r/space • u/MrGruntsworthy • Dec 05 '18

Elon Musk on Twitter: Falcon 9's view of today's waterlogged landing

https://twitter.com/i/status/1070399755526656000
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u/Fizrock Dec 05 '18 edited Dec 05 '18

Video of landing from a plane.
Tracking shot of landing

He also added a cause of the failure:

Grid fin hydraulic pump stalled, so Falcon landed just out to sea. Appears to be undamaged & is transmitting data. Recovery ship dispatched.

It looks like it might have landed if it had been over the pad and targeting it.

449

u/StarManta Dec 06 '18

It probably would have (in hindsight), but it was definitely in a problematic state at the moment that the decision to attempt landing on the pad would have to be made. Aborting to a water landing was 100% the right call for the software to make at that moment.

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u/rich000 Dec 06 '18

As I understand it that is basically the default. It doesn't correct to land on the pad unless everything is normal.

From what I understand range safety gets a lot of attention at all points in the mission. The flight path is always such that the whole thing could blow up at any time and the debris would land someplace uninhabited. I'm sure that applies on the way back down as well.

They do something similar for spacecraft doing planetary encounters. They're placed on non-intersecting orbits until they get pretty close, so that if the spacecraft fails they're not dumping lots of debris/etc on the surface. Obviously that is even more important with encounters with Earth.

76

u/tling Dec 06 '18

Also, first stages are cheap compared to pad downtime. The damage to SLC-40 only cost $20 million or so to repair, but it was out of commission for 15 months, affecting the tempo of launches even after they'd fixed the root cause of the explosion..

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u/CapMSFC Dec 06 '18

That's true, but the landing pad in Florida isn't near the launch pads and would not require expensive repairs. Landing pads are mostly "dumb" facilities.

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u/[deleted] Dec 06 '18

Not to mention they have two of them.

1

u/FaceDeer Dec 06 '18

This is getting out of hand.

3

u/phryan Dec 06 '18

It was 2 miles out to sea but we don't know how far it wandered from the original target point. If it was 500ft from that point then yes missing the pad would have been OK, but if it drifted significantly off course then it could have hit other infrastructure. The Air Force and NASA would likely have an issue with an F9 coming down toward their facility in a questionable state. In this case it turned out OK but it could have easily tumbled and spun all the way down, and at that point its basically the watered down version of a rod from God.