Nearly 50 years after its loss, the LES-1 “zombie satellite” began sending signals back to Earth

These were the first very high frequency satellites using the X band of the electromagnetic spectrum.

“The Lincoln Laboratory Space Communications Program after the West Ford Project began in 1963 with a charter to build and demonstrate military space communications systems. The initial goal of the program was to construct, launch, and field a LES and a LET (Lincoln Experimental Terminals) that would operate together as a system and demonstrate practical military satellite communications,” explains the Lincoln Historical Office. NASA about the project, which had mixed success.

“LES-1, launched from Cape Canaveral on February 11, 1965, achieved only a few of its objectives,” adds NASA. “Apparently, due to poor wiring of the munitions circuits, the satellite never left its circular orbit and ceased transmitting in 1967. LES-2, LES-1’s twin, fared much better; it reached its final scheduled orbit on May 6, 1965.”

LES-1, no longer sending any signals, continued its orbit around Earth for nearly half a century, another dead space debris littering Earth’s orbit. But in 2013, an amateur radio astronomer in Cornwall, UK, picked up a signal that could only come from LES-1. It had become what we call a “zombie satellite”; satellites which – sometimes mysteriously – become active again.

According to Phil Williams, who found the space zombie, the signal coming from the satellite was fading in a four-second loop. He attributed this to the fact that LES-1 was falling every four seconds, with the engines blocking its solar panels.

“This makes the signal sound particularly ghostly because the voltage from the solar panels fluctuates,” Williams said at the time.

After the satellite came back to life, a team from Lincoln Laboratory set up a system to record LES-1 every time it flew over the main university campus.

“LES-1 is one of the oldest satellites in space and part of Lincoln Lab’s SATCOM (satellite communications) legacy, so to see it still transmitting after all these years is remarkable,” Navid Yazdani, head of the Laboratory’s Advanced SATCOM Systems and Operations Group, said in a statement. “LES-1 introduced several innovative SATCOM technologies and techniques for its time, and the lessons learned during the launch and testing of LES-1 allowed engineers to refine the designs of subsequent experimental satellites that paved the way for future military and civilian systems.”

So what caused this satellite to go into zombie mode? We’re not entirely sure, but of course there’s nothing to worry about.

“Although we do not know for sure why this ‘zombie’ satellite came back to life, it is possible that LES-1 suffered an electrical short (caused by its batteries or circuitry degrading over time), allowing energy from its solar cells to reach the transmitter directly,” explains Lincoln Laboratory.

The satellite remains in orbit and operational to this day.