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I'm in love with SpaceX and Falcon 9, I watch every live stream and the most special, most amazing, most thrilling part of each launch is the 1st stage landing. Seeing the smoke (or vapor) clear and seeing that 33m tall rocket landed safely within 2 meters of target makes me cheer in my office on the far side of the world.

But for some reason every Falcon 9 landing's live feed from "Of Course I Still Love You" cuts out just as it's coming into view. Why? Oh, why, does does it torture me so?

SpaceX Falcon 9 half a minute after landing I can see it! I can see it right there. But why has the feed dropped out?

geoffc
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Coomie
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3 Answers3

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Consider what is happening. A rocket firing a 175,000 lb thrust engine, (throttled down as low as it can go, so let's call it 100,000 lbs thrust) is pointed at, and getting closer and closer to a flat surface 170x300 feet in size floating on the ocean.

The engine thrust is vibrating the platform so much they lose satellite lock.

To put that in scale: A Boeing 777 engine has 105,000 lbs of thrust; a 747 (depending on the model and engine choice) had around 60,000 lbs of thrust (in each of four engines) and on close approach to the exhaust stream of a 747, it is possible to roll a school bus from the air flow.

The ASDS is shaking very badly due to the rapidly approaching rocket. As it gets closer the effect gets worse.

geoffc
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  • Yes. They said this on the JCSAT-16 webcast. – Hobbes Aug 18 '16 at 05:46
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    How (actually) does shaking cause loss of signal? It can't be just a given, there has to be some mechanism. Is is translation or rotation that causes it? A narrow-beam dish antenna I can see, but if it's a phased array, those in principle could just have feedback from a small electronic gyro. And why can't they just broadcast it 15 seconds later when the vibration stops? A video buffer is not such a hard thing to imagine adding. I don't really buy it that with all this technology that works really really great with vibrations, it's only the public video feed that's affected. – uhoh Aug 18 '16 at 05:56
  • @uhoh Exactly, there are cameras on the Falcon 9 and they don't drop out at all! – Coomie Aug 18 '16 at 07:34
  • @Coomie The rocket is not shaking so much... – Antzi Aug 18 '16 at 07:41
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    @uhoh: Phased arrays are not routinely used for satellite links, so they'd have to engineer a one-off solution. Why would they spend $$$ on a fancy feed that doesn't interrupt, when the primary goal of that video camera is to have a record they can analyse at their leisure? The data is stored on the ASDS for later review. – Hobbes Aug 18 '16 at 07:55
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    @coomie: video feeds on the rocket use an omnidirectional antenna and are relayed to an aircraft nearby. Much shorter signal path = you don't need a dish so less chance of cutouts. Even then ISTR video interruptions and hiccups in past missions. – Hobbes Aug 18 '16 at 07:56
  • @Hobbes Does the vibration shake a high gain dish antenna itself so much that its direction is constantly changing? The ship will be gently rocking by a degee per second (at most) due to surface motion but that could be tracked easily, but ya that kind of sysem couldn't handle multi- Hz random vibrations. Actually these days you really can buy personal phased arrays - electonically steered systems for your sat phone, they wouldn't have to be developed independently. Considering how much I'm paying to watch this, they should... oh wait, this isn't HBO - it's free isn't it. :) OK I'm good. – uhoh Aug 18 '16 at 09:41
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    Satcom dish sticking out above one of the containers, rocket engine exhaust blasting the ship and everything on it, yes the dish is going to move around. – Hobbes Aug 18 '16 at 10:24
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    Something to consider (as an additional motivator, not a primary) is that SpaceX has spent a lot of money on software design and other engineering. It may be to their benefit to not broadcast high quality footage of the most critical portions of the landing. A friend of mine who writes code for commercial rockets seemed to think that a lot about the stabilization methods could be learned with high quality, non-time-dilated footage of the landings. I would be a bit surprised if they did not have separate recordings of the landing for internal use to help diagnose failures. – OrangePeel52 Aug 18 '16 at 19:18
  • @blake6489 nails it! Your friend is right although I'm just doing it for fun myself, certainly a lot of people are examining things very closely. Of course maybe they were practicing "touch and go's", also here. – uhoh Aug 19 '16 at 00:47
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    Decent video of the approach and landing usually turns up a few days after the fact. If they were worried about information leaking out, they wouldn't publish those at all. – Hobbes Aug 19 '16 at 06:53
  • @Hobbes that's what I thought too. Maybe a school (flock?) of flying fish actually did fly between the rocket and ship after all, and it wasn't pretty? Has it shown up anywhere yet? – uhoh Aug 27 '16 at 08:08
  • @Hobbes: I hope it will be released some day for the SpaceX Demo-2 launch. – Eric Duminil Jun 17 '20 at 10:13
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Update 2: It doesn't!

