LES - Credit: NASA. 29,819 bytes. 279 x 311 pixels.

The LES (Lincoln Experimental Satellite) spacecraft were designed and built by the MIT Lincoln Laboratory in Lexington, Massachusetts, as part of the Laboratory's Air Force-sponsored program in space communications, to test realistically, in orbit, new devices and techniques developed for possible use in satellite communication systems. LES-5, launched July 1, 1967, was designed primarily to aid in the development of a tactical satellite communication (TACSATCOM) system for the Department of Defense. It was used for the first communications by satellite among Army, Navy, and Air Force units, including aircraft in flight, submarines and surface vessels, and a variety of ground terminals. LES-5 was the first communication satellite to operate entirely in the government-allocated UHF-band (225-400 MHz), and it carried the first UHF-band satellite antenna system that generated circularly polarised radio signals to minimise fading and communication dropouts and to allow a surface terminal to use a very small, simple antenna such as a whip or stub monopole. LES-3, a UHF-band radio signal generator launched in December 1965, helped to establish design criteria for LES-5. LES-1, -2, and -4, also launched in 1965, operated at X-band (approximately 8,000 Mhz), and successfully tested a number of important new devices and techniques, including the first all-solid-state communication satellite transmitters and the first "electronically despun" (earth-sensing and antenna-beam-switching) system to increase the effective radiated power from the satellite.

Lincoln Experimental Satellite; communications experiments. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

Experimental commsat. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

Radio signal source for commsat tests. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

Experimental commsat. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

Experimental commsat. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

Spacecraft engaged in practical applications and uses of space technology such as weather or communication. Also tested pulsed plasma engines.

• 2 - McDowell, Jonathan, The United Nations Registry of Space Objects, Harvard University, 1997. HTML when accessed: http://hea-www.harvard.edu/QEDT/jcm/space/un/un.html
• 6 - JPL Mission and Spacecraft Library, Jet Propulsion Laboratory, 1997. HTML when accessed: http://msl.jpl.nasa.gov/home.html
• 405 - Aerospace Yearbook, 1966, .