LES-1, the enigma of the 'zombie' satellite that returned to broadcast after 45 years

@ElentirENG ES 7·10·2023 · 23:48 0

Those artificial satellites that resume their communications after being deactivated for a long time are known as "zombie satellites".

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Today half a dozen zombie satellites are known to exist. The second oldest, and the one with a particularly curious history, is the LES-1 (Lincoln Experimental Satellite 1), launched from Cape Canaveral by the United States Air Force (USAF) with a rocket Titan IIIA on February 11, 1965. LES-1 was the first of nine military communications satellites designed by the Lincoln Laboratory of the Massachusetts Institute of Technology (MIT), a program funded by the USAF.

NASA states the following about these satellites and about the LET (Lincoln Experiment Terminals), the ground stations that allowed these satellites to be used:

"The initial program objective was to build, launch, and field a LES and a LET that would work together as a system and demonstrate practical military satellite communications. The availability of Project West Ford's advanced superhigh-frequency (SHF) technology (at seven to eight gigahertz) contributed to the decision to design LES-1 and LET-1 for that band. The Department of Defense's concurrent procurement of a series of SHF satellites and terminals, commencing with the Initial Defense Communications Satellite Program (IDCSP), meant that lessons learned from LES-1 and LET-1 would find an additional application."

NASA notes that LES-1 achieved only some of its goals. Apparently, due to poor circuit wiring, "the satellite never left circular orbit and stopped transmitting in 1967". LES-2, the twin of LES-1, was successful and reached its planned final orbit on May 6, 1965. So, LES-1 was operational for only two years and then fell silent and was never heard from again. of him.

But the LES-1 story did not end there. For decades it orbited the Earth, silent, technically turned into space junk and forgotten amid a tangle of active satellites. On December 18, 2012, Phil Williams, a radio amateur from Cornwall, in South West from England, detected the signal from LES-1, a signal that was verified by radio amateurs from other countries. You can hear that signal here:

It is an enigma how a satellite that was silent for 45 years returned to broadcast. In 2013, Southgatearc.org pointed to a possible explanation: "It is likely that the on board batteries have now disintegrated and some other component failure has caused the transmitter on 237Mhz, to start up when its in sunlight." That website added that LES-1 "is about the size of a small car, It is not likely to re-enter the atmosphere for a long time as the orbit is still relatively high. It poses no threat other than that caused by the thousands of other pieces of space junk in orbit."