A NASA satellite that had remained inactive in orbit for nearly six decades suddenly emitted a powerful radio signal, leaving astronomers around the world stunned.
The brief but intense signal, detected by radio telescopes in Western Australia, lasted only a fraction of a second yet became the brightest object in the sky, momentarily outshining entire galaxies and stars.
The source of this unexpected burst was Relay 2, a communications satellite launched by NASA in 1964.
After both of its transmitters failed in 1967, the satellite had been silent and declared defunct until now.
Experts believe the signal wasn’t deliberately transmitted by the satellite, but was triggered by an external event.
One possibility is an electrostatic discharge: a sudden release of electrical energy, similar to a spark, caused by the satellite building up charge as it orbits through Earth’s magnetic field.
Another theory is that a micrometeoroid, a tiny piece of rock traveling at high speed, struck Relay 2, causing a burst of heat and charged particles that emitted the brief but intense signal.
The burst briefly emitted about 400 watts of power, similar to a small microwave oven. The fact that this signal remained that powerful after traveling from space to Earth makes it especially rare.
Relay 2, a NASA communications satellite launched in 1964.
Australian scientists, who were scanning the sky for fast radio bursts (FRBs)—short, high-energy flashes typically originating from deep space—made the startling discovery.
According to NASA, FRBs can briefly outshine entire galaxies, a phenomenon that occurs in the blink of an eye.
However, this signal was unique: it originated not from a distant galaxy but from within Earth’s orbit, just about 2,800 miles above the planet’s surface.
‘We thought we might’ve found a new pulsar or a never-before-seen object,’ Dr. Clancy James, lead researcher and associate professor at Curtin Institute of Radio Astronomy, told New Scientist.
‘Instead, we saw an incredibly powerful radio pulse that eclipsed everything else in the sky for a split second.’
The burst was detected by the Australian Square Kilometer Array Pathfinder (ASKAP), a network of 36 radio telescopes.
Researchers quickly traced the source to Relay 2, which happened to be passing overhead at that exact moment.
Despite lasting only nanoseconds, the radio burst was extraordinarily strong. Scientists estimated its strength at more than three million janskys, a unit used to measure radio wave intensity.
Australian scientists made the discovery while scanning the sky for fast radio bursts (FRBs) , short, high-energy flashes that typically originate from deep space (STOCK)
That’s roughly 100 billion times stronger than the radio signals from your typical smartphone.
The shape of the signal was clean and well-defined, allowing scientists to analyze it in detail.
Relay 2 was originally launched to improve satellite communication and conduct studies on Earth’s radiation belts, areas filled with charged particles trapped by the planet’s magnetic field.
It carried two transmitters and was designed to spin for stability. But by mid-1967, both transmitters had failed, and the satellite became just another piece of space junk orbiting Earth.
At first, researchers thought the detected signal came from a distant cosmic object. But a closer look confirmed it aligned exactly with Relay 2’s position in the sky.
‘This must have been caused by an external trigger, like an electrostatic discharge or a micrometeorite hit,’ Dr. James explained.
The burst lasted 1,000 times faster than previous electrostatic signals detected from satellites, which typically last a microsecond (one-millionth of a second).
This makes it the fastest and most powerful signal of its kind ever recorded near Earth.
While the signal caused a stir in the astronomy world, it also raised concerns.
Many telescopes scan the sky for signals from far-off galaxies, and an unexpected burst from a nearby defunct satellite could cause confusion or lead to false discoveries.
Still, some scientists see a silver lining. Dr Karen Aplin, a space weather expert at the University of Bristol, said this surprise detection could lead to new tools for studying electrical activity in space.
‘It may ultimately offer a new technique to evaluate electrostatic discharges in orbit,’ she said.
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