Asteroid 2024 YR4: The 3% Risk That Has NASA Watching—What You Need to Know About 2032's Potential Impact

In recent developments, asteroid 2024 YR4 has garnered significant attention due to its potential to impact Earth in the coming years.

The collision probability was initially estimated at 3.1%, but subsequent observations have reduced this figure to 1.5%. Despite the decreasing likelihood, international space agencies, including NASA and the European Space Agency (ESA), continue to monitor the asteroid closely to refine its trajectory and assess any potential threat.

Asteroid 2024 YR4: An Overview

Discovered on 27th January 2025 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Chile, 2024 YR4 is classified as a near-Earth asteroid. Estimates suggest it measures between 40 and 90 metres in diameter, comparable to the size of a large office building.

An impact from an asteroid of this magnitude could release energy equivalent to approximately eight megatons of TNT, sufficient to devastate a mid-sized city.

Impact Probability and Monitoring Efforts

Upon its discovery, automated asteroid warning systems calculated a 3.1% chance of 2024 YR4 impacting Earth on 22nd December 2032. This initial assessment marked the highest impact probability ever recorded for an object of this size or larger.

However, continuous monitoring and additional observations have since refined this estimate, reducing the impact probability to 1.5%.

The ESA has noted that 2024 YR4 holds the record for the highest impact probability for an asteroid larger than 30 metres since asteroid Apophis in 2004, which briefly had a 2.7% chance of impact.

Global observatories, including the James Webb Space Telescope, are conducting ongoing observations to further refine the asteroid's trajectory. These efforts aim to reduce uncertainties and provide a clearer understanding of the asteroid's path.

Potential Impact Scenarios

While the impact probability has decreased, understanding the potential consequences remains crucial.

An asteroid of 2024 YR4's size could cause significant localised damage upon impact. Historical events, such as the 1908 Tunguska event in Siberia, demonstrate the potential devastation.

In that incident, an object about 50 metres in diameter exploded in the atmosphere, flattening approximately 2,000 square kilometres of forest. A similar impact today could obliterate a major urban area, leading to catastrophic loss of life and infrastructure.

Mitigation Strategies

Space agencies are exploring various mitigation strategies in light of the potential threat. One approach involves deploying a kinetic impactor spacecraft to alter the asteroid's trajectory.

This method aims to nudge the asteroid onto a different path, ensuring it misses Earth. The success of such a mission would depend on several factors, including the asteroid's size, composition, and the amount of warning time before a potential impact.

Another strategy under consideration is the use of explosives to disrupt the asteroid. This approach would involve sending a rocket equipped with explosives to intercept the asteroid, fragmenting it or altering its course. However, this method presents significant challenges, particularly in precisely timing and delivering the explosives to achieve the desired effect.

Public Communication and Future Outlook

Experts emphasise that, despite the initial alarming figures, the current probability of impact remains low. Richard Moissl, head of the ESA's Planetary Defence Office, advised in a report against undue public concern, highlighting that a 1.5% chance still means a 98.5% probability that the asteroid will not impact Earth.

As more data becomes available, the impact probability is expected to continue to decrease. This situation underscores the importance of continued observations and international collaboration in planetary defence efforts.