LES 7 [Lincoln Laboratory]
The LES 7 (Lincoln Experimental Satellite 7) satellite was intended to have an all-solid-state, 100 MHz bandwidth, single-conversion, X-band repeater and a multibeam antenna. Although the program was cancelled before the satellite was built, a prototype antenna was built and tested. This antenna was a waveguide lens-type with a cluster of 19 feed horns and was capable of generating beam sizes as small as 3° and as large as Earth coverage.
MIT Lincoln Laboratory started a program to demonstrate, in orbit, a 19-beam (multiple-beam) antenna for reception at SHF. An Earth-coverage horn was to be used for the transmission. The 76 cm aperture of the receiving antenna yielded a nominal 3° resolution throughout the cone subtended by the Earth from geosynchronous-satellite altitude. The ground control terminal was to calculate the weights for the individual beams to approximate the desired antenna pattern and to transmit the weights to the satellite by telecommand.
The multiple-beam antenna, which was kept facing the Earth by the attitude control system, dominated the configuration of LES-7. Solar cell arrays followed the Sun to collect energy as LES-7 revolved in orbit. Work got under way to develop the satellite bus, which consisted of structure and housekeeping systems, power, propulsion, attitude control, thermal control, telemetry, and telecommand, in parallel with the development of the multiple-beam antenna and associated communications systems.
By early 1970, it became apparent that LES-7 was ahead of its time. Because there was not enough Pentagon support for the mission, the funding required for the satellite's development, launch, and evaluation in orbit was not available. With considerable regret, Lincoln Laboratory put aside the LES-7 flight program, but it developed the critical multiple-beam-antenna technology "on the bench" and at an antenna test range. The antenna technology developed for LES-7 was finally put to use with the DSCS-3 comsats in the early 80ies.
|Type / Application:
|MIT Lincoln Laboratory, USAF
|MIT Lincoln Laboratory
|Multibeam X-band payload
|2 deployable solar arrays, batteries