alt Hacker NewsI don't believe parent is right, but satelites don't stay in one place unless they're on the equator, because otherwise they have to be moving. This means that you need many satelites to maintain coverage of a single spot.
I don't know how many military satelites China has, but I would have assumed it would be sufficient to cover the pacific sufficiently to find an aircraft carrier. (the obvious caveat here being clouds, which are fairly common over the ocean)
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nandomrumber • yesterday at 11:23 PM
> but satelites don't stay in one place
What?
> unless they're on the equator
What?
> because otherwise they have to be moving
What?
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The JWST has a 6.5 meter mirror. The largest (known) spy satellites have a mirror of ~3m diameter. At GEO (geostationary orbit) that would provide an imaging resolution of about 7 meters. An aircraft carrier is about 337x76 meters. So from geostationary altitudes, a satellite similar to a KH-11 would see an American aircraft carrier as a blob of about 48 "pixels". This is probably enough signal to track all aircraft carriers around the globe in real time. It would have a field of view roughly the size of Houston (50x50 miles) and would have enough electricity from solar panels to power reaction wheels to stay pointed at carrier groups indefinitely. (~15-year lifespan would be limited by xenon supply for ion thrusters that keeps the satellite in GEO orbit)