399755526656000](https://twitter.com/elonmusk/status/1070399755526656000)

 _Engines stabilized rocket spin just in time, enabling an intact landing in
water! Ships en route to rescue Falcon._

~~~
DreamSpinner
Although I'm completely unqualified to comment on it, I did notice that the
spin seemed to reduce at the same time the landing legs extended. I'm
wondering if they may have acted like fins and contributed to the countering
of the rotation. If that's the case, it might be that a contingency approach
of a small extension of the legs outwards (only a little) might help.

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lutorm
extending the landing legs will reduce roll rate for exactly the same reason a
figure skater slows down when they extend their arms: roll axis moment of
inertia goes up.

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craftyguy
> SpaceX recovery attempty not successfull: water landing instead of land

Perhaps some mod can fix the typos in the title?

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Latteland
Did they actually have a plan to divert to water if they knew they couldn't
safely land?

They aren't clear about whether it was an accident that they ended up in the
water or was it by design. They could have planned ahead for this situation,
if they detect that they have a problem and can't do a normal safe landing
(the out of control spin) and then they could send it for a 'safe' and
hopefully controlled water landing like they did. Or it could just be that it
was way off course because they couldn't control it and it was just luck.

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darkport
It’s by design. The default for all F9 rockets is to land off-shore in the
water. Once all the checks are complete and the rocket is “happy” and all
systems are performing nominally, it redirects to the landing zone (either a
barge or on land).

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Latteland
That is really cool and makes sense. I continue to be impressed and delighted
by spacex engineering and design.

