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Power usage isn't necessarily huge. I worked on a SAR satellite a few years ago with a total RF power of <1kW. It's pulsed as well - you send an RF "chirp" at
by leoedin 6y ago
Power usage isn't necessarily huge. I worked on a SAR satellite a few years ago with a total RF power of <1kW.
It's pulsed as well - you send an RF "chirp" at a sub-1kHz pulse frequency. Depending on imaging mode the average power draw is probably in the 500W-1kW range.
That had a much larger resolution (6m rather than 50cm), but the resolution is a function of frequency and antenna design as much as power.
The SAR concept essentially creates an image by sending out a known RF chirp and then, for each pixel of the image, correlating the response with the expected signal from that pixel. That correlation means that even if the received signal is below the noise floor you can create an image.
- px43 6y agoGreat info, much appreciated. Still seems like kind of a lot of something that's supposed to live in space for years at a time. Presumably solar panels recharge a battery when it can, but continuous operations seem out of the question without some pretty large panels. Maybe I'm underestimating modern solar panels or something.
- madlag 6y agoEfficiency of solar panels on satellites is about 40%. That means ~ 700W/m2 if correctly oriented. That's quite a lot of power, even if you stay 50% of the time in night while orbiting Earth. So no need for huge panels usually. (Updated : more like 40%, not 50%)