ESA Monitoring Potential Threat from Near-Earth Asteroid 2024 YR4

ESA Monitoring Potential Threat from Near-Earth Asteroid 2024 YR4
by Erica Marchand
Paris, France (SPX) Jan 30, 2025

The European Space Agency's (ESA) Planetary Defence Office is closely tracking asteroid 2024 YR4, a newly discovered near-Earth object that has a minimal chance of impacting Earth in December 2032.

Asteroid 2024 YR4 was first detected on December 27, 2024, by the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Rio Hurtado, Chile. Following its discovery, automated asteroid warning systems identified a very small potential for the object to impact Earth on December 22, 2032. With an estimated size ranging between 40 meters and 100 meters, an asteroid of this size would cause significant local damage if it were to collide with Earth, though such impacts occur on average only once every few thousand years.

After its discovery, ESA elevated 2024 YR4 to the top of its asteroid risk list. Since early January 2025, astronomers worldwide have been conducting high-priority follow-up observations, using the new data to refine the asteroid's size and trajectory.

As of January 29, 2025, ESA estimates that the likelihood of asteroid 2024 YR4 colliding with Earth in 2032 is 1.2%. This estimate is consistent with independent assessments from NASA's Center for Near-Earth Object Studies (CNEOS) and the Near-Earth Object Dynamic Site (NEODyS).

Asteroid 2024 YR4 is currently ranked Level 3 on the Torino Impact Hazard Scale, indicating a close encounter that warrants attention from both astronomers and the public. However, it is essential to note that asteroid impact probabilities typically rise initially before quickly declining to zero after further observations.

This asteroid is likely larger than 50 meters, with a higher-than-1% probability of impact within the next 50 years, meeting the criteria for activation of two key UN-endorsed asteroid reaction groups: the International Asteroid Warning Network (IAWN) and the Space Mission Planning Advisory Group (SMPAG).

The International Asteroid Warning Network

Chaired by NASA, IAWN coordinates global organizations involved in asteroid tracking and characterisation. If necessary, IAWN would collaborate with governments to assess the potential consequences of an asteroid impact and recommend mitigation measures. ESA, as a member of IAWN, is actively involved in coordinating observations and updating risk assessments.

The asteroid's orbit around the Sun is elongated (eccentric), and it is currently moving away from Earth in a nearly straight line. This trajectory complicates the determination of its orbit, as the asteroid's motion does not exhibit significant curvature over time.

In the coming months, asteroid 2024 YR4 will begin to fade from view. During this period, ESA will coordinate observations using increasingly advanced telescopes, including the European Southern Observatory's Very Large Telescope in Chile, to gather as much data as possible.

If the asteroid becomes undetectable before its risk can be entirely ruled out, it may remain on ESA's risk list until observations resume in 2028.

The Space Mission Planning Advisory Group

Chaired by ESA, SMPAG facilitates the global exchange of information and collaborates on research and mission development related to near-Earth objects. SMPAG is responsible for planning asteroid threat mitigation activities for asteroid 2024 YR4.

SMPAG is scheduled to meet in Vienna next week to assess the current situation and decide on further actions. If the asteroid's impact probability remains above the 1% threshold, SMPAG will advise the UN and evaluate spacecraft-based response options.