Work Package 5

THE CRITICALITY OF SMALL ASTEROIDS

State of the Art

Our observational knowledge of the asteroid populations is far from being complete. Therefore, asteroid population models are the main source of information about the number of objects in the size-range below a certain threshold. The main belt and NEAs do not represent independent populations, as they are closely connected by evolutionary processes and dynamical transport mechanisms associated to orbital resonances. Recent modeling of the steady state orbital distributions of NEAs extends up to H = 25 mag, i.e. down to a few tens of meters. Despite its great success, this model may still have some shortcomings. As pointed out in, the main belt escape rate does not match very well the observed flux of NEAs. Moreover, for a very small objects it may not be fully appropriate, as it assumes the same orbit distribution for large and small objects in the main belt that may not be necessarily true because for the very small sizes non-gravitational forces become comparatively more important. In order to have the orbital distributions of small NEAs, first the orbit and size distribution of these objects in the main belt is required. However, both distributions are currently poorly known, if known at all. Some available estimations are based only on indirect evidence, such as disruption rate of small main belt asteroids. Last but not least, the asteroid belt is subject to evolutionary processes. So far, no model has included all the important processes affecting asteroid evolution. Besides, new models still have to be successfully tested against known constraints.

Objectives

WP5 extends the distribution of near Earth objects to include asteroids of small dimensions down to few tens of meters and covering regions still poorly known. WP5 defines a criticality index that provides a measure of how easy the asteroid is to deflect with a given deflection method, and how interesting the asteroid is to explore and to exploit.

Research Output

Fenucci, M., Novaković, B., Vokrouhlický, D., &Weryk, R. J. (2020). The low thermal conductivity of the super-fast rotator(499998) 2011 PT. Astronomy and Astrophysics, https://doi.org/10.1051/0004-6361/202039628.

Fenucci, Marco; Gronchi, Giovanni F., Symmetric constellations of satellites moving around a central body of large mass, http://arxiv.org/abs/2003.04580.

Fenucci, M., Novaković, B. (2021). The role of the Yarkovsky effect in the long-term dynamics of asteroid (469219) Kamo’oalewa. Submitted.

Fenucci, M., Novaković, B., Vokrouhlický, D., Weryk, R. J. (2021). Unexpected Thermal Properties of the Near-Earth Object (499998) 2011 PT. Oral presentation at the Lunar and Planetary Science Conference 52, Accepted for Virtual Conference, 15 – 19 March 2021.

Fenucci, M., Novaković, B., Vokrouhlický, D., Weryk, R. J. (2021). The low thermal conductivity of the super-fast rotator (499998) 2011 PT. Accepted for oral presentation at the 7th IAA PDC Conference 2021, 26 – 30 April 2021.