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We've all been there: you're discussing the recent launch of a rocket carrying a satellite to orbit, or what have you, and suddenly someone pops in and makes a comment like

Yeah, it's amazing and scary how powerful spy technology has become. They're probably watching us, as we speak!

Now, I know that such a statement is extremely unrealistic. There are simply not enough satellites up there to be constantly monitoring every square meter of the planet. But do such statements have some truth in them?

I realize that, as far as spy satellites are concerned, many things could be unknown because of their classified nature. But is technology advanced enough to monitor something relatively small from space? Like what someone looks like (or at least what the top of their head looks like, assuming the view is from the top), or the security code on a piece of paper, etc?

voithos
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    Is technology really advanced enough to monitor *something* on the planet from space? Sure! Do they monitor everyone and everything all the time? No way! There is no reason for it and no way to *process* all the information which is mostly unimportant. Who in the military cares about your conversation with your friends? – Martin Scharrer May 25 '11 at 19:06
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    Certainly satellites can monitor things on the planet from space, because they do. There are things they can't monitor. Could you be more specific in your question? What sorts of things are you asking about being monitored from space? – David Thornley May 25 '11 at 19:09
  • I heard once the story about that in the 80s or so the Russians send a photo to the Americans showing the US president sitting in his garden, reading a book which he hold in its hands. The story states that the resolution was good enough to read the text of the open pages ... – Martin Scharrer May 25 '11 at 19:12
  • @Martin: But what resolution can that _something_ be monitored at? Are we talking about something like being able to observe a target building, for example? Or something more like tracking an individual if necessary? Like that story- is something like that possible? – voithos May 25 '11 at 19:15
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    How advanced do "people" think they are? And on what scale? 25.7 kubriks per square gram? – Lennart Regebro May 25 '11 at 19:41
  • @voithos; Possible? Absolutely, we have telescopes more than capable of that level of magnification. Viable? That's a much harder question to answer. – Phoshi May 25 '11 at 20:24
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    @Martin the story is oft told but entirely false. I'd be a bit suprised if our best optics of today had that capability, let alone soviet technology of that era. Though in proper conspiratorial bent I'd have to "not put it past" the US spy industry to take that picture from a helicopter and claim it was from a Soviet satellite to get a better budget. ;) – The Real Bill May 26 '11 at 02:07
  • If the US military could monitor every conversation that happens in Afghanistan they probably would be better at catching insurgents. – Christian May 26 '11 at 21:03
  • @Christian - What's the difference between an average Taliban and a California mall teen girl? The latter is **guaranteed** to spend all her time on cell phone (source: any movie). The former is not. – user5341 May 27 '11 at 02:08
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    @Martin Scharrer: the basic physics of optics are well-known. To get a sub-centimeter optical resolution requires a satelite with a lens _at least_ 10 meters wide. In turn, such a satelite would have been spotted quite early by the Americans. The real question is how close the real satelites come to the physical limits. – MSalters May 27 '11 at 08:55
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    Even with a 10 meter object lens a satellite is not going to get Rayleigh criterion resolutions because the resolution will be limited by atmospheric turbulence. That's correctable at major land-bases astronomical observatories, but the spotter beams are pretty prominent. – dmckee --- ex-moderator kitten Jan 10 '14 at 00:25

4 Answers4

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Summary:

The satellites for which there is publically available info** are definitely incapable of resolutions supporting reading written text or even car license plates; nor distinguish facial features.

The best ones are supposed to be Keyhole-class KH-7 (2.5") followed by KH-11 (4-6").

Detailed quotes

First off, some results from http://hypertextbook.com/facts/2001/JeannelleLouis.shtml (Resolution of a Spy Satellite, The Physics Factbook™; Edited by Glenn Elert -- Written by his students)

  • Source: Massive New Top Secret Spy-Satellite Program to Cost up to $25 Billion. Los Angeles Times. 7 June 2001.

    Data: Approximately 6 inches on current satellites

  • Source: Satellites System Overview Articles. America Online: Path: Spy Satellites.

    Data: Type KH-11 Spy Satellites, 10 cm/4 inch resolution; KH-7 -1966 2" Resolution.

  • Source: Silber, Kenneth. Spy Satellites: Still a Few Steps Ahead. 21 September 1999.

    Data: According to an estimate by the private Federation of American Scientists (FAS), three satellites operated by the US National Reconnaissance Office (NRO) have resolutions as sharp as 10 centimeters (3.93 inches) -- in other words, the satellites can discern a softball-sized object from several hundred miles away."

