I do not want to start a debate about whether the government can spy on us from space or the invasion of privacy or USA PATRIOT act, thats for another board! Simply, when conspiracy theorists say that the government can watch us from space or we see satelite photos, how is it that these images are not blocked by clouds? Are they able to “see” through them? Do they wait until the area is clear? Or are they enhanced later on?
I had always assumed that they use IR, or some other part of the EM spectrum which isn’t hampered by clouds.
The optical sensors on the IMPROVED CRYSTAL are similar to the those of the KH-11. These electronic cameras provide real-time transmission of images to ground stations via Milstar relay satellites. The IMPROVED CRYSTAL sensors operate in visible and near infrared light, as well as thermal infrared to detect heat sources. These sensors probably incorporate low-light-level image intensifiers to provide night-time images. The KH-12’s have an infrared capability superior to that of the IMPROVED CRYSTAL, with the advantage in infrared primarily for camouflage detection, for looking at buried structures, for looking at differential thermal inertia in the target area, for trying to determine which factories are operating and which factories are not.
The IMPROVED CRYSTAL’s sophisticated electronics provides sharper images than the KH-11, comparable in quality to the best of the film return satellites, with a resolution approaching ten centimeters. A periscope-like rotating mirror reflects images onto the primary mirror, enabling the KH-12 to take pictures at very high angles of obliquity, imaging objects hundreds of kilometers away from its flight path.
Source: http://www.globalsecurity.org/space/systems/kh-12.htm
Despite its many advances, the KH-12 suffers the shortcoming common to all photographic intelligence satellite, the inability to see through clouds. With much of the Soviet Union and other areas of interest frequently covered with clouds, this has always posed a problem for intelligence collection. However, in the past, this problem was primarily one of directing the satellite’s coverage toward cloud-free areas, and awaiting improved visibility in cloudy regions. While this procedure may have been adequate for peace-time operations, it is clearly inadequate for war-time target acquisition.
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A space-based imaging radar can see through clouds, and utilization of synthetic aperture radar (SAR) techniques can potentially provide images with a resolution that approaches that of photographic reconnaissance satellites. A project to develop such a satellite was initiated in late 1976 by then-Director of Central Intelligence George Bush. This effort led to the successful test of the Indigo prototype imaging radar satellite in January 1982. Although the decision to proceed with an operational system was very controversial, development of the Lacrosse system was approved in 1983.
The distinguishing features of the design of the Lacrosse satellite include a very large radar antenna, and solar panels to provide electrical power for the radar transmitter. Reportedly, the solar arrays have a wingspan of almost 50 meters, which suggests that the power available to the radar could be in the range of 10 to 20 kilowatts, as much as ten times greater than that of any previously flown space-based radar.
It is difficult to assess the resolution that could be achieved by this radar in the absence of more detailed design information, but in principle the resolution might be expected to be better than one meter. While this is far short of the 10 centimeter resolution achievable with photographic means, it would certainly be adequate for the identification and tracking of major military units such as tanks or missile transporter vehicles. However, this high resolution would come at the expense of broad coverage, and would be achievable over an area of only a few tens of kilometers square. Thus the Lacrosse probably utilizes a variety of radar scanning modes, some providing high resolution images of small areas, and other modes offering lower resolution images of areas several hundred kilometers square. The processing of this data would require extensive computational power, requiring the transmission to ground stations of potentially several hundred mega-bits of data per second.
Source: http://www.globalsecurity.org/space/systems/lacrosse.htm