Screenshots from GPS III Space Vehicle 05 Mission June 17, 2021, (video cued at T+ 07:52) which shows continuous video coverage all the way down from the 1st stage camera as well as continuous coverage from the camera on the boat ship (found in this @NASASpaceflight tweet):

Screenshot of SpaceX's "GPS III Space Vehicle 05 Mission" video, June 17, 2021 Screenshot of SpaceX's "GPS III Space Vehicle 05 Mission" video, June 17, 2021

Update1 : It doesn't always fail on every landing!

For example here's the SpaceX video from the ANASIS-II Mission.

Pardon the ugly GIF, I don't know how to make a better one...

GIF from ANASIS-II Mission

video cued at 23:19 or T+ 08:22

uhoh
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    This doesn’t address the op’s question. It’s more of a comment than an answer. It still frequently fails, which is clearly the concern of the op. – Paul Jul 20 '20 at 23:02
  • @Paul that's okay, future readers will be relieved to find out that the premise of the question is false. In this particular case I think it's sufficiently important to be included here. Less fodder for conspiracy theorists. – uhoh Jul 20 '20 at 23:06
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    @Paul "But for some reason every Falcon 9 landing's live feed from 'Of Course I Still Love You' cuts out just as it's coming into view. Why? Oh, why, does does it torture me so?" I really think that It doesn't always fail is the best answer to the question.The OP will be relieved to find out that they are no longer being "tortured" :-) – uhoh Jul 20 '20 at 23:11
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    The exception that proves the rule. – Schwern Jul 21 '20 at 04:34
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    Voted up because not every answer has to be strictly per the rules to be interesting and useful. This is a useful adjunct to the question and the existing answer. – Wayne Conrad Jul 21 '20 at 17:36
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    Here is a video feed that has no failure at all - https://m.youtube.com/watch?feature=youtu.be&v=KDK5TF2BOhQ – Joe Jobs Oct 28 '20 at 22:25
  • @Schwern I have struggled my whole life with that phrase :-) I will go for years believing that I understand what "the exception that proves the rule" means, then suddenly for years I don't understand what it means at all and it becomes self-contradictory. It's like a Rubin vase to me. Right now I'm in the second phase; how does the successful live broadcast prove the rule, and what exactly is the rule that it proves? – uhoh May 22 '21 at 00:29
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    @uhoh If you have to point out that one time it worked, then it near enough always fails. Working is the exceptional/usual case worthy of mentioning, failing is the rule. – Schwern May 22 '21 at 01:02
  • @Schwern I see, so a demonstration of a significant challenge of finding an exception or some other way of showing that it's a low probability will tell us not to expect it to happen very often in the future either for example. Finding a four leaf clover and getting excited about it and assigning it magical significance for example helps us to see it's a low frequency event. Got it, thanks! (Are four-leaf clovers mutations, developmental errors, or something more complicated?) – uhoh May 22 '21 at 01:12
  • @Schwern I've just added a second exception, does it very the proof of the rule or is it a stand-alone alternate proof? :-) – uhoh Jun 18 '21 at 04:38
  • @Schwern I've just added a second exception, does it* verify the proof* of the rule or does it qualify as a new, stand-alone alternate proof? :-) – uhoh Jun 18 '21 at 05:00
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    The question is about live feed. Not post landing edits. Which of these show a live feed of the landing? – Coomie Jun 21 '21 at 00:46
  • @Coomie that's a good question! I have assumed these are all in the live broadcast but I did not actually watch the latest one live so I can't vouch for it. I think that would be an excellent new question to ask separately; "Did the live coverage of GPS III Space Vehicle 05 Mission actually show the complete landing live or was it edited into Youtube later?" As an example of how to ask, you can review What is it that SpaceX is editing out of their videos after posting them on YouTube? Then we can revisit it here if necessary. – uhoh Jun 21 '21 at 01:07
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ANSWER: The feed is dropped because the conditions to maintain satellite lock are lost due to vibration created by the thrust of the engines as they slow the craft at the last stage of flight.

SIMPLE SOLUTION: SMALL unmanned boat that is towed behind the landing barge at a distance where vibration will not be a factor (300+ mts). This boat has stabilized GPS, all antennas, cameras (HD, etc) and media backup to capture and transmit in full time and glory the darn landing!

WHY OH WHY @SpaceX can you do such amazing things but you can't solve something so simple? very anticlimactic

Alex Pimienta
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