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> As I understand it the newspaper story is bull Could you clarify what you mean by this? And yeah, I should have been more clear in my original question; I w

> As I understand it the newspaper story is bull Could you clarify what you mean by this? And yeah, I should have been more clear in my original question; I was lumping mathematical advances under "technology".

marssaxman 13y ago
The resolution of a lens at a given wavelength is determined by its diameter (Rayleigh function). We know how big the launch vehicles are, so we can estimate the largest size a spy satellite's mirror could be, and we can use that to compute the maximum resolution a satellite could have; it turns out to be something around 5-10 cm. In order to resolve a newspaper from near-earth orbit, you'd need a lens bigger than the ISS, and if such an object existed it would be one of the brightest objects in the sky.
- ErsatzVerkehr 13y ago
  Would it be possible to improve the resolution of optical imagery using a synthetic aperture?
  - marssaxman 13y ago
    Beyond my knowledge, sorry.
    - gregholmberg 13y ago
      Yes, much finer optical resolution is possible if you use multiple instruments separated by a controlled interval. In radioastronomy, there are arrays of dishes that use this technique. There are good pictures in the Wikipedia article. [0] One military implementation was a connected three-satellite constellation, built by the US Navy for scanning the surface of the world's oceans. [1] But those tools work in (relatively) long wavelengths. I have never heard of free-flight multi-aperature interferometry that works in optical or near-optical wavelengths. . [0] "Very-long-baseline interferometry" https://en.wikipedia.org/wiki/Very-long-baseline_interferometry https://en.wikipedia.org/wiki/Very-long-baseline_interferome... [0] "How VLBI Works" https://en.wikipedia.org/wiki/Very-long-baseline_interferometry#How_VLBI_Works https://en.wikipedia.org/wiki/Very-long-baseline_interferome... [1] "White Cloud | PARCAE | NOSS" https://en.wikipedia.org/wiki/Naval_Ocean_Surveillance_System https://en.wikipedia.org/wiki/Naval_Ocean_Surveillance_Syste...
  - jlgreco 13y ago
    Yes, aperture synthesis is possible with optical wavelengths. I don't know how practical it would be to actually use with spy satellites, or how much of an improvement they could see with it. Keep in mind that there are a lot of people that track satellites, even spy satellites, as a hobby. I haven't heard of anyone discovering two or more satellites orbiting in the sort of tight formation you would expect would be required for this.

marssaxman 13y ago

The resolution of a lens at a given wavelength is determined by its diameter (Rayleigh function). We know how big the launch vehicles are, so we can estimate the largest size a spy satellite's mirror could be, and we can use that to compute the maximum resolution a satellite could have; it turns out to be something around 5-10 cm. In order to resolve a newspaper from near-earth orbit, you'd need a lens bigger than the ISS, and if such an object existed it would be one of the brightest objects in the sky.

ErsatzVerkehr 13y ago
Would it be possible to improve the resolution of optical imagery using a synthetic aperture?
- marssaxman 13y ago
  Beyond my knowledge, sorry.
  - gregholmberg 13y ago
    Yes, much finer optical resolution is possible if you use multiple instruments separated by a controlled interval. In radioastronomy, there are arrays of dishes that use this technique. There are good pictures in the Wikipedia article. [0] One military implementation was a connected three-satellite constellation, built by the US Navy for scanning the surface of the world's oceans. [1] But those tools work in (relatively) long wavelengths. I have never heard of free-flight multi-aperature interferometry that works in optical or near-optical wavelengths. . [0] "Very-long-baseline interferometry" https://en.wikipedia.org/wiki/Very-long-baseline_interferometry https://en.wikipedia.org/wiki/Very-long-baseline_interferome... [0] "How VLBI Works" https://en.wikipedia.org/wiki/Very-long-baseline_interferometry#How_VLBI_Works https://en.wikipedia.org/wiki/Very-long-baseline_interferome... [1] "White Cloud | PARCAE | NOSS" https://en.wikipedia.org/wiki/Naval_Ocean_Surveillance_System https://en.wikipedia.org/wiki/Naval_Ocean_Surveillance_Syste...
- jlgreco 13y ago
  Yes, aperture synthesis is possible with optical wavelengths. I don't know how practical it would be to actually use with spy satellites, or how much of an improvement they could see with it. Keep in mind that there are a lot of people that track satellites, even spy satellites, as a hobby. I haven't heard of anyone discovering two or more satellites orbiting in the sort of tight formation you would expect would be required for this.