
NASA, SpaceX Share Data on Supersonic Retropropulsion - elektropionir
http://aviationweek.com/space/nasa-spacex-share-data-supersonic-retropropulsion
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lscharen
"The two midwave IR sensors—mounted in a nose pod on the WB-57 and internally
on the P-3—were about 60 nm from the rocket when it reignited its engines for
supersonic retropropulsion."

They clearly mean Nautical Miles (nm) here, but I did a double-take on my
first read through.

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worklogin
Nautical Mile is shortened to NM, or nml.

-DDG

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clebio
> That produced raw images in which the stage appeared 1 pixel wide and 10
> pixels long, but subsequent enhancing by specialists at the Johns Hopkins
> University Applied Physics Laboratory improved the resolution dramatically.

So, the final resolution was something like... 10x100 pixels? How do you
enhance a 1 pixel image? I'm guessing the two aircraft, at two different
altitudes, help ... you get 2 pixels instead of 1.

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smoyer
It's (probably) an unstable video, so you take the data from each frame for
some large fraction of a second and you can create an image that's somewhere
between the total number of available pixels in all the frames and the number
in a single frame.

Note: While the spacecraft itself is moving at incredible speeds, the
maneuvers themselves are slow enough that several (to many with a high speed
camera) images can be combined.

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ChuckMcM
SpaceX got a lot of help from NASA, especially in regards to pintle engines[1]
and this seems like a great way to pay back that transfer of expertise by
moving the ball forward. My assumption (clearly incorrect) was that descent
could be managed subsonically as the vertical speed at apogee is 0 but of
course that stage has been pushing the second stage into its position and so
it travelling down range at several k/s. Presumably you could deploy some sort
of upper drag system which would use atmospheric drag to reorient the stage
but you still have the fact that its travelling super sonically when you light
the engines. I would love to see the CFD simulation of a exhaust nozzle when
going that fast backwards! And then you light it off! I really hope that at
some point they figure out how to glue a camera on to that stage so we can see
what that looks like.

[1] [http://blog.nss.org/?p=1900](http://blog.nss.org/?p=1900)

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smoyer
"Data-sharing deal will help SpaceX land Falcon 9 on Earth and NASA put humans
on Mars"

I find the sub-title a bit ironic as (right now) I'd bet that SpaceX
astronauts will beat NASA astronauts to Mars.

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melling
Hard to say and kind of irrelevant. The ideal scenario is that they both make
it. In fact, if China and Russia could do it, that'd be even better.

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kivihiinlane
I'm curious, why is it better if Russia and China do it first?

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smoyer
I believe @melling implied that it would be better if Russia and China could
_also_ get humans to Mars.

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bhhaskin
The U.S. is just so far ahead in terms of space technology. I am sure one day
other countries will catch up, but it is going to be awhile.

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angersock
It's a matter of will, not necessarily of tech. The US has shown it lacks the
will to achieve its former dominance.

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BrandonMarc
This video shows IR footage from one of the planes:
[https://www.youtube.com/watch?v=_UFjK_CFKgA](https://www.youtube.com/watch?v=_UFjK_CFKgA)

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martinwastaken
I enjoyed Elon's interview on TED. Just when it starts sounding like he's
smoking a dream-pipe about recycling rockets, he shows a clip of a test
landing. Early days, but it's amazing. I agree with @smoyer, the guys at
SpaceX are ninjas, I wouldn't be surprised, because they're making insane
advances in a relatively short time-frame. Can't wait to see what they do
next.

