# Lincoln Experimental Satellite 5

> former American communications satellite

**Wikidata**: [Q122973289](https://www.wikidata.org/wiki/Q122973289)  
**Source**: https://4ort.xyz/entity/lincoln-experimental-satellite-5

## Summary
Lincoln Experimental Satellite 5 (LES-5) was a former American communications satellite launched in 1967 as part of the Lincoln Experimental Satellite program. It was designed to demonstrate experimental technologies for military communications and operated in geostationary orbit until 1971.

## Key Facts
- Launched on July 1, 1967 at 13:15:01 UTC from Cape Canaveral Space Launch Complex 41
- Operated by the United States Air Force and MIT Lincoln Laboratory
- Weighed 194 kg at launch and 104 kg at service entry
- Dimensions: 163 cm tall, 122 cm in diameter
- Powered by solar cells producing 136 watts
- Launched aboard a Titan IIIC rocket (3C-14 mission)
- Retired from service in May 1971
- Remarkably, it was rediscovered in 2020 by amateur radio operators still transmitting telemetry

## FAQs
### Q: What was the purpose of Lincoln Experimental Satellite 5?
A: LES-5 was a technology demonstration spacecraft designed to test experimental communications technologies for military applications, specifically for the United States Air Force.

### Q: When was LES-5 launched and how long did it operate?
A: LES-5 was launched on July 1, 1967, and operated in geostationary orbit until May 1971, when it was retired from service.

### Q: What happened to LES-5 after it was retired?
A: After retirement in 1971, LES-5 continued to orbit Earth. In 2020, amateur radio operators discovered it was still transmitting telemetry signals, making it one of the oldest operational satellites still in orbit.

## Why It Matters
Lincoln Experimental Satellite 5 represents a significant milestone in the development of military communications technology. As part of the Lincoln Experimental Satellite program, it helped advance the understanding of satellite-based communications systems that would become critical for national defense. The satellite demonstrated the viability of geostationary communications satellites for military applications, paving the way for more sophisticated systems that followed. Its rediscovery in 2020 also highlights the remarkable longevity of space hardware and the ongoing interest of amateur radio operators in tracking and monitoring satellites. The fact that LES-5 continued transmitting for over 50 years after launch demonstrates the durability of space technology from this era and provides valuable data for studying long-term satellite behavior in orbit.

## Notable For
- One of the earliest successful geostationary communications satellites for military use
- Demonstrated experimental technologies that influenced later military satellite communications
- Remarkably durable design that allowed it to transmit for over five decades
- Part of the pioneering Lincoln Experimental Satellite program that advanced space communications
- Rediscovered in 2020 as one of the oldest operational satellites still transmitting telemetry

## Body
### Development and Design
LES-5 was developed by MIT Lincoln Laboratory as part of a series of experimental satellites built for the United States Air Force. The satellite was designed to test and demonstrate new communications technologies in the challenging environment of space. Its compact design, measuring 163 cm in height and 122 cm in diameter, incorporated solar cells for power generation, producing 136 watts of electrical power.

### Launch and Operations
The satellite launched on July 1, 1967, aboard a Titan IIIC rocket as mission 3C-14 from Cape Canaveral Space Launch Complex 41. After reaching geostationary orbit, LES-5 operated as a communications satellite for the United States Air Force, demonstrating the practical applications of satellite-based communications for military purposes. The satellite weighed 194 kg at launch but reduced to 104 kg at service entry as propellant was consumed.

### Technical Specifications
LES-5 featured a robust design that allowed it to function for decades beyond its intended service life. The satellite's solar cell array provided reliable power generation, and its communications systems were designed to operate in the harsh radiation environment of geostationary orbit. The satellite's COSPAR ID is 1967-066E, and it is cataloged in the NSSDCA database with the same identifier.

### Legacy and Rediscovery
After being retired from service in May 1971, LES-5 continued to orbit Earth in geostationary position. In a remarkable turn of events, amateur radio operators discovered in March 2020 that the satellite was still transmitting telemetry signals. This discovery made LES-5 one of the oldest operational satellites still in orbit and demonstrated the exceptional durability of its design. The satellite's continued operation more than 50 years after launch provides valuable insights into the long-term behavior of space hardware and the persistence of radio signals in space.

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## References

1. [Source](https://space.skyrocket.de/doc_sdat/les-5.htm)
2. Jonathan's Space Report
3. [Source](http://aerospace.wpengine.netdna-cdn.com/wp-content/uploads/2012/03/bk_comm-sats_ch1.pdf)
4. [Source](https://www.npr.org/2020/04/24/843493304/long-lost-u-s-military-satellite-found-by-amateur-radio-operator)
5. [Source](https://www.popularmechanics.com/space/satellites/a32293223/les-5-satellite/)