Comment by nerdsniper
14 hours ago
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)
The Chinese Yaogan-41 satellite is in geostationary orbit and might have a mirror in the 4m range.
https://www.csis.org/analysis/no-place-hide-look-chinas-geos...
> It would have a field of view roughly the size of Houston (50x50 miles)
Wait, what?
Like, this is a whole bunch of extremely unreliable numbers being stacked on top of each other to reach an unsupported conclusion, but how is a 50 square mile field of view supposed to find something in the middle of the pacific?
The satellite moves, so every orbit it captures a globe spanning strip that is 50 miles wide (here uncritically accepting the 50 miles figure).
And the carrier isn't going to be in the middle of the pacific, its going to want to launch strikes, so its going to be within (say 500 miles) of Chinese military targets, which does narrow down the size of the haystack somewhat.
But yes, this is a significant challenge. On the modern battlefield it is usually significantly harder to find something than to kill something after you have found it.
You only need to find the aircraft carrier once (say, when it docks) and then the satellite can remain pointed at it forever.