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CRS-3 1st stage ocean "landing" video
- Thread starter Mario Kadastik
- Start date
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- SpaceX
Ooo baby! Now that is what I'm talkin' about! We get to see the whole sequence today too. It is awesome that we can see the actual wave tops! The landing legs look like a big set of fins when they are deployed which is why they were critical for preventing spin.
chickensevil
Active Member
Well not as good as I'd hoped but you get enough to let you know it was successful. Telemetry said it reached zero velocity so it is a complete win for reusability. Leftover questions for me are how much fuel was left? How long did it maintain zero velocity? How high above the water did it achieve zero velocity?
Damn. More waiting until the next attempt.
Damn. More waiting until the next attempt.
Skotty
2014 S P85 | 2023 F-150L
I was hoping the video would be better, but something is better than nothing. I'm looking forward to the next launch; hopefully conditions will be better.
chickensevil
Active Member
Damn... that's unfortunate... because it really does look almost completely worthless. What happened that messed the camera up so badly? was it the minor reentry that heated up the camera or something? I didn't think stage 1 went nearly that high into the sky to have that be an issue... Hopefully someone with some leet skillz can make something out of this.
More like bad telemetry reception. The data was probably lost to noise. Spacecraft was probably too low for clear reception.
Wow, nearly useless except for a few partial frames. Too bad, but it doesn't matters what counts is that we know the stage achieved and held zero velocity in a stable vertical position for long enough to demonstrate that a touchdown on land is the next step!
The video is low quality, but still pretty cool.
I'd really like a full length vid, though. I mean real time video from launch, to engine cut, to stage separation, ballistic flight, engine restart, leg deployment, hover, and splashdown all from the save POV.
(Again similar to the videos NASA put out for the Shuttle SRBs.)
I'd really like a full length vid, though. I mean real time video from launch, to engine cut, to stage separation, ballistic flight, engine restart, leg deployment, hover, and splashdown all from the save POV.
(Again similar to the videos NASA put out for the Shuttle SRBs.)
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chickensevil
Active Member
Don't think there is a space rated GoPro yet!
Video had to go via a telemetry link, where the video was secondary to the actual mission data. I image had they been able to recover the booster there would have been much better video of the splash down!
Work on reconstructing the video is coming along pretty well:
SpaceX Falcon9 First Stage (Booster) Landing - home
I also read a pretty good explanation of what exactly they're doing to try to fix the video:
SpaceX Falcon 9 v1.1 CRS-3 Splashdown Video Repair Task Thread
SpaceX Falcon9 First Stage (Booster) Landing - home
I also read a pretty good explanation of what exactly they're doing to try to fix the video:
SpaceX Falcon 9 v1.1 CRS-3 Splashdown Video Repair Task Thread
Hi guys,
I would like to explain what we are actually doing. Because some of you might not completely grasp it. And I think I can best explain it by an illustration. Otherwise it gets too technical too quickly. I will do it in terms of rockets.
--
Imagine a book. A thick book. It's a book containing very detailed technical instructions on how to build a new type of rocket. It contains 13 chapters. One for each rocket part. Each chapter consists of an introductory paragraph explaining what the part is, how it should look like and how it works. None of the following paragraphs can be understood if this paragraph has not been read. The following paragraphs are highly dependent on each other: if you haven't read them in sequence they will be meaningless since they always refer heavily to the previous one to understand.
All sentences are written in a foreign language. And all punctuation is removed. Also all capitals are made lower case. The letters in the words are coded: each letter can only be decoded if you know the previous letter. For example this code: when reading a letter add the letternumber (a=1, b=2 etc) of the previous letter to this one to get the real letter. All whitespaces are removed. So each paragraph is just a string of seemingly random letters.
Ok. Now you're thinking: "This is insane. Who would read such a book?"
But this book was never intended to be read by a human being! It was supposed to be read by a machine that would also automatically build the rocket parts. Here is the real problem though: the printing machine that printed the book had a major error: it sometimes printed the wrong letter! So the book has thousands of random errors in it! Unsurprisingly when the book is now given to the rocket-part-building-machine it says: "Error". And that's basically it.
Ok it turns out that the rocket-part-building-machine made a few incomplete and defective drawings of parts before giving the error. Mostly useless. So it seems that this is impossible to fix. Trying to figure out which letters are randomized by hand is insanely hard and time consuming.
What we did though was the following: instead of fixing the book we changed the machine so it would (1) give us better errors and (2) allow us to overrule certain instructions. We fed the machine with the first paragraph of a chapter and it started to draw the part. When we thought it went wrong we gave it the instruction to skip that portion of the drawing. Because apparently it had read a wrongly printed letter.
Of course we did not know how far it had to skip. So we guessed several times and hoped it would start drawing something sane again. And each time it was drawing something that looked sensible we knew it was reading uncompromised letters. We got an understanding which parts of the paragraph were wrongly printed and then mostly avoided them. By doing this many times and collaborating with several people we have now been able to let the machine draw several almost complete and fairly accurate parts. We do not know yet if it is going to be possible to let the machine read the other paragraphs in the chapters (they are much harder). But getting these drawings is already very satisfying.
--
I hope this illustration helps you (who might not understand the deeply technical stuff) to understand what the problem really is. How insane it is. And I think it's a quite good representation of what is actually the case.
Regards,
arnezami
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PS. Below is a translation from the illustration into the real problem.
- Book: Video
- 13 chapters: 13 parts of the video
- First paragraph of each chapter: I-frame (independent picture)
- Other paragraphs: P- and B-frames (all dependent on each other)
- Foreign language: the language of video decoding (things like "discrete cosine transform", "motion vectors", "chrominance and luminance blocks" etc)
- Removal of punctuation and capitals: there are essentially no clear "markers" in the bitstream: no marker to detect the beginning of a horizontal line in the picture.
- Words: macroblocks (16 x 16 pixel blocks)
- Letter coding and removal of whitespaces: the coding of the bits is such that you need every previous bit to know what the current one means withing a word. The words are also variable in length. There is essentially no clear marker between each macroblock.
- Printing errors: random bits that were flipped due to bad reception
- Rocket-part-building-machine: the video decoder (the open source ffmpeg in our case)
- Drawings: the pictures the video decoder makes after trying to decode a frame
The transportstream is not mentioned. But effectively many pages of the book were missing. We mostly fixed that: they were actually "hidden" and we discovered most of them.
chickensevil
Active Member
I love the open source community <3
They have made some pretty great progress on those 13 frames! The best SpaceX was able to provide previously was like 2 partial frames that looked somewhat discernible. I hope that SpaceX ends up doing something special for these people who contributed.
They have made some pretty great progress on those 13 frames! The best SpaceX was able to provide previously was like 2 partial frames that looked somewhat discernible. I hope that SpaceX ends up doing something special for these people who contributed.
I have unfortunately not had enough time to properly parse through all of the glorious information on the NSF forum, but I never realized that the legs deploy so soon before "impact" I would have thought they would be out long before the landing to increase aerodynamic drag.
Cannot believe how much they've improved the video. Was reading some of the thread on NSF, simply mind-boggling.
Cannot believe how much they've improved the video. Was reading some of the thread on NSF, simply mind-boggling.
That was my thinking too, but now that I've seen them, I think deployed they'd add too much asymmetric drag at speed.
anticitizen13.7
Not posting at TMC after 9/17/2018
Major props to the people who repaired the video! It's amazing to watch the landing legs deploy and the rockets fire as the Falcon 9 slowly approaches the water.
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