Dead Arecibo Telescope Sends Near-Earth Asteroid Warning From Grave

The final data recording from the Arecibo Observatory, which collapsed in 2020, has warned of a large number of asteroids with the potential of coming near Earth, many of which could be dangerous to life.

According to a paper published on September 22 in the Planetary Science Journal, Arecibo's final stint of data collection between December 2017 and December 2019 reveals observations of 191 near-Earth asteroids, 70 of which may be "potentially hazardous."

Built in Puerto Rico in 1963, the Arecibo Observatory was the largest single-aperture telescope in the world until 2016 when the Chinese Five-hundred-meter Aperture Spherical Telescope (FAST) began operations. It possessed a 1,000-foot-diameter spherical reflector dish designed to detect radio wavelengths from space. It collapsed on itself in late 2020. During its heyday, Arecibo detected up to 124 near-Earth asteroids per year.

Near-Earth asteroids are objects in the solar system that approach the sun at their closest point at a distance less than 1.3 astronomical units (AU), or 1.3 times the distance between the sun and the Earth, according to NASA. One AU is around 93 million miles. If one of these asteroids' orbits crosses the Earth's path, and the object is larger than 460 feet across, it is considered a "potentially hazardous" object or asteroid.

There are over 29,000 known near-Earth asteroids, and around 2,270 known potentially hazardous asteroids, 150 of which are thought to be larger than 0.6 miles in diameter.

According to the paper, the new Arecibo data found several binary asteroids, and one rarely seen "equal-mass" binary asteroid, named 2017 YE5. A binary asteroid consists of an asteroid that closely orbits another, as seen with the binary Didymos-Dimorphos system that was the target of the Double Asteroid Redirection Test (DART) mission in September. An equal-mass binary asteroid system is made of two nearly identical size rocks that are constantly orbiting one another. 2017 YE5 in particular is comprised of two asteroids each measuring around 2,600 and 2,950 feet in diameter.

Despite all these asteroids being located close to Earth, the chances of them colliding with us are extremely low.

"I believe there is no known object that will definitely hit us in a 1,000 years, Thomas Burbine, an astronomer at Mount Holyoke College, told Newsweek. "But we are discovering new objects all the time."

Collisions do occur frequently on a geological time scale: an asteroid impact was responsible for the death of the dinosaurs during the end-Cretaceous extinction around 66 million years ago. This fated asteroid was around 6 miles in diameter and left a 110 mile-diameter crater in the Yucatán Peninsula in Mexico.

"We could expect such an event every few tens of thousands of years—on the timescale of a normal civilisation, a significant risk," Jay Tate, the director of the Spaceguard Center observatory in the U.K., told Newsweek.

Depending on the size, speed and angle of collision of a large asteroid, an impact could have catastrophic effects on Earth.

"At the lower size estimate the immediate effects would take out a reasonably sized country—France for example," Tate said. "At the higher end the destruction would cover a continental sized area. Were it to land in the ocean the whole ocean rim would be subjected to significant tsunami as well as the other effects. The physical destruction would be, of course, only part of the problem, especially in our increasingly globalized society."