Since September, we have known that the asteroid “God Of Chaos” will really approach Earth in 2029. Also known as Apophis, the object formed in the main belt of asteroids between Mars and Jupiter at the beginning of our solar system, approximately 4.6 billion years ago. Discovered in 2004, the asteroid is shaped like a peanut, 375 meters long, and a possible impact with the Earth could level cities and cause considerable natural and human damage!
For now, it is estimated that it will pass approximately 32,000 kilometers from Earth on April 13, 2029, and for a short period, the object will be closer to Earth than telecommunications satellites in geostationary orbit. It will therefore be visible in the night sky with the naked eye from parts of Europe, Africa and Asia.
Its surface evolves as it approaches planets
What is less known is that this passage could modify the very structure of the asteroid. This is what Ronald-Louis Ballouz, an asteroid specialist at the Johns Hopkins University Applied Physics Laboratory, reveals.
In an email sent to our colleagues at Live Science, this astrophysicist explains that the gravitational attraction of the Earth could alter the surface of Apophis in several ways. In an article reread and accepted in the journal The Planetary Science Journaldata extracted from simulations carried out by Ballouz and an international team of researchers show that Apophis' approach could trigger two physical processes.
The first is a series of “tremors” that could shake the asteroid's surface as early as an hour before it reaches its closest point to Earth and continue after that point. Although Apophis's gravity is very weak (about 250,000 times weaker than Earth's), these tremors could be intense enough to move rocks on the surface. If some of these rocks escape the asteroid, the majority would fall back, creating distinct patterns visible from a spacecraft.
Landslides
The second process concerns a change in the oscillation of Apophis. Unlike the regular rotation of the planets, the asteroid oscillates in space irregularly. The simulations show that the Earth's gravitational influence could accelerate or slow down this rotation depending on the orientation of the asteroid during its approach. These changes would affect the rock walls on the surface, which could lead to gradual landslides, but spread over several thousand years.
This research doesn't just predict potential changes to Apophis; they also highlight a mechanism for “refreshing” asteroid surfaces. According to Ballouz, this discovery could answer an old question about how close encounters with planets can transform the surfaces of small celestial bodies.
An asteroid studied closely
NASA's OSIRIS-APEX mission should help confirm these hypotheses. This probe, designed from the OSIRIS-REx mission (known for having collected samples from the asteroid Bennu), will spend 18 months studying Apophis from 2029.
By combining observations from ESA's Ramses mission, which will be near Apophis before and during its approach, with those from OSIRIS-APEX, which will explore the asteroid for months after its passage, astrophysicists will be able to observe and study in detail the changes that occurred on the asteroid following the flyby of the Earth.
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