From http://www.msnbc.msn.com/id/3077885/ns/technology_and_science-space/t/spy-satellites-enter-new-dimension/

Three are “visible light” satellites, the most recent of which resemble the Hubble Space Telescope and were built by the same contractor at the same Lockheed Martin facility in Sunnyvale, Calif. They are known in the spy trade as “Keyhole-class” satellites. And they have a resolution of 5 to 6 inches, meaning they can distinguish an object that small, but no smaller, on the ground.

Two other satellites are radar-imaging, built by Lockheed Martin in Watertown, Colo. Their resolution is about 3 feet.

While satellites cannot read license plates, they can tell if a car has one. While they cannot tell a mullah by the length of his beard, they can help analysts figure out how many people are chanting along with him at a street demonstration. And while they cannot hover over an area and provide real-time images, other “assets” such as unmanned aerial vehicles, also known as drones, can do that.

Please note that in addition to classified proprietary tech, the modern movenet is towards using commercial capabilities.

  • http://www.msnbc.msn.com/id/22046019/ns/technology_and_science-space/t/us-plans-next-gen-spy-satellite-program/

    The bulk of the article talks about cancellation of Boeing's Future Imagery Architecture (FIA) program. The rest covers what replaced it:

    U.S. commercial satellites now have better than two-foot resolution, meaning each pixel in a digital image spans 24 inches. In April, a satellite will be launched with 16-inch resolution. By 2011, that is expected to narrow to nearly 10 inches. Tighter resolutions let analysts see details that allow them to accurately identify missiles and other targets.

  • http://www.dodbuzz.com/2009/04/07/president-approves-new-satellite-system/

    As a GeoEye spokesman noted today, his company has already committed more than $30 million dollars to the next generation satellite, known as GeoEye 2, and ITT is already grinding its 1.1 meter mirror.

    Ground resolution for pictures taken from this satellite would be a remarkable 9.75 inches.

  • In addition, from the Washington Post article ("A LOOK AT Spy Satellites & Hollywood" By Dwayne A. Day); now saved at http://www.c4i.org/spysats.html

    (Dwayne Day is a space policy analyst and historian who lives in Northern Virginia. He is the editor of "Eye in the Sky" (Smithsonian Institution Press), a book about early spy satellites.)

    Even if a satellite had the right angle on the license plate, it wouldn't be able to make out the letters and numbers. The best resolution of an American spy satellite, achieved by an older series no longer in use, was reputed to be about 2 1/2 inches. This means that the smallest visible object would be the size of a baseball, not the thin letters and numbers on a license plate. And smoke, haze, smog or clouds would all reduce the quality of the resolution, as would the distance required to see the license plate from an angle. Memo to future filmmakers: License plates cannot be read from satellites.

    I presume he meant KH-7.

Community
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user5341
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  • I presume that these resolutions imply a stationary object? – MrHen May 26 '11 at 18:03
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    Note that the effective resolution might be increased with interferometry ( http://en.wikipedia.org/wiki/Astronomical_interferometer) – horatio May 26 '11 at 20:05
  • Does millimeter wave radar work from space? – duffbeer703 May 27 '11 at 01:58
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    @horatio - you'd need an array of satellites for that, which are capable of being 100% location-synchronized. I'm not certain that is feasible with current technology. The interferometer arrays you speak of are fixed earthside installations – user5341 May 27 '11 at 02:12
  • @duffbeer703 - not sure, but does anything on the surface emit the necessary wavelength radiation of sufficient strength? (or alternately, can a proper wavelentgth transmitter be put into orbit powerful enough to illuminate the target from orbit?). Also, millimeter wave radar may not be capable of distingushing writing/typesetting on a page, unlike visible wavelength instruments? Probably a good set of questions for Physics SE if somene bothers – user5341 May 27 '11 at 02:14
  • @horatio: To do interferometry you need to know the distance between sites to better than the signal wavelength and maintain a timing base better than the inverse signal frequency. Tough under the best conditions for the visible spectrum, and satellites in orbit are not the best conditions. //er..this comment assumed you meant between satellites. You can, of course, build an interferometer on a single paltform. – dmckee --- ex-moderator kitten May 28 '11 at 17:44
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    of course the conspiracy theorist (and in this case they will for once be correct) will claim that data on the actual spy sats is classified and not available. So we can probably assume that the actual state of the art is better than the KH-11. How much better, we can only guess at. But given Hubble as an upper limit for the lenses we can put in orbit, getting the resolution to read a book from orbit is way beyond us. – jwenting May 30 '11 at 06:11
  • "modern movenet": Typo? I can't be sure what it is meant to be. – Mark Hurd Mar 05 '13 at 02:45
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    If has lens resolution of 10cm, using [superresolution](http://en.wikipedia.org/wiki/Superresolution) techniques combining multiple frames you should be able to get much better resolution. I imagine, that with computers powerful enough, it would be even possible for live feed. And 10cm is for KH-11, which is almost 40 years old now. – vartec Jan 10 '14 at 12:44
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Trump's recent tweet of a photo of a high resolution satellite image of an Iranian launch failure has added some concrete data on US spy satellite capabilities.

