Asteroid 2024 YR4, discovered on 27 December 2024 by ATLAS in Chile, made it to the top of our risk list a few days later. Since then, it has been increasing its impact probability for an impact on 22 December 2032, to the point where it has reached a 1.3% impact probability and a Torino Scale value of 3. The situation as of 29 of January has been described in this ESA article. The trajectory of the object can be displayed in the Solar System by means of our Orbit Visualisation Tool and its observability from Earth by means of our Synodic Orbit Visualisation Tool.

We at the NEO Coordination Centre have been quite active since early January in order to obtain as many observations as possible to constrain the trajectory of the object to the best possible. For that purpose with have gathered observations from ESA’s OGS telescope in Tenerife and, thanks to our long-standing collaboration with ESO, we also obtained observations done with the VLT telescopes. We have obtained exquisite astrometry and colour data in order to both improve the trajectory knowledge and the determination of the physical properties of the object. We have used all that data in order to perform recurrent orbit determination and impact monitoring for this object that can be followed in our web portal on a daily basis. Furthermore, we have released a Close Approach Fact Sheet (CAFS) that can be found here.

Thanks to these efforts, and to the efforts of the international asteroid community, the impact threat from this object has been neatly determined. This has been recognised by the release of an IAWN notification speaking of this threat in detail and addressed to the Space Mission Planning Advisory Group (SMPAG) and to the United Nations Office of Outer Space Affairs (UNOOSA). Furthermore, these efforts will be extended in the next weeks until reaching the observability limit from ground for this object in early April 2024.

Under the current conditions the most likely scenario is that the object will be removed from the risk list in the next weeks. However, there is some probability that the object will remain in the risk list until the next apparition starting in mid-2028. Whatever the results, ESA’s Planetary Defence Office will keep a very attentive eye at the evolution of this object.

Ecliptic projection of the trajectory of 2024 YR4 in the Solar System.