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Of course like many people I only know about military satellites from movies, so I wanted to get some information (perhaps get some myths debunked) by some experts:

  1. Can the military use a military satellite to spy on any place on Earth ? live?

  2. If a military satellite is used to spy on a rival country, can the latter detect it?

  3. I also was told that Google Maps sometimes blurs military bases, which made me wanna ask, is there some technology which can protect a military zone from prying satellites by shielding the area or something?

Thank you very much in advance!

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    $\begingroup$ Try to limit each question to one question, not 3 $\endgroup$
    – Topcode
    Commented Apr 29, 2022 at 1:26
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    $\begingroup$ "can the latter detect it ?" That depends a lot on which country you are asking about. $\endgroup$ Commented Apr 29, 2022 at 1:50
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    $\begingroup$ 1. yes, 2. yes, because the satellite itself is quite easy to detect. 3. camouflage, fake targets, or just hide underground when the satellite flies by. $\endgroup$ Commented Apr 29, 2022 at 3:47
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    $\begingroup$ AFIAK the standard approach in Area 51 was everything interesting was under cover whenever a Russian bird was above the horizon. At one point the local paper published some Russian spy sat photos--buildings and runways, not a bit of equipment to be seen. $\endgroup$ Commented Apr 29, 2022 at 4:19
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    $\begingroup$ 3. Yes, it's called a roof. $\endgroup$ Commented May 1, 2022 at 13:09

4 Answers 4

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Can the military use a military satellite to spy on any place on Earth?

Yes, but only in the absence of clouds. The highest resolution imagery is only available during the day. I strongly suspect they have infrared imagers as well for nighttime imagery, but those inherently have a lower resolution.

In principle, radar or even passive microwave could be used to look through clouds, but the resolution for passive microwave would be much poorer still.

Live?

No. The highest-resolution imagers are in low Earth orbit, so they would have to wait for a satellite to pass. They would also need to programme the imager on where to look, as it cannot look in all directions at the same time / quickly enough to cover everything during a pass (except at much lower resolution, but there are open data satellites such as weather satellites doing that already).

If a military satellite is used to spy on a rival country, can the latter detect it?

They can detect the satellite, but they wouldn't know if it was looking in their direction, nor if it was taking a photo.

If the spy sat uses radar, it would be easy to detect.

is there some technology which can protect a military zone from prying satellites by shielding the area or something

Yes. The technology is called digging. By hiding things underground, they cannot be seen from space or from the air. Other technologies may be camouflage or deception.

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    $\begingroup$ Yes i understand the point you made about having to wait for a satellite to pass the right place, and having them to program it for a specific spot, but at that point in time, wouldnt that allow them to view that location live for a while ? (at least until the satellite is out of range of view) $\endgroup$
    – RedZ
    Commented Apr 29, 2022 at 11:08
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    $\begingroup$ @RedZ Yes, in theory it could take multiple photos during an overpass, or even video, with some limitations. $\endgroup$
    – gerrit
    Commented Apr 29, 2022 at 12:00
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    $\begingroup$ @redZ. The orbital speed of LEO satellites means the time period it can view a single location from low earth orbit is very short, a couple of minutes at most. To get a rough idea find a time when you can spot the ISS spotthestation.nasa.gov/tracking_map.cfm and time how long it is visible to you (possible viewing) and within 30 degrees of vertical (optimal seeing for a camera). Also relevant that most of the places you might want 'live' feed of are not where your ground stations are so true live feed only easy to do over your own territory. $\endgroup$ Commented Apr 29, 2022 at 13:36
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    $\begingroup$ Regarding "In principle, radar or even passive microwave could be used to look through clouds, but the resolution would be much poorer still.", check out en.wikipedia.org/wiki/Synthetic-aperture_radar, which can provide very good resolution. Scott Manley gives a nice intro here: youtube.com/watch?v=u2bUKEi9It4. Obviously this is not passive, i.e., does not answer the original question. $\endgroup$
    – Simon
    Commented Apr 30, 2022 at 18:01
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    $\begingroup$ @Moo On the other hand, if I see a spy sat flying over, it's just in its regular orbit, and it's nothing special. If a spy plane flies over, then it's much more likely they're specifically targeting me. $\endgroup$
    – gerrit
    Commented May 2, 2022 at 9:06
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With respect to item 3, blurring photos - yes this happens.

It does not however happen through cloaking technology but rather more boringly by various organizations requesting it of either the company taking the original images or of Google etc who is hosting them. Random list.

