Astronomers confused by "space junk" emitting interruptive radio signals

In June 2024, astronomers in Australia detected an unusually powerful radio signal that briefly outshone everything else in the sky. Initially, scientists believed they might have discovered a mysterious astronomical object near Earth. The signal, picked up by the Australian Square Kilometre Array Pathfinder (ASKAP), a powerful radio telescope consisting of 36 massive dish antennas in Western Australia, resembled a “fast radio burst” — a brief, millisecond-long burst of energy typically originating from distant galaxies.

These bursts are thought to possibly come from magnetars, the incredibly dense and magnetically intense remnants of dead stars, and are used by researchers to explore the distribution of matter across the universe. However, excitement among researchers, including Clancy James of Curtin University, quickly turned to confusion when it became clear that the signal was coming from much closer — within Earth’s orbit.

Disappointed but intrigued, an article by CNN documents how the team investigated further and identified the surprising source: Relay 2, a defunct NASA communications satellite launched in 1964. It had ceased functioning by 1967 and had been considered space junk ever since.

The idea that a 60-year-old satellite could suddenly emit a powerful radio signal raised several questions. The team theorized that the satellite may have produced an electrostatic discharge — a sudden release of built-up static electricity. Because Relay 2 was made from early satellite materials not designed to manage electrical charge buildup, it may have been particularly vulnerable to this kind of discharge. The astronomers believe this type of event could be detected with simpler, cheaper instruments than ASKAP, offering new opportunities for monitoring aging satellites and unexplained orbital activity.

This discovery, while fascinating, also highlights a growing problem: space debris. Since the beginning of the Space Age, nearly 22,000 satellites have been launched, with only about half still functioning. The rest contribute to an increasingly hazardous cloud of space junk, including millions of tiny fragments traveling at speeds of up to 18,000 mph. Collisions and interactions among this debris can lead to unexpected effects, such as false signals that interfere with deep-space observations.

James and other researchers warn that as more satellites are launched — including thousands from commercial and government sources — the likelihood of artificial signals mimicking cosmic ones will increase. This interference could compromise radio astronomy’s ability to detect genuine phenomena, such as fast radio bursts from distant galaxies. Experts like Ralph Spencer from the University of Manchester support the team’s findings, noting that similar electrostatic discharges have been detected from modern GPS satellites.

By Nazrin Sadigova