Ghost Waves Beneath the Ice: NASA's ANITA Hears What Shouldn't Exist

High above Antarctica, a NASA experiment called ANITA (Antarctic Impulsive Transient Antenna) detected radio waves coming from beneath the ice — at angles around 30° below the surface. That’s a big deal because, according to the Standard Model of particle physics, such signals should be absorbed by thousands of kilometers of rock before ever reaching the surface. Yet, somehow, they made it through.

Initially, scientists thought these might be caused by neutrinos, those ghostly subatomic particles that rarely interact with matter. But the angles and behavior of the signals don’t match what we’d expect from neutrinos. Researchers have ruled out known particle interactions, background noise, and even checked data from other observatories like Pierre Auger in Argentina — still no satisfying.

The unusual radio pulses were detected by the Antarctic Impulsive Transient Antenna (ANITA) experiment, a range of instruments flown on balloons high above Antarctica that are designed to detect radio waves from cosmic rays hitting the atmosphere. (Credit: Stephanie Wissel / Penn State creative commons)

Some theorists are now floating ideas that range from dark matter interactions to new physics beyond the Standard Model. Others suggest we might be seeing an unknown behavior of radio waves near ice or the horizon. A new balloon-based detector called PUEO is expected to launch soon to gather more data and hopefully crack the case.

ANITA was placed in Antarctica because there is little chance of interference from other signals. To capture the emission signals, the balloon-borne radio detector is sent to fly over stretches of ice, capturing what are called ice showers. Credit: Stephanie Wissel / Penn State.

After ANITA's balloon-borne detectors picked up those impossible upward-traveling radio pulses (in both 2006 and 2014), researchers ruled out neutrinos as the cause. The angles were just too steep — around 30° below the horizon — meaning any particle would’ve had to pass through nearly 3,000 km of solid Earth. That’s a feat no known particle can pull off.

To double-check, scientists turned to other observatories like IceCube in Antarctica and Pierre Auger in Argentina. Neither found matching events, reinforcing the anomaly. Theories now range from exotic particles to unknown radio propagation effects near ice or the horizon — but none fully explain the signals.

Enter PUEO — the Payload for Ultrahigh Energy Observations. It’s ANITA’s successor, slated to launch soon with five times the sensitivity. It’ll carry more antennas and upgraded electronics to hunt for similar signals and hopefully determine whether we’re seeing new physics or just misunderstood phenomena.

Stephanie Wissel, a lead physicist on the project, summed it up best:

It's one of those long-standing mysteries. We’ve ruled out what it’s not — now we’re trying to figure out what it is

It’s like the ice is whispering secrets from a realm we haven’t yet mapped. Want to dive deeper into the theories — dark matter, exotic particles, or even the more speculative ones? Follow IndianWeb2.com on X, LinkedIn or Facebook.