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LES 1 (Lincoln Experimental Satellite 1) was a US military communications satellite launched from Cape Canaveral aboard a Titan 3A rocket.

The objective of the LES 1 was to test a solid state X-band transmitter in Earth orbit along with enabling technologies, including electronically despun antennas, stationkeeping and attitude control techniques, and testing of a mobile ground station, known as Lincoln Experimental Terminal 1. The LES satellite bus was a 26-sided polyhedron, with 18 square faces and 8 triangular faces. It had a diameter of 61 cm and a mass of 31 kg. The square faces were covered with 2,376 solar cells generating a minimum of 26 W in sunlight. The eight triangular faces held Earth and Sun sensors and eight semi-directional horn antennas. The Earth sensors were wired into a switching system that would turn on the antenna facing the Earth whenever the planet was detected.

A 200 milliwatt solid state X-band (7750 MHz) repeater transmitter used horn antennas to transmit modulated signals to ground stations. A UHF (237 MHz) 800 mW transmitter used a biphase modulator for the first time to transmit telemetry. An X-band (8350 MHz) receiver was used to receive ground signals. A timer was also part of the payload, designed to shut the mission down after two years. The satellite was spin stabilized at 180 rpm with magnetic torquing.

LES 1 launched on a Titan 3A (a modified two-stage Titan 2 ICBM with a third stage, or transtage) from Kennedy Space Center at 17:16:48 UT (12:16:48 EST) on 11 February 1965 into a 185 km parking orbit (although some sources list the launch time as 15:19:05 UT). This involved a 149 second first stage burn and a second stage burn of 206 seconds. It then raised its orbit with three transtage firings (of 290, 37, and 28 seconds) to reach a circular orbit with a altitude of 2800 km. The LES 1 satellite was then ejected by a series of springs and planned to raise the apogee to 18,500 km, but the solid fuel engine attached to the satellite failed to fire due to a wiring error, leaving LES 1 in its circular Earth orbit. From this unplanned orbit, LES 1 still managed to run useful communications tests, but because the rocket motor was still attached, the spacecraft soon began to tumble in a way to make the communications tests impossible. After two years, the timer shut the spacecraft down.

Oddly enough, in 2012 signals were detected from the satellite’s UHF transmitter. Apparently a short had developed in the system, and this allowed the solar cells to directly power the UHF transmitter whenever the satellite was in sunlight. The satellite was still transmitting as of 2022. Because of this, it is sometimes referred to as a "zombie satellite".

Alternate Names

  • 01002
  • Lincoln Experimental Satellite 1
  • LES1

Facts in Brief

Launch Date: 1965-02-11
Launch Vehicle: Titan III-A
Launch Site: Cape Canaveral, United States
Mass: 31 kg
Nominal Power: 26 W

Funding Agency

  • Department of Defense-Department of the Air Force (United States)


  • Communications
  • Engineering

Additional Information

Questions and comments about this spacecraft can be directed to: Coordinated Request and User Support Office

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