SpaceX’s Failed Landing Still Ended With a Clean Plop


EXCERPT: . . . SpaceX launched its 20th rocket of the year (CRS-16 mission) just two days after lofting a record 64 satellites into orbit. On this flight, a brand-new Falcon 9 hoisted a Dragon spacecraft into orbit, bound for the International Space Station. But unlike Monday’s textbook touchdown, today’s landing didn’t quite go as planned.

The Falcon’s first stage, the largest and most expensive portion of the rocket, was expected to navigate itself back to land after launching the Dragon spacecraft. But instead of gently touching down in the middle of SpaceX’s designated landing pad, the booster made an unscheduled plop into the Atlantic Ocean, just off the Florida coast. Video footage shared shortly after the incident shows the booster spinning out of control as it headed towards land.

But what caused the the anomaly? SpaceX officials will need to examine the booster to find out, but [...] SpaceX founder Elon Musk tweeted soon after the rocket landed. "Appears to be undamaged & is transmitting data. Recovery ship dispatched."

Musk indicated that it’s possible that SpaceX may be able to use the booster after fishing it from the ocean, tweeting that it could be used for an internal SpaceX mission. [...] But others at SpaceX are more circumspect [...saying...] it’s too early to tell if the booster is salvageable. [...] Today’s mishap marks the first time that the Falcon has failed to stick a landing on solid ground since SpaceX began recovering boosters. But it’s far from a failure. The incident instead illustrates how the rocket is designed to save itself in case something does go wrong....


VIDEO (of CRS 16 launch):
Watching the SpaceX TV stream, you knew that something had gone wrong when the video from the returning booster started spinning in a violent roll right before landing burn ignition. SpaceX cut away and the video switched to the second stage which was performing flawlessly.

On his twitter account Elon Musk said that they should have continued playing the video from the failing booster and that he'd get the missing footage and put it online.

Musk seems to think that what went wrong was a failed hydraulic pump that powers the 'grid fins', those aerodynamic steering vanes that look like waffle irons. You would think that hydraulic pressures would be the kind of engineering telemetry that's either recorded onboard or radioed to the ground, so it should be easy to verify.

Here's the on-board video from the booster

The grid fins don't appear to be moving. And they aren't stuck in a neutral position either. They appear to have frozen in a position where they are forcing the vehicle to roll. It looks like that forced roll only stops when the vehicle's movement through the atmosphere has decelerated enough that the fins no longer exert strong aerodynamic force.

The roll must screw up the whole landing process since the rocket largely controls itself by gimbaling the engines so as to vector rocket thrust in desired directions. That would seem to be impossible if it's rolling. It's obvious from the ground shots that it was having great difficulty controlling itself, even though it was desperately trying. (It's so easy to anthropomorphize robots.)

And here's that view from the ground

Apparently the water landing is a feature, not a bug. Reportedly the boosters steer themselves at a point in the water near the landing pad, precisely because if something goes wrong, people don't want tons of explosive rocket coming down on Cape Canaveral's heads. So it aims at a safe point in the water, then changes course towards the nearby landing pad late in its descent during its landing burn.
Elon was trying his pot and whiskey fuel. Makes rockets spin just as well as rooms.
Yesterday's supply flight to the Space Station was unmanned, but it did carry living astronauts. 40 of them! Old mice, mouse senior citizens.

Part of an experiment to assess the effects of zero G on the physiological effects of aging.

The launch was originally scheduled for Tuesday but had been pushed back to Wednesday. Why? Moldy mouse food!! (Eeewww!) It's true, it had to be replaced in the Dragon capsule.
Very nice NASA photo of the SpaceX Dragon supply capsule arriving at the Space Station. (Extra-credit if you can identify the land below.)

[Image: blog_iss056e073506.jpg]

And here's a short NASA video from inside the Space Station showing the recent Soyuz capsule hatch opening and the arrival of three new astronauts on the Station.
South Korea?
(Dec 11, 2018 07:29 AM)Syne Wrote: South Korea?

Too narrow and the scale is wrong.

(Dec 11, 2018 07:11 PM)Secular Sanity Wrote: Crete.

And SS is the big winner! The Space Station was passing over Greece when the Dragon capsule arrived.

When I first looked at it, I guessed Greece, but thought that it looked like the Mt. Athos peninsula in northern Greece. But NASA says it's Crete.
For some reason my initial thought was Greece, but when I went to look at a map, the orientation threw me.

Bravo to the geography buffs.

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