I wanted to ask about the system described in the following scenario...

A villain has built a system consisting of a telescope connected to a computer that runs some autonomous object recognition software. The villain's goal is to catalog all man-made satellites circling the earth, so that he can attack them from his secret base on the ground.

This is a stationary (but can be relocated, if needed) system, located in some desolate area sufficiently far from artificial light sources (but not necessarily on a particularly high altitude). It passively monitors all objects that pass over it and can use multiple steps to gain more information about an object after it recognizes it as a man-made satellite. The steps would be something like this:

  1. recognize the stars, planets, and the moon (so as to avoid cataloging these and for self-awareness of own location)
  2. recognize airplanes based on the lights on them (so as to avoid cataloging them)
  3. recognize objects that are not of type #1 or #2, i.e. something that is potentially a man-made satellite. These objects would be recognized by e.g. the object traversing (nearly)the same path in the sky at about the same time as once before.

When the system recognizes an object as a potential satellite, it would beam some radiation or laser on it so as to make it briefly more visible on some wavelength. The sensors on the system would then record how it looks like (in the particular wavelength) so as to catalog it more definitely.

The aim of the villain is to catalog the satellites of the country he considers his enemy. So this means that the system would have to be able to recognize satellites sufficiently well so as to differentiate what country they belong to. To some degree this would compare the found satellite to public data (such as is available for e.g. weather satellites).

On another hand I am not yet sure if it would be possible to differentiate country X military satellites from country Y military satellites, when no photos or other data may be available on the military satellites.

The questions I wanted to ask are:

  1. Would something like this be feasible?
  2. Approximately how large a telescope would the villain need?
  3. Would the system have to be located in specific part of the world to be able to recognize polar orbit satellites?
  4. Is there a way to make some far-away object more visible (in some particular wavelength) by e.g. shooting a laser at it?
  • $\begingroup$ Almost half of all satellites are in geostationary orbit. Unless they were above the system you describe, they wouldn't been detected. $\endgroup$ – Samuel Jan 2 '15 at 20:46

There is an awful lot of that data publicly available, NASA and the defense department are tracking over 500,000 different pieces of space junk orbiting the Earth. It is all cataloged as to size and most of the satellites are identified to at least who owns them, if not all of their capabilities.

I also found this web site https://www.space-track.org/auth/login which appears to try and collect and share most of the data you are looking for. So I would say you have a better chance of collecting the data from sources here on Earth than taking the time to try and map the skies.

Most satellites can detect EM emissions (that is how they communicate with the ground!) and Military Satellites have a much wider range of detection abilities. Unless the satellite is broadcasting it's information it would be very difficult for someone or something to identify who owns it by pictures, unless you have a large database of all known satellites.

  • $\begingroup$ exactly what I was going to say :) $\endgroup$ – dsollen Jan 1 '15 at 20:13

I second bowlturner's comment, there would be no point because we already know about every satellite out there Even most spy satellites are pretty well documented by the laymen.

Instead I wanted to add that no stationary system would be able to do much of interest. You could only see satellites that flow over that area. Since most satellites are geosynchronous, staying at roughly the same place their entire life, you would miss the vast majorities of satellites. Admittedly spy satellites, the most interesting ones to document, are not geosynchronous, but even those fly over a very specific ellipse, if your station does not happen to reside under the path of a satellite you won't see it. You could reposition, but you would have to reposition so often as to make the process very time consuming, and even then you could never be certain you say all the satellites.

There is nothing you need to do to make satellites more visible, a more precise telescope would be far more useful then trying to shoot a laser or to 'light up' the satellite. In truth since satellites are so close to earth they aren't that hard to view visible. The more interesting task though would be to record what electromagnetic signals may be coming out of those satellites. Unfortunately you could only record signals from the satellites that come close to your stationary object, and most EM emissions are very tightly focused beams, it would be hard to detect the emissions.


You could shoot lasers at sats... but that will reveal your secret base. And might get you targeted for return fire/investigation (if it's your own country's satellite). Most of the time they take getting hit with a laser passively, except for noting when/where it's coming from (and use side-viewing cameras on those locations).

AFAIK, there's no way to determine whose sat is whose, by just looking at them. Even if you could get a good view of them.

Also, military satellites can move or change orbits, and often have the fuel capacity to make use of that capability (not a lot, nor often - but they aren't just static).

http://www.spacetoday.org/Satellites/YugoWarSats.html http://www.nationaldefensemagazine.org/ARCHIVE/2004/DECEMBER/Pages/AirForceMulling5928.aspx


Geostationary sats are detectable, when they occlude stars. So I disagree with some of the other answers.


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