3 ms·

Disclaimer: My opinion. I am fairly sure, no one is taking pictures of the whole earth, in 20 minutes intervals in a sufficiently high resolution to pick out a

Disclaimer: My opinion. I am fairly sure, no one is taking pictures of the whole earth, in 20 minutes intervals in a sufficiently high resolution to pick out an airplane. Specially one, flying over water. For reference, ISS at its height ~400km, can see roughly 3% of the Earth's surface. This is without any kind of lens. If someone has any kind of evidence, showing it otherwise, it would be great to see.

FractalParadigm 6y ago
Theoretically, if Starlink satellites had cameras of that sort of caliber on-board, pointed down with wide enough lenses, they could capture the entire planet continuously and feed that data back down at close to real-time.
deleted 6y ago
[deleted]
vaguesortof 6y ago
In a few years Blacksky should have a capability close to what you're describing
parsimo2010 6y ago
Nobody is going to offer evidence otherwise. Here’s a quick estimate for what you’re talking about: the Earth is about 500 trillion square meters of surface area. An image where each pixel was a meter would be a 500 TP (terapixel) image. Even with impressive compression the downlink requirements alone are insane, even ignoring all the other issues that would have to be worked out. Edit: just for fun, I estimated the file size- likely between 50 and 100 terabytes per image. We’ll get there one day, but no satellite constellation is downlinking that much data just yet. https://toolstud.io/photo/megapixel.php?compare=video&calculate=compressed&width=20000000&height=25000000 https://toolstud.io/photo/megapixel.php?compare=video&calcul... The bottom line is that nobody is imaging the entire surface of the Earth at any useful resolution daily (aside from low resolution meteorological satellites, but they can’t find a plane). If you want to track a plane you have to start with other means to point a camera and take an image. There is a huge difference between a company that has enough satellites in orbit to be able to take an image of any requested area within 20 minutes, and a company that can take an image of all areas on Earth every 20 minutes. MH370 is very unlikely to be captured in an image by coincidence. If there is imagery of it during its last flight then it would be because someone knew in advance that something was going to happen (it seems unlikely that anyone would have known).
- rexreed 6y ago
  Who would take a picture of the entire earth as a single image at one time? Take that 500 Trillion Square Meters and divide it up by 1000 satellites (or whatever Starlink plans) and take images sequentially rather than all at once and it becomes rapidly much more manageable. You don't need a single mult-terapixel image. You just need lots of much smaller images covering more territory on a continuous basis. if you wanted pictures of the entire earth every 20 minutes, you'd need to figure out how many satellites would give you that coverage, the amount of resolution per image, and the bandwidth requirements transportation of those images in parallel. Realistically, to get whole-earth coverage every 20 minutes would require a very large constellation of satellites. It's much more reasonable to get some less-than-100% coverage of the earth on a less-than-every-20-minute schedule and scale up from there.
  - parsimo2010 6y ago
    The motivating discussion here was that a commenter up a few levels was talking about how there just had to be some images of MH370 even if nobody tasked a satellite to track that specific plane. The suggestion was that we had constellations in operation that took images of everywhere on Earth every 20 minutes, so the plane had to show up somewhere, we just needed to sift through the images. But the commenter above me pointed out that was a silly assumption and I supported that comment. It doesn't matter whether you have a few satellites with a wide field of view taking a few huge images, or a bunch of satellites taking a bunch of smaller images- the grand total is about 500 terapixels to image the Earth at a 1 meter resolution. That's a ton of data to downlink regardless of how you collect it. Assuming great compression, this hypothetical system would have to be downlinking 50 TB every 20 minutes- that's over 300 gigabit/s. That's more than the downlink of a $600 million satellite (https://en.wikipedia.org/wiki/ViaSat-2 https://en.wikipedia.org/wiki/ViaSat-2) just to get some crappy resolution images. No civilian company is collecting anywhere near the entire surface of the earth at resolutions good enough to spot a plane. You are not tracking down MH370 if your approach is to find it in old satellite imagery. No satellite is taking pictures of vast swaths of empty ocean because there was no profit in it.

FractalParadigm 6y ago

Theoretically, if Starlink satellites had cameras of that sort of caliber on-board, pointed down with wide enough lenses, they could capture the entire planet continuously and feed that data back down at close to real-time.

deleted 6y ago

[deleted]

vaguesortof 6y ago

In a few years Blacksky should have a capability close to what you're describing

parsimo2010 6y ago

Nobody is going to offer evidence otherwise. Here’s a quick estimate for what you’re talking about: the Earth is about 500 trillion square meters of surface area. An image where each pixel was a meter would be a 500 TP (terapixel) image. Even with impressive compression the downlink requirements alone are insane, even ignoring all the other issues that would have to be worked out. Edit: just for fun, I estimated the file size- likely between 50 and 100 terabytes per image. We’ll get there one day, but no satellite constellation is downlinking that much data just yet. https://toolstud.io/photo/megapixel.php?compare=video&calculate=compressed&width=20000000&height=25000000 https://toolstud.io/photo/megapixel.php?compare=video&calcul... The bottom line is that nobody is imaging the entire surface of the Earth at any useful resolution daily (aside from low resolution meteorological satellites, but they can’t find a plane). If you want to track a plane you have to start with other means to point a camera and take an image. There is a huge difference between a company that has enough satellites in orbit to be able to take an image of any requested area within 20 minutes, and a company that can take an image of all areas on Earth every 20 minutes. MH370 is very unlikely to be captured in an image by coincidence. If there is imagery of it during its last flight then it would be because someone knew in advance that something was going to happen (it seems unlikely that anyone would have known).

rexreed 6y ago
Who would take a picture of the entire earth as a single image at one time? Take that 500 Trillion Square Meters and divide it up by 1000 satellites (or whatever Starlink plans) and take images sequentially rather than all at once and it becomes rapidly much more manageable. You don't need a single mult-terapixel image. You just need lots of much smaller images covering more territory on a continuous basis. if you wanted pictures of the entire earth every 20 minutes, you'd need to figure out how many satellites would give you that coverage, the amount of resolution per image, and the bandwidth requirements transportation of those images in parallel. Realistically, to get whole-earth coverage every 20 minutes would require a very large constellation of satellites. It's much more reasonable to get some less-than-100% coverage of the earth on a less-than-every-20-minute schedule and scale up from there.
- parsimo2010 6y ago
  The motivating discussion here was that a commenter up a few levels was talking about how there just had to be some images of MH370 even if nobody tasked a satellite to track that specific plane. The suggestion was that we had constellations in operation that took images of everywhere on Earth every 20 minutes, so the plane had to show up somewhere, we just needed to sift through the images. But the commenter above me pointed out that was a silly assumption and I supported that comment. It doesn't matter whether you have a few satellites with a wide field of view taking a few huge images, or a bunch of satellites taking a bunch of smaller images- the grand total is about 500 terapixels to image the Earth at a 1 meter resolution. That's a ton of data to downlink regardless of how you collect it. Assuming great compression, this hypothetical system would have to be downlinking 50 TB every 20 minutes- that's over 300 gigabit/s. That's more than the downlink of a $600 million satellite (https://en.wikipedia.org/wiki/ViaSat-2 https://en.wikipedia.org/wiki/ViaSat-2) just to get some crappy resolution images. No civilian company is collecting anywhere near the entire surface of the earth at resolutions good enough to spot a plane. You are not tracking down MH370 if your approach is to find it in old satellite imagery. No satellite is taking pictures of vast swaths of empty ocean because there was no profit in it.