Amateur radio operators around the world heard an Alaskan science facility “chirp” an asteroid.

On Twitter, ham radio users published audio and video of a Tuesday experiment from the High-frequency Active Auroral Research Program, or HAARP. This research facility is a project from the University of Alaska, and is located about a four-hour drive northeast from Anchorage, near a place called Gakona. From this remote place, home to just 169 individuals, HAARP got in touch with an asteroid.

By firing a “chirp” radio signal in two-second intervals, astronomers with HAARP sought to learn about the interior of asteroid 2010 XC15. It’s an Aten-family asteroid, a class of Near-Earth Asteroids (NEAs) that crosses our planet’s orbit but chiefly dwell closer to the Sun. While 2010 XC15 doesn’t pose a risk to Earth, HAARP wanted to learn about this rock’s interior. The information could show how long wavelength radio signals can probe the inside of an asteroid, which can improve models of rocks that could be dangerous. In 2029, with preparations in hand, HAARP will observe a more-concerning asteroid named Apophis.

This was the first use of HAARP to probe an asteroid, the University of Alaska Fairbanks states in an announcement published December 21.

“What’s new and what we are trying to do is probe asteroid interiors with long wavelength radars and radio telescopes from the ground,” Mark Haynes, HAARP lead investigator and a radar systems engineer at NASA’s Jet Propulsion Laboratory in Southern California, says in the statement. “Longer wavelengths can penetrate the interior of an object much better than the radio wavelengths used for communication.”

HAARP may be the way forward to tackling bigger rocks. The moonlet, Dimorphos, was 525 feet in diameter in size, just slightly larger than HAARP’s target. Apophis, however, is twice as big.