Asteroids are Solar System bodies orbiting the Sun inside the orbit of Jupiter. Asteroids do not show signs of cometary activity, and they are not massive enough to be called "planets".
Asteroids are leftover debris from planetary formation. Therefore, their compositions and dynamics are rich in information about the formation and evolution processes of the Solar System.
Besides my activities of asteroid observations, I study the dynamics of asteroids, in particular those called "Near-Earth asteroids".
The orbits of most asteroids are unstable over long periods of time. In mathematical terms, this means that there exist no constant quantities (called "first integrals") determining their trajectories in a unique way.
Yet, instabilities in asteroid orbits unfold over very long timescales. Over short timescales (of the order of a thousand years), it is therefore possible to express their trajectories using quantities that are "almost" conserved, that is, that vary very slowly over time. These quantities are called "proper elements".
Proper elements are very useful to identify asteroid "families", coming from the fragmentation of a given parent body after a collision.
As part of a project led by Marco Fenucci and Giovanni Gronchi (Italy), we have developed a new method to compute asteroid proper elements, that can be applied even if the asteroid is in resonance with a planet and crosses the orbit of another planet [xviii].
These results will allow us to identify very young families of Near-Earth asteroids. They will also tell us about the dynamics pathways through which asteroids can be transferred from the Main Belt (between Mars and Jupiter) to the orbit of the Earth, where they can pose a threat.
The dynamical pathways highlighted for asteroids are also responsible for the scattering of cometary dust grains, called "meteoroids". When the Earth passes through a meteoroid stream, we experience a meteor shower.
As part of a project led by Ariane Courtot, we have identified the resonances through which two meteoroid streams are scattered or confined: the Draconids and the Leonids [xxii].
Because of the high eccentricity and high orbital inclination of meteoroids, their resonances with planets are complex and require the development of dedicated semi-analytical tools.
Last update: 2024-11