[scanny]

That's not exactly how it works. The satellite operator will be taking paid orders to scan over specific areas of the earth, about 4km in width or so.

So you have to have a pretty good idea where the carrier is, and then you get an image delivered with some latency as the satellite will need to pass over a ground station that downlinks the data.

So it isn't free (although umbra has a CC BY 4.0 license for their data, much more permissive than other providers. Nor is it easy to search huge amounts of the ocean for the carrier.

What most entities probably do is tip and cue, which is use a sensor with coarser resolution to get an approximate location and then use a sensor with finer resolution to look closer.

[dist-epoch]

Sure, I was over simplifying it. China will already have a good idea where the carrier roughly is - the previous position.

And they will also have their own satellites.