Lincoln Experimental Satellite
Lincoln Experimental Satellite ( LES ) were a series of satellites funded by the US Air Force and manufactured by the Lincoln Laboratory at the Massachusetts Institute of Technology (MIT). Between 1965 and 1976, eight satellites were launched into space with six launches. The aim of the program was to test new devices and methods for military satellite communication.
The satellites were named LES 1 through LES 9. There were problems with some of the launches. LES 1 and LES 2 were to be deployed on an elliptical orbit of 2800 × 15000 km, but due to the failure of a booster they remained in a 2800 km circular orbit. LES 3 and LES 4 are expected to enter geostationary orbit , but also remained in a low circular orbit. All of these satellites gave usable results despite the wrong orbits. LES 5, 6, 8 and 9 reached geostationary orbit. The LES7 project was canceled when funding ran out.
Technologies tested on LES 1 through LES 4 included semiconductor X-band radios, low-power logic circuits, electronic despinning (using optics to locate the position of the earth and the sun relative to the rotating satellite at all times to determine, and then to switch the transmission via the best antenna in each case), and magnetic torque generators.
LES 3 was a very small satellite (16 kg), it was supposed to determine the extent of the multipath interference by reflection of 300 MHz radio waves from sufficiently flat parts of the earth.
LES 8 and LES 9 were satellites with a mass of around 450 kg, which were launched on March 15, 1976 (March 14, local time). They were originally supposed to be equipped with pulsed plasma engines, but were then given conventional engines. In contrast to what is customary for communications satellites, they were supplied with electricity from RTGs instead of solar cells. They communicated in the K-band from 36 to 38 GHz with each other ("cross-link") and with the earth on UHF. This cross-link technology, a novelty at the time, was subsequently used in NASA's TDRSS satellites . The original intention was to set up the network at a frequency in the 55-65 GHz range that would be absorbed by water so that earth-based receivers would not be disturbed by scattered signals ( radio windows ), but the technology was not like that at the time far. The satellites were operated in various positions until 1992 and have been slowly drifting away from the GEO orbit since then. The Lincoln Laboratory's next project was the construction of the EHF technology for the FLTSATCOM satellite communications system.
In the spring of 2013, an English amateur radio operator , Phil Williams ( amateur radio callsign G3YPQ) from North Cornwall , received signals from a tumbling satellite identified as LES 1. The 237 MHz transmitter is believed to operate by itself if the solar cells are exposed to the sun every 4 seconds.
Signals were received from LES 5 in March 2020.
Start list
All launches were from Cape Canaveral with Titan missiles .
| designation | Start (UTC) | NSSDC ID | Dimensions | status |
|---|---|---|---|---|
| LES 1 | February 11, 1965, 3:19 pm | 1965-008C | 31 kg | out of service in 1967, sporadic function |
| LES 2 | May 6, 1965, 3:00 p.m. | 1965-034B | 37 kg | out of order |
| LES 3 | December 21, 1965, 14:00 | 1965-108D | 16 kg | Re-entry April 6, 1968 |
| LES 4 | 1965-108B | 52 kg | Re-entry August 1, 1977 | |
| LES 5 | July 1, 1967, 1:15 pm | 1967-066E | 194 kg | out of service, sporadic function since March 2020 |
| LES 6 | 26 September 1968, 7:37 am | 1968-081D | 163 kg | out of service since January 1, 1976 |
| LES 8 | March 15, 1976, 1:25 am | 1976-023A | 454 kg | out of service since January 1, 1992 |
| LES 9 | 1976-023B | 454 kg | out of service since January 1, 1992 |
Web links
- LES in the Encyclopedia Astronautica (English)
Individual evidence
- ↑ LES in the Encyclopedia Astronautica, accessed on August 24, 2013 (English).
- ^ Thirty Years of Space Communications Research and Development at Lincoln Laboratory. Retrieved August 24, 2013 .
- ^ The Lincoln Experimental Satellite Program (LES-1,2,3,4): A Progress Report . In: American Institute of Aeronautics and Astronautics (Ed.): Proceedings of Communications Satellite Systems Conference May 2-4, 1966 . September.
- ^ Aerospace Corporation article . Archived from the original on February 7, 2012. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved September 26, 2013.
- ↑ Soundtrack on Youtube.
- ↑ Brad Smithfield: American satellite starts transmitting after being abandoned in 1967. October 23, 2015, accessed on August 6, 2019 .
- ↑ Frank Wunderlich-Pfeiffer: Zombie satellite from 1967 is broadcasting again. March 26, 2020, accessed March 26, 2020 .
- ↑ Space travel: Zombie satellite from 1967 broadcasts again - Golem.de. Retrieved on March 26, 2020 (German).
