It seems US didn't coordinate Starshield's unusual spectrum use with other countries.
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US spy satellites built by SpaceX send signals in the “wrong direction”
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Thoughts as to whether these satellites would have enough receive gain to be using these bands for Doppler radar?
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The US once again using the diplomatic methods of: "Guess what? Screw you, that's what!"
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Strictly speaking, they're allowed to operate in a non-interfering manner (which they're apparently doing) in any band without consultation. It's only after a country complains that there's interference that we can just the US's diplomatic method.
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There was a time when I would have expected these to be reversed. Nowadays this does not surprise me in the least.
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Strictly speaking, they also don't give a fuck. Which is not surprising for a country where a certain person being caught cheating at golf becomes a national security issue.
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Given recent efforts to prematurely end the missions of earth observatory satellites, I can't help but wonder if interference with NASA and NOAA satellites was considered a beneficial side-effect by the powers-that-be in the US Government and SpaceX
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The author did a good job giving us the background and in exploring the implications of this. The two primary thoughts that struck me are that if an amateur home brewer observed this obvious activity, it is highly probable national states who explicitly seek out and monitor what clandestine spy satellites do are well aware of it.
Second, what the satellites are doing today is (also highly probable) to be of less importance than what they may be capable of doing under contingent circumstances.
Second, what the satellites are doing today is (also highly probable) to be of less importance than what they may be capable of doing under contingent circumstances.
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fellow human
Ars Praefectus
This was my thought too, or more generally: why would they do this? What are the benefits to them? I doubt stealth as you'd have to expect someone would notice at some point. Does it complicate jamming? Or simply an otherwise unused band so plenty of available bandwidth? Are the usual channels getting too crowded?
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Why not? Satellite-sourced SAR is a pretty well-understood mechanism , and the band they're using would seem to be good for medium-resolution imaging.
https://www.earthdata.nasa.gov/learn/earth-observation-data-basics/sar
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My first thought would be clandestine comms. A terminal operating outside the standard frequencies wouldn't necessarily be picked up by systems looking for Starlink traffic.
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@ Jon Brodkin
Outstanding article! Well researched, complete, organized, straightforward writing. Thanks so much.
Outstanding article! Well researched, complete, organized, straightforward writing. Thanks so much.
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Very well researched and informative article on an important subject to which I suspect most of us have little direct exposure.
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Great article, and I tip my hat to Tilley. It's clear he has a passion for this and is incredibly knowledgeable.
If a group of amateurs around the world can figure this out, you can bet nations certainly can too.
If a group of amateurs around the world can figure this out, you can bet nations certainly can too.
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"You see that screaming toddler over there? That's what you'll get if you don't send your child to our nice, safe kindergarten."
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Doppler radar would be specifically for moving targets if it's more focused toward the horizon than down-looking. Full global awareness of all moving craft seems like a military advantage.
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You skip putting the FCC Part 15 sticker on one measly constellation of intelligence satellites and everybody gets all up in arms, I tell ya
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I don't believe anyone thinks these are Starlink satellites doing Starlink business.
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But the majority of communications would still be in standard Starlink frequencies using standard protocols. The terminals and satellites being repurposed Starlink gear are going to operate more or less the same as Starlink - most of the time. Having some terminals that operate in random bands and mostly transmit straight up would make them harder to track than the standard off the shelf Starlink gear.
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Wait, so if I point my OTA TV antenna at a Starlink satellite, I can pick up NRO data on my TV from the comfort of my own home?! Gosh, that's so much easier than hitting the NRO analyst with a $5 wrench until he spills his secrets... it's so hard to find good $5 wrenches these days.
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Doing a bit of surmising here, but I don't think Doppler would be performant in all axes of movement, no matter the power/gain? I'd envision OpenCV-style motion detection analysis as a better situation solution.
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For these sats SpaceX removes the regular Starlink transmitters and installs transceivers from another company
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Doppler radar gives you the velocity along the transceiver direction. So a down-looking radar would see a velocity of zero for an aircraft at level flight. Sure, you can use image processing to give you velocities, but that takes processing.
Doppler radar gives you the velocity on the return signal directly. There's no more work than the heterodyning you have to do on a radar signal. If you're looking at the horizon, you're getting the component of velocity to/from the satellite. You can then filter for velocity ranges such that hypersonic vehicles would stick out like a sore thumb.
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"You know as well as we do that the right, as the world goes, is only in question between equals in power, while the strong do what they can and the weak suffer what they must"
(Thucydides, ~2500 years ago)
(Thucydides, ~2500 years ago)
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What you're describing is the mentality of "it's not wrong if we get away with it". If radio frequency spectrum was reserved for specific purposes, it should only be used for those purposes.
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Right there in TFA is a description that off-nominal uses are specifically allowed on a non-interfering basis. The "reservations" are for potentially interfering use cases.
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David Levinson: "It's like in chess: First, you strategically position your pieces and when the timing is right you strike. They're using this signal to synchronize their efforts and in 5 hours the countdown will be over."
Marty Gilbert: "And then what?"
David Levinson: "Checkmate."
Marty Gilbert: "And then what?"
David Levinson: "Checkmate."
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