The James Webb Space Telescope (JWST), humanity’s most sophisticated orbital observatory, has been urgently redirected to study an alarming celestial threat—asteroid 2024 YR4. Known as a ‘city-killer’, the asteroid has a concerning 2.3% chance of striking Earth, prompting scientists to utilize JWST’s advanced capabilities in an emergency observation campaign.
This asteroid, discovered by NASA’s Asteroid Terrestrial-impact Last Alert System (ATLAS) in December 2024, is currently the focus of intense scrutiny due to its potential to cause significant regional devastation, reminiscent of historical impacts that have reshaped landscapes and climates.
Size and Danger: A Delicate Balance
Initially estimated at approximately 180 feet wide—about the height of the Leaning Tower of Pisa—2024 YR4’s exact dimensions remain uncertain. Ground-based telescopes, hindered by Earth’s atmospheric distortions, can only gauge the asteroid’s size based on the sunlight it reflects. The European Space Agency (ESA) highlighted the importance of obtaining more precise measurements: “It is very important that we improve our size estimate for 2024 YR4: the hazard represented by a 40 m asteroid is very different from that of a 90 m asteroid,” according to an ESA blog post.
A New Perspective from Above
James Webb’s Infrared Advantage
The JWST will employ its cutting-edge infrared capabilities to observe the heat emissions from 2024 YR4, providing a clearer picture of its actual size and surface composition. These observations, scheduled for March and May when the asteroid is at peak brightness and farthest from the sun, respectively, will allow astronomers to bypass the limitations posed by Earth-bound telescopes.
By focusing on the infrared emissions rather than reflected light, JWST will offer new insights into the asteroid’s characteristics. This method not only enhances the accuracy of size measurements but also aids in determining the asteroid’s surface properties, which are crucial for understanding its potential impact threat.
Global Collaboration for a Global Threat
The decision to allocate JWST’s resources to this project underscores the global concern over near-Earth objects. The telescope’s time is highly contested, with astronomers worldwide proposing projects to expand our understanding of the universe. Yet, the director’s discretionary time—reserved for urgent, unforeseen needs—has been designated for these crucial observations.
As 2024 YR4 continues its rapid approach towards Earth, the international astronomical community remains vigilant. The upcoming data from JWST will be vital in assessing the risk posed by this potentially hazardous asteroid. By improving our understanding of its size and composition, scientists can better prepare for any necessary defensive measures to protect Earth.
With every observation, we not only learn more about these celestial neighbors but also enhance our ability to safeguard our planet from future celestial threats. The world watches as JWST takes on this critical mission, hoping that with advanced warning, humanity will never face a repeat of the catastrophic events that have marked our planet’s past.