[News in Numbers] 138 Small Asteroids Measuring Dozens of Meters Discovered

Sixty percent of Earth's species, including dinosaurs, went extinct 66 million years ago. The direct cause of the dinosaur extinction is attributed to an asteroid impact. It is estimated that a massive impactor named 'Chicxulub' collided with the Yucatan Peninsula in Mexico. Asteroid impacts are considered one of the events that could potentially bring about the end of humanity someday. The asteroid that caused the dinosaur extinction was about 10 km in size. Such impacts are expected to occur once every 100 million to 500 million years. Scientists believe that smaller asteroids, about the size of a bus, collide every few years and can cause localized damage. In fact, the meteor that exploded over Chelyabinsk, Russia, in 2013 was estimated to be about 20 meters in size, and despite the airburst, it damaged hundreds of buildings and caused over 1,000 casualties. The meteor that caused the Tunguska explosion in Siberia in 1908 was known to be at least 50 meters in size, devastating an area more than three times the size of Seoul.

An illustration depicting the observation of small asteroids in the asteroid belt using the James Webb Space Telescope (JWST).
[Photo by Ella Maru]

Worldwide efforts are underway to observe and track Near Earth Asteroids (NEAs).

A U.S. research team recently developed a detection method capable of identifying small asteroids tens of meters in size in the main asteroid belt located between Mars and Jupiter, about 250 million km away, and discovered 138 new asteroids.

On the 10th, Professor Julien de Wit’s team at the Massachusetts Institute of Technology (MIT) announced through the scientific journal Nature that they analyzed infrared observation data from the James Webb Space Telescope (JWST), which is used to search for exoplanet atmospheres, and identified 138 asteroids between 10 m and 100 m in size in the main asteroid belt.

According to the research team, the smallest asteroid discovered so far in the asteroid belt was about 1 km in diameter. The new research method can detect asteroids as small as 10 m in diameter, which the team expects will contribute to defending Earth from asteroid impacts. The millions of asteroids in the main asteroid belt between Mars and Jupiter are scientifically important observation targets because they not only are the origin of meteorites falling to Earth but also contain information about the formation process of the solar system. Since the first asteroid was discovered in 1801, about 750,000 asteroids have been identified in this belt.

In this study, the research team focused on JWST data observed with a high-sensitivity infrared instrument to determine whether exoplanets discovered around the ultra-cool red dwarf TRAPPIST-1, located 44 light-years away, have atmospheres. Some of the seven planets in the TRAPPIST-1 exoplanet system are estimated to be in the habitable zone where liquid water and potentially life could exist. The team applied a 'shift and stack' technique, which combines multiple images to reveal faint objects, to over 10,000 JWST images focused on these planets.

While asteroids within the solar system are considered 'noise' that interferes with observations of distant stars by ground-based telescopes and space telescopes like JWST, the team found a way to capture small asteroids hidden in this noise using advanced image processing techniques. By analyzing the noise in JWST infrared observation images, the team confirmed eight previously known asteroids around the asteroid belt and discovered 138 new asteroids through further analysis. The team also stated that some of the 138 newly discovered asteroids are estimated to have orbits that could potentially bring them close to Earth.