Astronomers have determined it likely came from USA 224, a K-11 spy satellite. The resolution has been estimated to be at least 10 cm (about 4 inches), possibly better since the image is a photo of the satellite image. It's also possible the image has been digitally altered meaning the real resolution could be worse than 10 cm.

While the K-11 was first launched in 1976, USA 224 was launched in 2011 as probably a Block IV representing the best the US has to offer.

However, keep in mind the field of view of such satellites is narrow. While it might be able to take images at high resolution, it can only see a very, very, very small portion of the Earth at a time. Unless you've been specifically targeted, they are not "probably watching you, even as we speak" with satellites.

See Also

Schwern
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Just to add to what DVK said, the latest 'supposedly' advanced image satellite was launched in January 2011, dubbed USA-224.
http://en.wikipedia.org/wiki/USA-224

It seems to be based on the Lockheed KH-11 which was manufactured between 1976-1990. Though it is more likely to be based on a newer version ( sometimes called the KH-13) the KH-11 was the last numbered satellite before they started naming them randomly, so that the actual names are most likely still classified.

The KH-11, during the 80's , had a 2.4-meter mirror with a resolution of 6 inches. I don't think it too far fetched to say that image resolution technology and optics have come a long way since the 80's, though there are undoubtedly physical and other constraints, I would think if they are not currently able to reading license plates size lettering they are pretty damn close.

Also to note that image enhancement is getting better. http://www.iipl.fudan.edu.cn/~zhangjp/publications/ICME2009.pdf

dmckee --- ex-moderator kitten
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Wyck
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    The optics involved in this sort of satellite haven't changed much in the past four centuries: reflector telescope design (such as the [Cassegrain reflector](https://en.wikipedia.org/wiki/Cassegrain_reflector) used in KH-11) is pretty much mature, and manufacturing technology has permitted [diffraction-limited systems](https://en.wikipedia.org/wiki/Diffraction-limited_system) for at least a century. The optics advances of the past 40 years have been in refractive systems such as camera lenses. We know what it would take to read a license plate: a mirror at least 15 meters across. – Mark Sep 10 '19 at 01:42
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Eyes in the Sky: The Secret Rise of Gorgon Stare and How It Will Watch Us All Hardcover – June 18, 2019

Aerial surveillance of cities is now possible that tracks thousands of objects simultaneously and stores data so that one can go forward and backwards in time to trace such things as vehicle routes. You don't need satellites to have a drone over a city which can pretty much see everything at once. You won't have to necessarily read a license plate number as you can literally watch a car pull out of a driveway and trace it as it goes across town. Just another example that privacy is dead. You must assume that all movement is tracked as well as all digital data transactions over networks.

Sawyer W
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    [Welcome to Skeptics!](https://skeptics.meta.stackexchange.com/questions/1505/faq-welcome-to-new-users) Is that text from the book? If so, please use quote markup, and explain what it means - and tell us why the author believes it is true. Is it your text? In that case, tell us why you think it is true. Why do you think cities are being regularly surveilled by drones? – Oddthinking Sep 09 '19 at 18:16
  • yes, it is book title hardcover with publication date. It is probably the most current book on wide area persistent surveillance (WAPS). Here is a link to a commercial purveyor of same complete with brochures that give some specs. [https://www.baesystems.com/en-us/product/airborne-widearea-persistent-surveillance-system-awapss] It is hard to imagine this technology not being taken advantage of by various law enforcement and spy agencies. To my knowledge it has been used on Baltimore and by the FBI, border patrol and homeland security and I can only speculate about the NSA abuses. – Sawyer W Sep 11 '19 at 22:07
  • This isn't really an answer to the question, which is specifically about the capabilities of satellites. – GB supports the mod strike Sep 12 '19 at 02:46