A satellite signals after 45 years of radio silence

Lincoln Laboratory developed a system to record signals from the first of the Lincoln Experimental Satellites after it mysteriously began retransmitting data in 2012.
June 12, 2024
Ariana Tantillo | Communications & Community Outreach Office

A deactivated satellite resuming communications after decades of silence may sound like science fiction, but for Lincoln Experimental Satellite (LES)-1, it's reality. In 2012, amateur radio operators detected a telemetry signal from LES-1, long thought to be dead, at the ultrahigh frequency of 237 MHz.

Engineers inspect LES-1 prior to its 1965 launch. The satellite is positioned atop a Titan III rocket on the launch pad at Cape Kennedy, Florida.
Engineers inspect LES-1 prior to its 1965 launch. The satellite is positioned atop a Titan III rocket on the launch pad at Cape Kennedy, Florida.

Launched into orbit in February 1965, LES-1 — the first in a series of satellites developed by Lincoln Laboratory over nearly two decades to support military needs for reliable, long-range connectivity — had shut down its transmitter in 1967, at the end of its intended lifetime. For the next 45 years, not a peep came from LES-1. What then caused LES-1 to spontaneously start transmitting again after so many years of radio silence? Though we don't know for certain why this "zombie" satellite came back to life, one possibility is that LES-1 experienced an electrical short (caused by its batteries or circuitry degrading over time), allowing power from its solar cells to directly reach the transmitter.

A team from Lincoln Laboratory recently developed a system to record LES-1 signals every time the satellite passes over the Laboratory's main campus in Lexington, Massachusetts. An automated rooftop antenna records the signals transmitted from LES-1 when the satellite initially comes into view, is at its highest point in the sky, and is going over the horizon. An interactive tool allows users to see the orbit and approximate position of LES-1 at the time of each recording.

"LES-1 is one of the oldest satellites in space and part of Lincoln Laboratory's legacy in SATCOM [satellite communications], so to see it still transmitting after all these years is remarkable," says Navid Yazdani, leader of the Laboratory's Advanced SATCOM Systems and Operations Group. "LES-1 introduced several innovative SATCOM technologies and techniques for its time, and lessons learned during the launch and testing of LES-1 enabled engineers to refine the design of subsequent experimental satellites that paved the way for future military and civil systems."

For the complete history of the LES series, visit the LES website.

Inquiries: contact Ariana Tantillo.