Astronomers analyzing archival images from the James Webb Space Telescope (JWST) have identified an unexpectedly vast population of tiny asteroids in the asteroid belt between Mars and Jupiter. The breakthrough, achieved through advanced infrared imaging and computational techniques, marks a significant leap in our ability to detect small but powerful space rocks that could potentially approach Earth.
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Led by a team from the Massachusetts Institute of Technology (MIT), the discovery has pushed the detection threshold to objects as small as 10 meters (33 feet) in diameter. Previous surveys were limited to asteroids around 1 kilometer (0.62 miles) wide, leaving a significant portion of the asteroid population undetected.
Probing the Smallest Asteroids
The newly detected asteroids, ranging from the size of a bus to several stadiums, are the tiniest yet discovered in the main asteroid belt. While small compared to the massive space rock that wiped out the dinosaurs, these “decameter” asteroids are far from harmless. A decade ago, an asteroid just tens of meters wide exploded over Chelyabinsk, Russia, releasing 30 times the energy of the Hiroshima atomic bomb.
These small asteroids collide with Earth 10,000 times more frequently than larger ones. However, their small size and faint visibility make them difficult to detect in advance, posing a challenge for planetary defense efforts.
Cutting-Edge Technology and Methods
The discovery was made possible by a computationally intensive method called “shift and stack,” which aligns and combines multiple images to amplify faint, fast-moving objects like asteroids. Researchers applied this technique to thousands of JWST images of the TRAPPIST-1 system, a planetary system located about 40 light-years from Earth.
Using powerful graphics processing units (GPUs), the team rapidly processed over 10,000 images, identifying 138 new asteroids alongside eight previously known ones. Julien de Wit, an associate professor of planetary science at MIT, highlighted the significance of this breakthrough: “We thought we would just detect a few new objects, but we detected so many more than expected — especially small ones.”
Game-Changer
The JWST’s sharp infrared sensitivity played a crucial role in the discovery. Unlike traditional visible-light surveys, which rely on sunlight reflected off asteroids, infrared imaging detects the thermal emissions of these objects. This allows for better size estimation and the detection of faint asteroids that might otherwise go unnoticed.
Implications for Planetary Defense
The ability to track these smaller asteroids is critical for early warning systems. Even asteroids as small as 10 meters can cause regional devastation, as demonstrated by the 1908 Tunguska event in Siberia. Detecting these objects earlier allows for more precise orbital tracking, which is vital for planetary defense. “This is a totally new, unexplored space we are entering, thanks to modern technologies,” said Artem Burdanov, a research scientist at MIT.
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Future observations with JWST and other cutting-edge telescopes, such as the Vera C. Rubin Observatory in Chile, are expected to uncover thousands more small asteroids. The Rubin Observatory, set to begin operations next year, will scan the southern sky nightly, potentially doubling the known asteroid catalog within six months.