Scientists plan to land on Apophis, an ominous asteroid set for a rare Earth flyby

They estimate such a flyby only happens once every 20,000 years.


Eric Mack
Dec. 8, 2021 

Artwork of an asteroid approaching Earth. In 2029, Apophis will fly lower than many artificial satellites.NASA

When the stadium-sized asteroid 99942 Apophis comes uncomfortably close to Earth on April 13, 2029, a team of South Korean scientists hopes to greet it in space and bring a sample back to Earth.

Apophis is classified as "potentially hazardous" due to its proximity and size. Earlier this year, NASA ruled out the possibility that the asteroid poses any threat of colliding with Earth when it passes closer to us than the ring of large communications satellites in geostationary orbits.

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Still, scientists see a rare opportunity to study such a large body and also conduct a planetary defense exercise that will be as close to the real thing as humanity has ever seen.

The Korean plan involves approaching Apophis in January of 2029 before it makes its close pass above us. A spacecraft that would launch from Earth in late 2027 would basically accompany the asteroid as it whips by our planet. The plan is to observe and map Apophis the whole way to look for possible changes in its structure as a result of its close encounter with Earth and our planet's gravitational forces.

The Deep Space Network's Goldstone complex in California and the Green Bank Telescope in West Virginia picked up radio images of Apophis from distance of 10.6 million miles (17 million kilometers) away.NASA/JPL-Caltech and NSF/AUI/GBO

"When the gravity has the greatest impact on the asteroid... I think we will have real-time data from the asteroid," explained Young-Jun Choi from the Korea Astronomy and Space Science Institute, who presented the plan at the Korea Space Forum on Monday. "For example, earthquakes or landslides happening on the asteroid."

Choi also mentioned the possibility of landing on the asteroid and taking a sample to return to Earth, similar to Japan's Hayabusa missions and NASA's Osiris-Rex, which have sampled other asteroids.

For the record, Apophis will come within 20,000 miles (32,000 kilometers) of Earth, which is remarkably rare for such a massive object. But there's zero chance of impact.

At a 2020 conference on Apophis and its 2029 visit, the Korean team noted that "with a dedicated rendezvous mission to Apophis, we should be able to fill in the knowledge gaps in our scientific understanding of (gravitational) effects that could be used for planetary defense when there is a real threat."

Earlier this year NASA called the 2029 flyby "an unprecedented opportunity for astronomers to get a close-up view of a solar system relic that is now just a scientific curiosity and not an immediate hazard to our planet."

Choi reiterated that the opportunity to see such a large asteroid up close while it's also so close to Earth is truly rare. He estimates such a flyby only happens once every 20,000 years.

First published on Dec. 7, 2021 at 9:50 a.m. PT.