Military Spy Satellite

First of all, Spy Satellites is referred as military reconnaissance and surveillance satellites. Though these Spy Satellites operate in many parts of the electromagnetic spectrum, these military satellites provide intelligence of the enemy capabilities and their activities.

The first generation of spy satellites was Corona and Zenit. During the development of these satellites, it was officially requested and demanded by the United States Air Force dated March the 16^th, 1955.

The main purpose of the demands was to have a continuous surveillance of some areas of some potential enemies in determining the weapons-making capabilities. Between the year of 1957 and 1999, about 4000 satellites were launched into space without fail, and about 50 percent of these satellites, will be used for specifically military purposes. Other functions of the satellites are such positioning and navigation, analyzing and recording information about the terrain (remote sensing), geodesy, research and meteorology. Though other satellites such as civil commercial satellites were used at times for several military tasks, which includes command assistance and military logistics support; a satellite with purely military uses, have certain capabilities and multiple systems that is specify for military uses that differs from the commercial ones.

NAVSTAR GPS (Navigation Signal Timing and Ranging Global Positioning System), is one of the best example of a military satellite that is operated by the US Air Force. It was first launched in 1978, but for the system to be fully operational was declared in April, 1995. The NAVSTAR satellites are arranged in six planes, each orbit back to the same spot on earth in a 12 hour, 20,000km high orbit. Each of the satellite will broadcast out two L-band radio signals containing ranging codes, ephemeris parameters, and Coordinate Universal Time (UTC) synchronization information. Other military users such as civilian users are able to receive, decode, and process the signals that receive from the NAVSTAR-GPS, to gain 2D or 3D position, velocity and time information. Civilian receivers then to lack of ability to read coded portions of the satellite transmissions.

References:

David Darling - The Internet Encyclopedia of Science: Satellites & Space Probes, “NAVSTAR (Navigation Satellite Time and Ranging)” [Online] Available from http://www.daviddarling.info/encyclopedia/N/NAVSTAR.html [Accessed on 17th January 2011]

Charlie Leonard (1999) – Introduction to NAVSTAR GPS. [Online] Available from http://people.csail.mit.edu/rudolph/Teaching/Lectures07/L8-navstar-2.pdf [Accessed on 17th January 2011]

Nicholas M. Short – RST, Introduction Technical and Historical Perspectives or Remote Sensing “Military Intelligence Satellites”. [Online] Available from http://rst.gsfc.nasa.gov/Intro/Part2_26e.html [Accessed on 17th January 2011]

Jason C. Chacis (2010) – BrightHub, Space Technology “Military Satellites: Meaning and Purpose”. [Online] Available from http://www.brighthub.com/science/space/articles/26768.aspx [Accessed on 17th January 2011]