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LES 6 (Lincoln Experimental Satellite 6) was an experimental military UHF communications satellite.

In 1965, the Department of Defense established Tri-Service Program 591 (Tactical Satellite Communications) to enable the Army, Navy, and Air Force to evaluate the potential usefulness of satellite communications in the military UHF band. Lincoln Laboratory was chosen to provide the satellites essential to the test program. LES-5 was to be built and launched as soon as possible; LES-6 would incorporate improvements on LES-5 and would be launched a year later. The three military services would procure test terminals that would work with LES-5 and -6 and would arrange for their installation in ships and aircraft.

The LES-5 and LES-6 satellites had cylindrical shapes with equipment mounted on a platform near the center of the cylinder and normal to its axis. Both had multiple-element antennas mounted around the cylindrical surface. In addition to their communications equipment, the satellites carried solar cell degradation and radio frequency interference (RFI) experiments. LES-6 also had a prototype autonomous stationkeeping subsystem.

LES-6 was launched in September 1968 and was used in tests similar to those conducted with LES-5. The satellite operated satisfactorily. The communication subsystem continued in active use, although by 1975 the effective radiated power (EIRP) had decreased 8 dB from its initial value. It was turned off early in 1976 to avoid any frequency conflict with the Marisat 1 launched in February 1976.

Nation: USA
Type / Application: Experimental communication
Operator: MIT Lincoln Laboratory, USAF
Contractors: MIT Lincoln Laboratory
Equipment: ?
Configuration: ?
Propulsion: ?
Power: Solar cells, batteries
Mass: 163 kg
Orbit: 35771 km × 35847 km, 13.0
Satellite COSPAR Date LS Launch Vehicle Remarks
LES 6 (P67-2) 1968-081D 26.09.1968 CC LC-41 Titan-3C with OV2 5, OV5 2, OV5 4


Further LES missions:
Further STP missions: