Location of possible meteorites for the NEA 2024 XA1

The asteroid 2024 XA1, a meter-sized object which impacted Earth on 3 December 2024 at 16:15 UTC over a remote area of the Sakha Republic (Russia), was discovered only a few hours before impact. The impact alert was first announced by Meerkat (Gianotto et al. 2023), the imminent impactor warning service operated at the NEO Coordination Centre* (NEOCC) by ESA. At the epoch of the alert, the asteroid was still on the NEO Confirmation Page** (NEOCP) of the Minor Planet Center*** (MPC). As soon as sufficient observations were available, a more accurate orbit determination and impact corridors were computed with the ESA Aegis Orbit Determination and Impact monitoring system (Fenucci et al. 2024). The impact point at 100 km altitude was used to compute the possible strewn fields, even before the impact epoch, and it was performed by the Italian Istituto Nazionale di Astrofisica (INAF).

Determining 2024 XA1 strewn field

In a recent paper (Carbognani et al. 2025) we have shown that starting at 100 km altitude and using a simple small asteroid fall model, it was possible to identify the strewn field of the fall events of 2023 CX1, 2024 BX1, and the historical case of 2008 TC3. The strewn field was determined with uncertainties of the order of a kilometre, a distance easily covered by walking on the ground.

The fall model considers only a single fragmentation followed by a release of fragments of different fixed mass, all with the same speed and direction and without a lateral speed component. A real wind profile is also included in the model. Initial data on the asteroid’s position and speed at 100 km altitude are derived directly from the heliocentric orbit elements available from telescope observations, without the need for triangulation of the fireball phase. Because of the possibility of estimating the position of the fragment fall
zone before the small asteroid hits the Earth, we called this computation the “ab initio strewn field” model.

2024 XA1 meteorites potentially close to Kiliyer village

According to the model results, with an average strength of S = 0.5 MPa, the main fragmentation occurred at 40.6 km altitude, a value that drops to 35.6 km for 1 MPa and 23.7 km for S = 5 MPa. For all three possible strength cases, the geographic coordinates of the starting point of the dark flight of the possible fragment with a final mass of 1 kg are Lat. 61.1° E, Long. 119.8° E. Due to the high inclination of the trajectory, the three possible strewn fields largely overlap, which is an advantage for ground research, see Figure 1. The potential 0.5 MPa strewn field has a ground length of 10 km, a value that drops to 6 km for the 5 MPa one because the dispersion of the fragments began at a lower height, so these are walking distances.

The possible strewn fields are located about 13 km before the theoretical impact point without considering the atmosphere, 37 km northeast of Kiliyer village, 89 km north of the city of Olekminsk and 950 km east of Tunguska’s epicentre. From Google Maps, the area appears to be covered by Taiga vegetation, so searching on the ground will not be easy. Still, we hope some fragments can be recovered in future search campaigns.

References

Carbognani, A., Fenucci, M., Salerno, R., & Micheli, M. 2025, Icarus, 425, 116345
Fenucci, M., Faggioli, L., Gianotto, F., et al. 2024, Celestial Mechanics and Dynamical Astronomy, 136, 58
Gianotto, F., Frühauf, M., Cano, J. L., et al. 2023, in 2nd NEO and Debris Detection Conference, 49

Notes

* https://neo.ssa.esa.int/
** https://www.minorplanetcenter.net/iau/NEO_dev/toconfirm_tabular.html
*** https://www.minorplanetcenter.net/