JWST's Infrared Vision Aids in Detecting and Assessing Potentially Hazardous Asteroids Like 2024 YR4

The James Webb Space Telescope (JWST) is being utilized to enhance planetary defense by detecting and characterizing potentially hazardous asteroids, including the recently discovered 2024 YR4. This capability allows for more precise determination of an asteroid's size, aiding in the assessment of its potential impact risk. While 2024 YR4 is the first notable large asteroid in recent years with a non-negligible Earth impact probability—estimated at 2.1% for a potential collision on December 22, 2032—astronomers are cautious about dismissing even low-probability scenarios. A challenge lies in the fact that many asteroids remain undetected by ground-based telescopes until they are relatively close to Earth. Although 2024 YR4 is not expected to cause a global catastrophe, it could produce significant localized damage. The asteroid, estimated to be between 40 and 90 meters in diameter, was first observed in February 2024. A primary factor influencing the risk assessment of 2024 YR4 is its albedo, or reflectivity. The asteroid's diameter is estimated at 40 meters, but its high surface brightness may give the impression that it is larger. Conversely, if 2024 YR4 does not reflect much light, it could be smaller than initially calculated. Due to these uncertainties, astronomers have proposed using JWST for more accurate size estimations. JWST's infrared detection capabilities can provide more precise measurements of an asteroid's thermal emissions, leading to better diameter estimates than those derived from ground-based optical observations. With current plans, the first round of JWST observations will focus on the brightest asteroid, which will allow the telescope to gather data that NASA and ESA can use to assess its danger and identify potential hazards. JWST is also expected to refine the orbital parameters of 2024 YR4, further assisting astronomers.