Science

Avoiding Collision With Earth

In 2029 a large asteroid will be passing closer to the Earth than many of our satellites do. The event is the stuff of science fiction movies but so are moves to increase our understanding and how the planet could be defended against ‘close encounters’.

The High-frequency Active Auroral Research Program (HAARP) research site in Gakona, Alaska will attempt to bounce a radio signal off an asteroid on December 27th this year to see what can be learned.

This is the first time HAARP will be used for this kind of experiment. It will transmit radio signals to asteroid 2010 XC15, which could be about 500 feet across. The University of New Mexico Long Wavelength Array near Socorro, New Mexico, and the Owens Valley Radio Observatory Long Wavelength Array near Bishop, California, will receive the signal.

Knowing more about an asteroid’s interior, especially of an asteroid large enough to cause major damage on Earth, is important for determining how to defend against it.

 Mark Haynes, lead investigator on the project and a radar systems engineer at NASA’s Jet Propulsion Laboratory in Southern California explained:

“What’s new and what we are trying to do is probe asteroid interiors with long wavelength radars and radio telescopes from the ground.

 “Longer wavelengths can penetrate the interior of an object much better than the radio wavelengths used for communication.

“If you know the distribution of mass, you can make an impactor more effective, because you’ll know where to hit the asteroid a little better.”

The test on 2010 XC15 is yet another step toward the globally anticipated 2029 encounter with asteroid Apophis. It follows tests in January and October in which the moon was the target of a HAARP signal bounce.

These images of asteroid Apophis were recorded in March 2021 by radio antennas at the Deep Space Network’s Goldstone complex in California and the Green Bank Telescope in West Virginia. The asteroid was 10.6 million miles (17 million kilometres) away from Earth. Credit: NASA/JPL-Caltech and NSF/AUI/GBO

Apophis was discovered in 2004 and will make its closest approach to Earth on April 13, 2029, when it comes within 20,000 miles. Geostationary satellites orbit Earth at about 23,000 miles. The asteroid, 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.

NASA says an automobile-sized asteroid hits Earth’s atmosphere about once a year, creating a fireball and burning up before reaching the surface.

About every 2,000 years a meteoroid the size of a football field hits Earth. Those can cause a lot of damage. And as for wiping out civilisation, NASA says an object large enough to do that strikes the planet once every few million years.

NASA first successfully redirected an asteroid on Sept. 26, when its Double Asteroid Redirection Test mission, or DART, collided with Dimorphos. That asteroid is an orbiting moonlet of the larger Didymos asteroid.

The DART collision altered the moonlet’s orbit time by 32 minutes.

The Dec. 27 test could reveal great potential for the use of asteroid sensing by long wavelength radio signals. Approximately 80 known near-Earth asteroids passed between the moon and Earth in 2019, most of them small and discovered near closest approach.

The National Science Foundation is funding the work through its award to the Geophysical Institute for establishing the Subauroral Geophysical Observatory for Space Physics and Radio Science in Gakona.

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