[cbsks]

I really don’t want to work for the defense industry, but I have to admit that they do have very fun problems to solve. You know there are people at NRO who are dedicated to ship tracking via satellite. I assume they can easily track ships without cloud cover, but how do they do it when it’s cloudy? Heat signatures? Synthetic Aperture Radar? Wake detection?

[jasonwatkinspdx]

ELINT and SAR.

For the first one, just look at wikipedia lists of government says that fly as little triangular constellations, like Yaogan 9A, 9B, 9C on this list: https://en.wikipedia.org/wiki/Yaogan

Those are ELINT birds that use multilateration to spot emitters globally.

SAR can spot wakes far, far, larger than ships using the same techniques as SAR measuring ground erosion, etc.

[mikkupikku]

I'd be mildly surprised if they not using SAR for this all the time, not only during cloud cover. The Soviet Union was using radar satellites (the RORSATs) to track carriers decades ago.

[mapt]

Neither SAR nor high resolution optical sensing are trivial at panopticon scale.

https://www.youtube.com/watch?v=-GTpBMPjjFc is a good overview of what's up there so far, and what's coming as they really try to scale the technology.

Bandwidth and processing are substantial bottlenecks with SAR; Only targeted and stationary applications have been broadly useful so far, and more focus has been put on planes than satellites for this. SAR is not as simple as taking a static image with a fixed resolution, your sensing window has got a target velocity and distance in mind and the antenna and processing needs to be tuned for that.

I would think that medium and high orbit optical tracking (daytime, cloudless sky) is probably used, because with video you can reasonably track subpixel targets if they're high contrast, without a lot of data transmission requirements.

[Sanzig]

> Bandwidth and processing are substantial bottlenecks with SAR; Only targeted and stationary applications have been broadly useful so far, and more focus has been put on planes than satellites for this.

I'm not sure why you assume this, this is factually incorrect. Satellite based SAR has been successfully used for civilian ship detection applications (traffic management, illegal fishing, smuggling detection, etc) for over three decades. I am sure its military use goes back much further.

> SAR is not as simple as taking a static image with a fixed resolution, your sensing window has got a target velocity and distance in mind and the antenna and processing needs to be tuned for that.

No? SAR satellites take thousands of SAR images of stationary scenes every day. It's true that object motion in the scene introduces artifacts, specifically displacement from true position - this is often called the "train off track" phenomenon, as a train moving at speed when viewed with SAR from the right angle will look like it's driving through the adjacent field rather than on the track. However, this isn't a significant problem, and can actually be useful in some situations (eg: looking at how far a ship is deflected from its wake to estimate its speed).

[convolvatron]

40 years ago the USN was working on using SAR with a elliptical kalmann filter to detect _submarine_ wakes. I assume things haven't digressed since then.

[dnautics]

> You know there are people at NRO who are dedicated to ship tracking via satellite.

I feel like there must be people at NRO whi are dedicated to sub tracking via satellite.

[drivebyhooting]

I wish defense paid better. The problems are infinitely more interesting than ads. And it’s not like social media is a saint anyway.

[jlarocco]

IME here in Colorado, a lot of them pay as well, or better, than run of the mill tech companies. I suspect the AI and "FAANG" companies may pay more, but I personally wouldn't work for any of those. In any case, I'd take $160k in Colorado over $240k in California any day.

And the problems are definitely a lot more interesting.

[drivebyhooting]

The problem is BigTech pays $800K or even $1M+.

[wahnfrieden]

Hmmm on the one hand murder, on the other hand ads

[tehjoker]

It would be fine if "defense" is what was meant, but they recently changed it back to a far more honest "department of war".

[drivebyhooting]

BigTech ought to renamed too. BigVice maybe?

[wolfi1]

when it's cloudy, heat signatures won't help, infrared is blocked by clouds