Astronomers receive powerful radio signal only 4,500 km away from Earth: Here’s what they find next
In June 2024, astronomers in Australia detected a powerful radio signal that seemed to come from near Earth. At first, they thought it was a new space object.
The signal was picked up by the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope in Western Australia. It was so strong it outshone everything else in the sky for a moment.
Researchers usually look for fast radio bursts: short, powerful signals from faraway galaxies, possibly caused by dense, magnetic remains of dead stars.
However, this signal was different. When they focused the telescope, the short signal became extremely bright, around 2,000 to 3,000 times stronger than any other signals recorded.
The team removed data from the outer antennas and used the central ones to study it better. It came from only 4,500 km away and matched the location of an old satellite called Relay 2.
NASA launched Relay 2, a communication satellite, in 1964 to improve signals between the US and Europe and help broadcast the Tokyo Olympics. But, by 1967, it stopped working and became space junk.
Though disappointed it wasn’t from space, scientists were left wondering what exactly created such a strong signal. The incident raised new concerns about space junk in Earth’s orbit.
What caused the signal?
Scientists think the signal may have come from a sudden release of static electricity that built up on the satellite’s metal surface. It is similar to when you rub your feet on a carpet and get a small electric shock.
Another possible cause is a tiny micrometeorite hitting the satellite at very high speed, which could create a burst of hot gas (plasma) and send out a short radio wave.
Although this second reason is less likely, it still shows how even dead satellites in space can sometimes give off unexpected signals after decades of silence.
With growing numbers of old satellites, signals like this might become more common and may interfere with important space research in the future, Professor Clancy James told CNN.
