NASA’s James Webb Telescope’s big discovery! Uncovers hidden asteroids to bolster efforts to protect Earth from potential impacts

NASA’s James Webb Space Telescope (JWST) is helping scientists better understand near-Earth asteroid impacts by providing unprecedented insights into small asteroids. A team of researchers, led by the Massachusetts Institute of Technology (MIT), repurposed Webb’s observations of a distant star to uncover a previously undetected population of small asteroids orbiting the Sun in the main asteroid belt between Mars and Jupiter. These asteroids, smaller than those traditionally detected by astronomers, provide valuable data for planetary defense. 

The findings could aid NASA’s Asteroid Threat Assessment Project (ATAP), which works to understand the risks associated with asteroid impacts on Earth. By modeling the potential consequences of an impact and the asteroid population, ATAP supports NASA’s Planetary Defense Coordination Office, which is tasked with protecting Earth from asteroid hazards. 

“It’s exciting that Webb’s capabilities can help us study these small asteroids,” said Jessie Dotson, an astrophysicist at NASA’s Ames Research Center and member of ATAP. “By examining the sizes, numbers, and history of smaller main-belt asteroids, we gain crucial insights into near-Earth asteroids and their potential risks.” 

The team discovered 138 new asteroids, ranging from the size of a bus to a stadium — sizes previously undetectable with ground-based telescopes. Understanding the distribution of asteroids in different size categories offers clues about how they’ve evolved over time due to collisions. This information is critical for understanding how some asteroids may have been ejected from the main belt and could potentially pose a risk to Earth. 

“We now have a better understanding of how small objects in the asteroid belt are formed and how many of them there might be,” said Tom Greene, an astrophysicist at Ames and co-author of the research. “These smaller asteroids likely resulted from collisions between larger asteroids in the belt, and some could drift toward Earth’s orbit.” 

This research lays the groundwork for NASA’s upcoming Near-Earth Object (NEO) Surveyor mission, the first space telescope specifically designed to detect and track near-Earth asteroids and comets that could potentially impact Earth. The results of this study were published in Nature on December 9, 2024, in the paper titled "Detections of Decameter Main-Belt Asteroids with JWST.” 

Meanwhile, astronomers are closely monitoring asteroid 2024 XN1, which is set to pass by Earth on December 24. Measuring 120 feet in size, the celestial body will come relatively close to the planet. 

The asteroid will pass at a distance of 4,480,000 miles — over 16 times the distance between Earth and the Moon. It will travel at a speed of 14,743 miles per hour (6.59 km per second) and is expected to make its closest approach at 2:57 am. While the event is considered a ‘near-miss’, scientists confirm that Earth will remain unaffected. 

Study of near-Earth asteroids

The majority of near-Earth objects have orbits that don’t bring them very close to Earth, and therefore pose no risk of impact, but a small fraction of them – called potentially hazardous asteroids – require more attention. These objects are defined as asteroids that are more than about 460 feet (140 meters) in size with orbits that bring them as close as within 4.6 million miles (7.5 million kilometers) of Earth’s orbit around the Sun. CNEOS continuously monitors all known near-Earth objects to assess any impact risk they may pose.  

Near-Earth objects are asteroids and comets with orbits that bring them to within 120 million miles (195 million kilometers) of the Sun, which means they can circulate through the Earth’s orbital neighborhood. Most near-Earth objects are asteroids that range in size from about 10 feet (a few meters) to nearly 25 miles (40 kilometers) across.