Could the Hubble Space Telescope see a human face from orbit?

At visible light wavelengths, the theoretical resolution of the HST is something like 0.04 arcseconds. At an altitude of 200 kilometers, this angular resolution translates to a linear scale of 4 centimeters or about 1 1/2 inch. This is enough to see your eye sockets, mouth and ears. Of course atmospheric turbulence would reduce this resolving power significantly so you would probably not be able to do more than identify the gross anatomical features of a human body. Evidently, the US Department of Defense is alleged to be able to read license plates from orbit, but the details of their instrument size, wavelength and orbit height are not known for comparison with HST. Clearly, by looking at infrared wavelengths, atmospheric turbulence is not as much of a problem, however for a given aperture size, the resolution is not as high as at optical wavelengths so there will be a trade-off between suppressing image turbulence and resolving power.


Copyright 1997 Dr. Sten Odenwald
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