Asteroid Apophis, discovered in 2004, will make its closest approach to Earth on April 13, 2029. It will come within about 20,000 miles of Earth, closer than the many geostationary satellites orbiting the planet.

Apophis, which NASA estimated to be about 1,100 feet across, was initially thought to pose a risk to Earth in 2068, but its orbit has since been better projected by researchers and is now not a risk to the planet for at least a century.

At the end of 2022 a test following on from tests in January and October took place in which scientists bounced long-wavelength signals off the moon.

Link to previous article: Avoiding Collision With Earth

The results will not be known for some time but amateur scientists from around the world reported receiving the outgoing transmission which will aid with the research.

At the High-frequency Active Auroral Research Program (HAARP) research facility at Gakona, Alaska, a powerful transmitter sent long wavelength radio signals into space with the purpose of bouncing them off an asteroid to learn about its interior. The University of New Mexico Long Wavelength Array near Socorro, New Mexico, and the Owens Valley Radio Observatory Long Wavelength Array near Bishop, California, are also involved in the experiment.

The information from this experiment could aid efforts to defend Earth from larger asteroids that could cause significant damage – like Apophis.

Several programs exist to quickly detect asteroids, determine their orbit and shape and image their surface, either with optical telescopes or the planetary radar of the Deep Space Network, NASA’s network of large and highly senstive radio antennas in California, Spain and Australia.

Those radar-imaging programs don’t provide information about an asteroid’s interior, however. They use signals of short wavelengths, which bounce off the surface and provide high-quality external images but don’t penetrate an object. 

Long wavelength radio signals can reveal the interior of objects. 

HAARP, using three powerful generators, began transmitting chirping signals of long wavelength and continued sending them uninterrupted until the scheduled end of the 12-hour experiment.

Knowing the distribution of mass within a dangerous asteroid could help scientists target devices designed to deflect an asteroid away from Earth.

Jessica Matthews, HAARP’s program manager explained:

“Our collaboration with JPL [NASA’s Jet Propulsion Laboratory] is not only an opportunity to do great science but also involves the global community of citizen scientists.

“So far we have received over 300 reception reports from the amateur radio and radio astronomy communities from six continents who confirmed the HAARP transmission.” 

The University of Alaska Fairbanks operates HAARP under an agreement with the Air Force, which developed and owned HAARP but transferred the research instruments to UAF in August 2015.