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?

  • $\begingroup$ A simple idea is to have a manned aircraft, or drone, sending the video to a ship nearby which has the satallite antenna on it. If there is a safe zone that reaches too far, the relay ship could be temporarily abandoned during touch down. Or an easier idea, maybe Of Course I Still Love You could send a non directional signal to a second boat just outside of the safe zone that carries the satellite dish. $\endgroup$ – Johnny Robinson Aug 18 '16 at 22:13
  • $\begingroup$ The F9Heavy central core "landing" (roadster launch) indicates why you would want to have a large safe-zone around the landing site. The cost of laying out a long floating cable, to another ship, then evacuating to yet another ship is maybe not worth the cost of a few seconds live footage - the footage is still recorded and the link comes back up shortly afterwards. $\endgroup$ – Baldrickk Feb 15 '18 at 14:55

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.

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    $\begingroup$ 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. $\endgroup$ – uhoh Aug 18 '16 at 5:56
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    $\begingroup$ @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. $\endgroup$ – Hobbes Aug 18 '16 at 7:55
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    $\begingroup$ @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. $\endgroup$ – Hobbes Aug 18 '16 at 7:56
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    $\begingroup$ 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. $\endgroup$ – OrangePeel52 Aug 18 '16 at 19:18
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    $\begingroup$ 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. $\endgroup$ – Hobbes Aug 19 '16 at 6:53

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


protected by Community Aug 8 '18 at 11:54

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