Dynamics, orbit determination, and impact monitoring of near-Earth asteroids
Dynamics, orbit determination, and impact monitoring of near-Earth asteroids
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The main topic of my research is the dynamics of near-Earth asteroids (NEAs). During the Stardust-reloaded project I focused on the long-term dynamics of NEAs. I developed a model for the computation of proper elements of NEAs in a mean-motion resonance, and I used proper elements to locate secular resonances in the near-Earth region. Proper elements can be used also to find associations between NEAs and meteorites.
I also developed a modified version of the orbit9 and mercury N-body codes, including the combined action of the Yarkovsky and YORP effects, that can be used for statistical studies on the dynamics of small asteroids.
My current work at the ESA NEO Coordination Centre is focused on orbit determination and impact monitoring of NEAs. My main duty is to maintain the orbit catalogue of NEAs and to assess the impact threat of NEAs with the Earth. I developed a new algorithm for the automated detection of the Yarkovsky effect on NEAs, which is now an operational tool of the NEOCC. I also contribute in the development and operations of the Aegis Orbit Determination and Impact Monitoring software and the Meerkat Asteroid Guard for imminent impactors alerts.
Physical properties of near-Earth asteroids
Physical properties of near-Earth asteroids
During my postdoc I developed a statistical method to study the thermal properties of the super-fast rotator (499998) 2011PT, which is based on the comparison between the measured and the model-predicted Yarkovsky effect. Results showed a surprisingly low thermal inertia (see Figure 1), lower than that of Bennu and Ryugu, with a very high probability.
The D-NEAs project, which is based on the preliminary work on 2011 PT, was aimed at further developing new methods for the physical characterization of near-Earth asteroids, that rely mostly on ground-based observations. Within this project, we presented our publicly available software ASTERIA, that we used to estimate the thermal inertia of several sub-km NEAs, including asteroid Didymos.
The D-NEAs project was carried on by myself, Bojan Novaković, and Dušan Marčeta from the Astronomy Department of the University of Belgrade. The project was awarded with the Planetary Society STEP grant 2021.
Probability density function of the thermal conductivity (top panel) and of the thermal inertia (bottom panel) of the super-fast rotator (499998) 2011PT.
Asteroid (469219) Kamo'oalewa
Asteroid (469219) Kamo'oalewa
Asteroid (469219) Kamo`oalewa is the target of the Tianwen-2 mission by the Cinese National Space Administration (CNSA), and I studied different aspects of this asteroid. With numerical simulations, I showed that the Yarkovsky effect can influence the residence time of Kamo`oalewa in the Earth co-orbital region, which will still remain a companion of the Earth for the next 0.5 Myr.
In early 2025 we followed-up Kamo`oalewa from the Loiano Observatory in Italy, and from the Calar Alto Observatory in Spain. We also accurately remeasured the pre-coveries from 2004 by SDSS, and thanks to this we were able to determine the Yarkovsky effect with a good signal-to-noise ratio of 14. We then could apply the ASTERIA method to estimate the thermal inertia of Kamo`oalewa, and we found that this asteroid is a small super-fast rotatior with low thermal inertia, similar to 2011 PT. Thermal inertia is particularly important for sample-return missions, since it provides information on possible material on the surface of the asteroid.
Asteroid (469219) Kamo`oalewa as imaged by the Tianwen-2 spacecraft. Credits: CNSA.
With numerical simulations, we also investigated whether Kamo`oalewa is more likely to originate from the main asteroid belt or from the Giordano Bruno crater on the Moon. Our results show that the main asteroid belt is able to produce ~1 Kamo`oalewa-like Earth quasi-satellite on average, while the Giordano Bruno crater could produce only 0.042. Thus, the origin from the main belt is favoured by current models.
I also participated to several other pre-arrival studies, including shape modeling, space weathering effects, and composition. Predictions made by ground-based observations will finally be corroborated by in-situ observations obtained by the Tianwen-2 spacecraft.
Origin of meteorites and meteoroid dynamics
Origin of meteorites and meteoroid dynamics
Together with Albino Carbognani from the Italian Istituto Nazionale di Astrofisica (INAF) we studied the possible origin of meteorites directly from the NEA population.
By using numerical simulations, we found 12 meteorites that are possibly linked to known NEAs, which may have been originated through a small collision on the proposed parent body.
Further clues that some meteorites may originate directly in the near-Earth space from micro-meteoroids collisions on small NEAs are given by the results of the impact of the DART spacecraft on Dimorphos. In fact, meter-size boulders ejected from Dimorphos were imaged by the Hubble Space Telescope. We simulated the long-term dynamics of these boulders, and found that they could eventually reach the surface of Mars. The same mechanism applies to NEAs that cross the orbit of Earth.
Meteorites are also of great value for planetary science research, and it is important to recover them from the ground. An important source of meteorites are small asteroids that are discovered by telescopic images few hours before impact, the so called imminent impactors. We demonstrated that strewn fields computed from heliocentric orbital data are still a valuable resource for meteorite search on the ground.
Orbits of meteorites with known pre-impact heliocentric orbit (in pink), together with the orbits of the planets from Mercury to Jupiter. Blue dots are an artistic representation of the asteroid main belt.
Periodic orbits of the N-body problem (PhD Project)
Periodic orbits of the N-body problem (PhD Project)
During my Ph.D period I studied the existence of periodic orbits of the N-body problem with equal masses, using variational and numerical methods. Variational methods permit to prove the existence of periodic orbits with special symmetries, while numerical methods permit to actually compute such orbits and study additional properties, such as their stability.
First, I applied rigorous numerical techniques to produce a computer-assisted proof of the instability of particular periodic solutions of the N-body problem with equal masses, and some computations can be found here.
During my staying in Barcelona, I used numerical methods to compute symmetric periodic orbits in the Coulomb (1+N)-body problem, that is strictly related to the gravitational N-body problem. The computations performed for this paper can be found here.
Later, I used variational techniques to prove the existence of periodic orbits of the (1+N)-body problem, and used the Gamma-convergence theory to study their asymptotic properties. Additional computations of this work can be found here.
I used numerical method to compute the bifurcations of the collinear configuration of the 3-body problem viewed as a balanced configuration. Additional material of this paper can be found here.
A periodic orbit of the N-body problem for N = 60, with the symmetry of the Icosahedron.
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