A forgotten satellite surprised the scientific community by awakening from its long silence with a radio flash so powerful that, for a fleeting moment, it eclipsed the entire night sky.

This extraordinary event was captured on June 13, 2023, when the team of Dr. Clancy James of Curtin University (Australia) was exploring the cosmos with the Australian Square Kilometre Array Pathfinder (ASKAP). ASKAP’s 36 radio telescopes in Western Australia recorded the enigmatic signal that seemed to emerge from the depths of our galaxy, immediately sparking excitement among researchers that they might have discovered an unknown pulsar or other fascinating, as yet uncataloged celestial object. However, upon closer analysis, they discovered something extraordinary: the signal was so close to Earth that ASKAP’s telescopes couldn’t focus on it simultaneously, “like when a camera phone has difficulty focusing on nearby objects,” James explained to New Scientist. This phenomenon indicated that the source must be less than 20,000 kilometers from our planet.

What was most surprising was the brevity and intensity of the pulse: it lasted less than 30 nanoseconds, but was so powerful that it “vastly eclipsed everything else in the sky” for that brief instant, in the words of James, quoted by New Scientist.

When researchers traced the source of the signal and compared it to known satellite positions, they found a single likely culprit: NASA’s Relay 2, an experimental communications satellite launched in 1964 and considered “dead” since 1967. Has the satellite come back to life? Scientists believe something more may be going on.

Relay 2: A space pioneer with a history

Relay 2 was one of NASA’s first functional satellites. Its predecessor, Relay 1 (launched in 1962), had made history as the first satellite to transmit television signals from the United States to Japan and Europe, including tragic coverage of the Kennedy assassination, IFL Science reports.

Relay 2 was launched into orbit in 1964 as an experimental communications device, but NASA stopped using it just a year later, in September 1965. Its transponders continued to function until 1967, when all communications ceased, leaving the metal hull silently orbiting Earth. Until now.

Scientific Theories

What could cause a satellite that has been dead for nearly 60 years to suddenly emit such a powerful signal? Scientists have two main explanations.

The first theory points to electrostatic discharge. Over decades of orbiting in space, Relay 2 could have built up static electricity until it reached a critical point, releasing all that energy all at once in the form of a flash similar to a giant spark.

The second possibility involves a micrometeorite. A small piece of space rock could have hit the satellite, creating a cloud of charged plasma that generated the powerful radio emission detected from Earth.

Karen Aplin, an astrophysicist at the University of Bristol who was not involved in the research, told New Scientist that it would be very difficult to determine which of these scenarios is correct, as both would produce similar radio signals.

Implications for the future of space

This discovery, described in a paper accepted for publication in The Astrophysical Journal and already available to view on ArXiv could have important practical applications. In Aplin's words: “In a world with a lot of space debris and more small, low-cost satellites with limited ESD protection, this radio detection may ultimately offer a new technique for assessing ESD in space.”

The Relay 2 case also reminds us that space is full of surprises. While not technically a “zombie satellite” one that comes back to life after years of inactivity it is part of a fascinating family of space objects that defy our expectations.

The longevity record for a true zombie satellite is held by AMSAT-OSCAR 7, an amateur radio satellite that was presumed dead in 1981 and reappeared 21 years later, in 2002, to everyone’s surprise.