The James Webb Space Telescope (JWST) has been allocated emergency observation time to study asteroid 2024 YR4, which has been classified as potentially hazardous. The space rock was identified in December 2024 and has been placed on the asteroid watch list due to its estimated 2.3% chance of colliding with Earth in December 2032. The emergency decision has been made to improve the accuracy of its size estimation, which is currently based on ground-based observations. Scientists believe that a more precise measurement of its dimensions will provide better insight into the potential risk it poses.

Infrared Observations to Determine True Size

According to reports, the European Space Agency (ESA), the asteroid has an estimated width of 55 metres, but this figure is uncertain due to limitations in ground-based telescopic observations. The asteroid’s brightness has been used to approximate its size, though its actual dimensions may vary significantly depending on surface reflectivity. If the surface is highly reflective, the asteroid could be as small as 40 metres. If it is less reflective, its true size could be as large as 90 metres, significantly altering the potential impact risk assessment.

JWST has been selected for this task due to its ability to capture infrared emissions, which can provide a more accurate measurement of the asteroid’s size and surface composition. Unlike ground telescopes, which rely on reflected sunlight, JWST’s infrared capabilities will detect heat emitted by the asteroid, offering a clearer picture of its actual dimensions. The updated information will play a crucial role in refining impact probability models and informing future planetary defence strategies.

Scheduled Observations and Data Availability

Observations using JWST are planned for March and May. The first session will coincide with the asteroid reaching peak brightness, while the second will take place as it moves away from the Sun. These observations will be conducted using four hours of JWST’s director’s discretionary time, a reserve allocation used for urgent scientific inquiries.

The data collected during these observations will be publicly released once processed. ESA has highlighted the significance of this research, stating that refining the size estimation of 2024 YR4 is essential for determining its potential impact consequences. The results will contribute to ongoing research into near-Earth objects and planetary defence strategies.

Previous Impacts and Potential Consequences

Historical events have demonstrated the damage that asteroids of this size can cause. The Tunguska event of 1908, which flattened an estimated 80 million trees over a vast area of Siberia, is believed to have been caused by an asteroid of similar dimensions. While an impact from 2024 YR4 would not cause mass extinction, the regional consequences could be severe.