Jim Lux wrote: > At 06:32 AM 10/30/2006, Jim Lux wrote: >> At 12:45 AM 10/30/2006, Jakob Oestergaard wrote: >>> On Fri, Oct 20, 2006 at 04:21:31PM -0400, Robert G. Brown wrote: >>> ... >>> ... >>> > geosync on Earth, and if the military and weather programs have >>> given us >>> > nothing else, they've given us simply gangbusters orbital cameras. I >>> > mean who on this list hasn't gone on Google Earth yet? Through >>> EARTH's >>> > atmosphere and from EARTH orbit you can see my house here: >>> > >>> > 35^\circ 59' 17.10"N >>> > 78^\circ 58' 50.22"W >>> > >>> > At 512 feet you can clearly make out my Ford Excursion in the >>> driveway, >>> > see the row of cypruses along the back, see the white table on my back >>> > deck that is about 4' across, see an azalea bush out front (next to >>> the >>> > sidewalk) that is about 1.5' across. And this isn't the world's best >>> > camera or as high resolution as they could manage, even through >>> Earth's >>> > soupy atmosphere. >>> >>> Mmm... Except... The high res images are from a plane because you can't >>> really make out the fine details from a satellite through the earth's >>> atmosphere. > > It's true that most of the Google Earth images are aerial photos, but > I would imagine that one can get 10s of centimeter resolution from orbit > on Earth (assuming that clouds aren't in the way). An old surveillance > satellite (Corona) was doing better than 2 meter resolution in the 1970s.
Absolutely. Assume modern recon sats use a primary mirror similar in size to the Hubble primary (both made by Perkin-Elmer). Calculating the Rayleigh limit for an Improved Crystal satellite such as that launched with USA 186 (Apogee 1050km, Perogee 264km) gives a max resolution of 7.9cm at 600nm and min resolution 31.5cm at 600nm. Space Imaging typically quotes max res. of 1m with IKONOS. DigitalGlobe says 61cm in B&W with their satellites. I would suspect that methods for dealing with atmospheric degradation is the secret sauce in the NROs architecture, especially WRT real-time applications of IMGINT. -- Geoffrey D. Jacobs Go to the Chinese Restaurant, Order the Special _______________________________________________ Beowulf mailing list, [email protected] To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
