The Asteroid That Will Be Forever Changed By Passing Near Earth

As far as astronomers know, there are more than 1.4 million asteroids in our solar system, and most of them orbit the sun in the asteroid belt between Mars and Jupiter. They can range in size from just a few feet to 329 miles in diameter, and anything larger than 460 feet wide and within about 4.68 million miles of Earth is considered a potentially hazardous object. That's why asteroid 99942 Apophis, which is about 1,100 feet across, caused such a stir when it crossed NASA's radar in 2004. But, what was believed to be a risk to our planet is actually at risk from us.

During its flyby on April 13, 2029, Apophis will be less than 24,000 miles from the Earth's surface, bringing it within view of the naked eye. At this distance, it will be much closer than the closest the devil comet has come to Earth, the asteroids that have temporarily become second moons, the Moon itself, and even our furthest orbiting telecommunications satellites. A study published in The Planetary Science Journal revealed that, based on simulated models, this is close enough to our planet for strong tidal forces to have an impact on Apophis. The asteroid will likely experience landslides and quakes, distorting it into a slightly different shape. Also, Earth's gravity will likely change its rotation and widen its orbit so much that it will move from the Atens group of asteroids to the Apollo group.

At the time of initial discovery, astronomers thought that Apophis might strike Earth in 2029, which would cause catastrophic damage. After a more precise analysis in 2021 by the Jet Propulsion Laboratory's Center for Near-Earth Object Studies, which estimates the orbits of asteroids, they determined that the asteroid won't pose a threat to us for a century at least. Through a supportive partnership with NASA's Planetary Defense Coordination Office, the agencies plan to continue tracking and studying the asteroid as part of their overall goal to help future generations prepare a defense plan for eventual impact. And, the European Space Agency (ESA) is getting in on this action, too.

Through its Rapid Apophis Mission for Space Safety (dubbed Ramses), the ESA plans to launch a spacecraft in April 2028 to meet the asteroid in February 2029, giving it two months to survey the orbit, orientation, rotation, shape, and surface. Scientists will also be able to learn about its cohesion, composition, density, interior structure, mass, and porosity. Meanwhile, NASA has already redirected its OSIRIS-REx spacecraft (renamed OSIRIS-Apophis EXplorer or OSIRIS-APEX) to meet up with Apophis one month after the flyby to study the aftermath of Earth's gravitational pull. Additionally, having two spacecraft at the asteroid will open the door for measuring long-term effects and conducting more investigations for months after contact.