Ships are giant hunks of metal and radio emitters. They light up on SAR satellites[0]. Sentinel-1 gets whole earth coverage and a revisit time of 1-3 days[1] with two active satellites. And that's the public stuff, if you can afford a fleet or even some extra fuel to steer them into interesting orbits you can get faster revisits.

[0] https://x.com/hwtnv/status/2031326840519041114 [1] https://sentiwiki.copernicus.eu/__attachments/1672913/Revisi...

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?

Satellites only have to track, not find.

Aircraft carriers sail from home ports and are frequently visible to all. The Charles de Gaulle was previously in Denmark for instance, then obviously everyone can also see you crossing the English Channel and Straight of Gibraltar.

So from there it is only a matter of keeping an eye on it for anyone with satellites. So obviously all the "big guys" know where the other guys' capital ships are.

You would only need to find it once, potentially at a port, and then you can follow it.

> it's actually very hard to find a ship, even as large as an aircraft carrier, in the ocean

I just ran some googled numbers over my envelope, and I get that the Mediterranean sea (great circle distance between Gibraltar and Beirut is 2300mi) is about 14000x larger than the bow-to-stern length (858') of the carrier.

That's... not that terribly difficult as an imaging problem. Just a very tractable number of well-resolved 12k phone camera images would be able to bullseye it.

Obviously there are technical problems to be solved, like how to get the phones into the stratosphere on a regular basis for coverage, and the annoyance of "clouds" blocking the view. So it's not a DIY project.

But it seems eminently doable to me. The barriers in place are definitely not that the "empty space is just too big". The globe is kinda small these days.

>Satellites have hard time taking pictures of every square mile of a sea to find any ship, yet alone the one you need.

That's why satellites use radars and scientific instrumentation magnetometers to find stuff like ships or even subs underwater.

This. You can search for years for a ship and never find it.