Reconnaissance satellite

A Zenit 2 photo-reconnaissance satellite.

The tech

A reconnaissance satellite (AKA- a 'spy satellite', 'eaves dropping satellite' or 'spies in the skies system') is an orbiting Earth observation on to the planet's surface type space satellite or communications interception and/or dispersal satellite deployed for military or intelligence gathering and/or dispersal applications. The USA began drawing up the first plans for one in 1955 and the USSR started there own plans a year later.

Their roles

Some examples of reconnaissance satellite missions are:

• High resolution photography (IMINT).
• Measurement and Signature Intelligence (MASINT).
• Communications eavesdropping (SIGINT).
• Covert communications.
• Monitoring of Comprehensive Test Ban Treaty compliance (by 'National Technical Means').
• Enforcing ceasefires by watching the movement of aircraft, armour and ships.
• Detection of missile launches.

Their types

1. Missile [Launching] Early warning provides warning of an attack by detecting ballistic missile launches. 
2. Nuclear explosion detection identifies and characterizes nuclear explosions in space. 
3. Photo surveillance has images taken of Earth so theycan be a survey or close-look telephoto is the earliest known. Spectral imaging is now commonplace.
4. Electronic-reconnaissance and Signals intelligence intercepts stray radio waves. 
5. Radar imaging use space-based radars use synthetic aperture radar to take scrimmages at night or through heavy fog and cloud cover.

Earth observation satellites' transmission frequencies

General downlink frequencies

Satellite	Frequency	Band
Terra	8212.5 MHz	X band
Aqua	8160.0 MHz	X band
National Oceanic and Atmospheric Administration (NOAA) 17,18	1707.0 MHz	L band
European Remote Sensing Satellite (ERS-2) (High rate)	8140.0 MHz	X band
SPOT 4,5	8253.0MHz	X band
EROS A1	8150.0 and 8250.0 MHz	X band
Landsat 5, Landsat 7	8212.5 MHz	X band
China-Brazil Earth Resources Satellite program (CBERS) 2B	8103.0, 8321.0 and 8212.0 MHz	X band
Comisión Nacional de Actividades Espaciales (SAC-C)	8386.0 MHz	X band

Examples

• KH-1 "Corona", C
• Zenit 2
• SAMOS F2-1
• OPS 5346 Rhyolite
• Vela 5A and 5B (satellite)
• SAR-Lupe
• Helios

Also see

1. Spy plane
2. Lockheed U-2
3. Reconnaissance aircraft
4. Secret service radio stations
5. Electromagnetic spectrum

On-line links

1. http://en.wikipedia.org/wiki/Reconnaissance_satellite
2. http://en.wikipedia.org/wiki/Earth_observation_satellites_transmission_frequencies