Near-Earth Asteroids (NEA) are a population of asteroids with Earth-crossing orbits generally having perihelion distances q ≤ 1.3 A.U. and aphelion distances Q ≥ 0.983 A.U. Among this population there is a sub-class of Potentially Hazardous Asteroids (PHA) represented by objects with an absolute magnitude H ≤ 22 (corresponding to a diameter of 1 km or larger) having a Minimum Orbit Intersection Distance (MOID) of 0.05 A.U. or less.
Dynamical calculations show that the typical lifetime of NEA is much shorter than the age of the Solar System. They are constantly removed from the inner region of the Solar System in few million years ending their lives by falling onto the Sun, by impacting the terrestrial planets, or by acquiring high eccentricity, ejection orbits. These short lifetimes require stable sources to resupply the NEAs. Finding these sources and the associated mechanisms for resupplying the NEAs population is a key problem of the planetary science. Investigation of the important link between these sources and NEAs requires combined knowledge of their dynamical and physical properties and evolution. The interest in studying NEAs is mostly driven by the significant risk they pose to Earth during the threatening close approaches. With more than 1300 NEAs classified as PHA, the danger of a catastrophic impact in a foreseeable future is non-negligible.
The need to fully characterize this population of potentially Earth impactors leads to a second motivation of their study: NEAs can provide critical data, otherwise inaccessible, needed to reconstruct the formation and the early stages of the Solar System. Their proximity and small dimensions make NEA relatively accessible to space-craft investigations. Several programs for space exploration of these objects (Marco Polo-R, OSIRIS-REx, Hayabusa2) are now under study around the world. The choice of targets and the planning of space exploration are based on strong ground-based science. Thus, the knowledge of the ensemble of physical and dynamical parameters of objects and their composition is a critical point in defining the mission scientific objectives.
Our program COD-NEA - Compositional and dynamical modeling of near-Earth asteroids aims to characterize the compositional and physical properties of some of the most important NEAs using multi-wavelength (visible, infrared), multi-instruments (photometer, spectrometers) techniques and to explore their dynamical evolution by means of massive, parallel numerical integrations. The project is based on the previous experience of the project's team in the field of planetary sciences and on two existing facilities: the Remote Observation Center in Planetary Sciences (ROC) and the SGI ALTIX 3700 supercomputing system both currently hosted and operated by the Astronomical Institute of the Romanian Academy (AIRA).
Aiming to obtain critical physical and compositional information needed to assess the damage potential and impact risk of NEAs this program is situated within the objectives of the European Space Agency (ESA) Space Situational Awareness (SSA) initiative. The expected results of the project should strengthen the integration of the Romanian planetology community into ESA scientific programs such as MarcoPolo-R space mission.