Study finds the “God of Chaos” asteroid could be reshaped by tremors and landslides during Earth’s 2029 flyby

Landslides and aftershocks can change the situation asteroid Apophis during its contact with Earth in 2029, according to a new study.

Named after Apep, the ancient Egyptian god of chaos. Apophis is an 1,100-foot (340-meter) long asteroid shaped like a peanut. Although an impact with a space rock of this size would not destroy our planet, it can easily destroy a city.

When Apophis was discovered in 2004, astronomers estimated that it could pass very close to Earth in 2029. More detailed observations in 2021 allowed scientists to pinpoint Apophis’ path with greater precision, revealing that it had less chance of colliding with Earth than researchers originally thought. . Apophis is currently forecast to pass within 20,000 miles (32,000 kilometers) of Earth on April 13, 2029, closer to it than some artificial satellites.

Given this distance, Apophis likely won’t have much of an impact on Earth in 2029. But how will the asteroid itself behave after such a close encounter?

This question intrigued me Ronald-Louis Ballouzasteroid researcher at the Johns Hopkins University Applied Physics Laboratory. Tiny meteoroids constantly bombard the surfaces of asteroids in a process called space weathering, Ballouz told Live Science in an email. However, Ballouz added that astronomers have long noticed that asteroids that pass close to planets like Earth often lack weathered surfaces.

The exact physical mechanism that removes traces of weathering is little known, Ballouz said. One possibility is that the planet’s gravity pulls on rocks on the asteroid’s surface, throwing them away and exposing the underlying layer.

To test this hypothesis, Ballouz and a team of international researchers created computational models of Apophis. Little is known about the asteroid’s physical characteristics, so the researchers based their models on a similar two-lobed asteroid. Itokawawhich has been studied in more detail. The researchers then simulated each model’s movement toward Earth, tracking both large-scale and small-scale physical changes.

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Rendering of an oblong asteroid

An image of the lobed asteroid Itokawa, which was used as a proxy for the asteroid Apophis in the new study. (Image credit: ESA)

Researchers have found that two physical processes caused by Earth’s gravitational pull are likely to change the surface of Apophis during its 2029 encounter. One of them is tremors that will likely begin an hour before Apophis reaches its closest point to Earth and continue for some time after that.

The strength of the tremors is difficult to estimate, Ballouz said. However, “Apophis’s gravity is about 250,000 times less than Earth’s,” he added. “So we think that events on a much smaller scale could really shake things up on its surface.”

This means that earthquakes could be strong enough to lift boulders from the surface of Apophis. While some rocks may escape, most will fall back onto Apophis, creating distinct patterns on the surface that a passing spacecraft can identify.

Another process that could “refresh” the surface of Apophis is a change in its position. Flipping occurs because the asteroid is not rotating around a fixed axis or period of time; instead, he tumbles through space like a poorly thrown soccer ball.

Unrelated 2023 study showed that Earth’s gravity will cause the asteroid to spin either faster or slower, depending on its orientation, as it approaches 2029. New modeling confirmed this conclusion. They also found that changes in the dip of Apophis would destabilize the inclined faces of surface rocks, which in extreme cases could cause landslides. Unlike seismic shaking, these changes will occur gradually over tens of thousands of years.

The results don’t just predict how Apophis will behave after the impact in 2029. According to Balloues, “They present a new mechanism for resurfacing asteroids that may provide an answer to the long-standing problem of how close planetary encounters can change the surfaces of small bodies.”

Ballouz and his colleagues hope that NASA‘s OSIRIS-APEX The mission will confirm their hypotheses. Repurposed from OSIRIS-REx – a spaceship that took samples from the asteroid Bennu — OSIRIS-APEX plans to study Apophis during a meeting in 2029. It will meet with the asteroid for 18 months to study its chemical composition and map its surface.

The study is currently available on the website arXiv preprint databasehas been accepted for publication in The Planetary Science Journal.