A team of researchers working in Antarctica has detected unusual radio signals emerging from deep beneath the ice. These waves were picked up during an experiment using the Antarctic Impulsive Transient Antenna (ANITA), a NASA-funded project that searches for high-energy particles from space. The discovery was unexpected as the signals appeared to be coming from below the surface rather than from space. Scientists say the waves are unlikely to be caused by known particles like neutrinos and have yet to determine exactly what is producing them.

Radio waves found during neutrino search in Antarctica

The ANITA experiment was designed to study high-energy neutrinos using a balloon that carried radio instruments into the stratosphere. Antarctica was chosen as the site due to its isolation and low interference from other radio sources. While searching for neutrinos researchers came across signals coming from around 30 degrees below the ice surface. These signals were unexpected because they would have had to pass through thousands of kilometres of rock which should have absorbed them completely.

Neutrinos ruled out as the cause

Stephanie Wissel, an astrophysicist at Penn State University and part of the ANITA team, explained that the signals were not consistent with neutrinos. Neutrinos are incredibly difficult to detect and rarely interact with matter. Although they can travel great distances through solid rock the angles and nature of the signals did not match what scientists expect from neutrino interactions. The team also cross-checked their findings with data from two other experiments and found no matches confirming that these were not neutrino events.

Theories and unanswered questions around the mystery

Since neutrinos were ruled out scientists are now considering other explanations. Some have proposed the signals could be related to dark matter or unknown radio wave behaviour around the ice and the horizon. However none of these theories have been confirmed. Wissel said that while they have explored several ideas none fully explain what was detected. She added that more experiments and data will be needed to understand what is happening under the Antarctic ice.

Search continues for the mysterious source

The instruments used in the experiment were lifted about 40 kilometres into the sky to capture faint radio emissions. While this approach allows for a broad view of signals entering Earth from space it also reveals unexpected activity from below. As scientists continue to review the data and prepare for future missions they hope to uncover more about the nature of these strange signals. For now the source of the radio waves remains a mystery.