One thing to be aware of here is that for most of the urban areas you see in google maps or similar services the images or not actually from satellite but an aircraft. Generally currently (2022) if you can see which way cars are facing it is an aircraft image, nor from space. Since these aircraft are normally operating with permission and under jurisdiction of the local government so much easier for them to mandate blurring or manipulation of the resulting images.

For google street view you can even request your own blurring. In all such measures it is worth remembering that blurring attracts attention which may be counter productive.

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  • $\begingroup$ You made some really good points, i didnt know that google maps uses aircraft images though, is there any other (free) service which provides satellite imagery though ? because the other day i tried to check a very remote location in an ocean but everything was low quality and low res so i guessed it might have been just computer generated and a not a real satellite feed, what do you think ? $\endgroup$
    – RedZ
    Commented Apr 29, 2022 at 19:18
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    $\begingroup$ @RedZ There's not much call for high-quality photos of the surface of the ocean, which is neither distinctive nor consistent, so while I'm sure the photos are genuine I'm equally sure that they are the lowest priority for getting better quality photos. $\endgroup$
    – dbmag9
    Commented Apr 29, 2022 at 20:57
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    $\begingroup$ @RedZ If you are viewing Google Maps, the image watermark contains the year the image was taken and the bottom of the screen tells you the company that provided it, which changes dynamically at different scales. $\endgroup$
    – dbmag9
    Commented Apr 29, 2022 at 21:01
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    $\begingroup$ Commercial satellite imagery can spot cars, tell which direction they're facing, and let you distinguish classes of vehicle (eg. compact car vs. pickup truck) with reasonable accuracy. Military satellite imagery can distinguish model of car with reasonable accuracy. To compare, a parking lot as seen by one of Maxar's satellites, and that same parking lot as seen by a simulated KH-11 satellite. $\endgroup$
    – Mark
    Commented Apr 29, 2022 at 23:11
  • $\begingroup$ That list in your first link seems to be largely nonsense, but it's easy to find such areas in France: go to Paris and look for the darker patches, somewhere inside them there'll be a blurred out building for pretty obvious reason (prison, military facilities) $\endgroup$
    – llama
    Commented May 2, 2022 at 2:23
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To answer question number 2.

There's actually a cottage industry among civilians to document and track spy satellites.

Here is a link with some more information about one such organization: Meet the Amateur Astronomers Hunting for Spy Satellites

You don't commonly hear about it in movies, but spy satellites tend to be quite large and to have large power requirements in order to support their advanced capabilities. This can result in them having expansive arrays of solar panels which reflect light at predictable angles. Satellites also often travel predictable paths in order to spy on certain regions.

Literally anyone with a sufficiently advanced telescope, or a good head for math, can scan the sky looking for satellites orbital paths, and for the reflections in their solar panels. It's become exponentially easier with the increased availability of AI that can comb hours of video footage looking for transiting objects or flashes from solar panels.

There was a big commotion around 2002-2004 (I don't remember exactly when) after astronomers in Japan noticed a previously undocumented satellite with solar panels the length of a football pitch, in exactly the right orbit to observe North Korea. The size of the solar array marked this out as being a particularly energy hungry spy satellite. Probably one with multiple passive and active system on board rather than just optics.

If civilians can do this, then the military of most nations can do it too.

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  • $\begingroup$ Very interesting information, im gonna research more based on what you mentioned, thank you very much! $\endgroup$
    – RedZ
    Commented May 1, 2022 at 18:11
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One surprising aspect of satellite imagery is that sometimes you can "see" things that are not there!

In regions of strong sunlight vehicles and aircraft on the ground leave cool shadows which remain for a time after the craft is moved. Thermal imaging can capture this. Also... engine runup and heat plume on ground can show which craft are on alert status, even at night.

During testing of aircraft and missiles for stealth capabilities they (or mockups) are mounted on a tall post and RF energy is directed at them. Our researchers had to make sure the craft were 'posted' for very short periods, day or night, so thermal shadows were minimized.

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  • $\begingroup$ That is very interesting, i did not know that, im trying to search more about this (thermal shadows) but couldnt find much, would you have any example image about it ? $\endgroup$
    – RedZ
    Commented Apr 29, 2022 at 19:24
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    $\begingroup$ I don't understand how this answers any of OPs questions. $\endgroup$
    – pipe
    Commented May 1, 2022 at 11:37
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    $\begingroup$ @pipe this information went to this point. Someone trying to hide stuff before a satellite comes over may fail if satellite uses sufficient IR imaging. This goes to the "undetected" by the hiders part of OP. $\endgroup$
    – BradV
    Commented May 1, 2022 at 14:34

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