Physical properties of Near-Earth Objects that inform mitigation

Various methods have been proposed to avoid the collision of a Near-Earth Object (NEO) with the Earth. Each of these methods relies on a mitigation concept (deflection or fragmentation), an energy source (e.g. kinetic, gravitational, solar, thermal, etc.) and a mode of approach (e.g. remote station and interaction). The efficiency of each method depends on the physical properties of the considered NEO that influence the way the body will respond to the considered energy source. While the knowledge of properties such as the mass, spin rate and obliquity as well as the shape is generally required for all mitigation methods, there are other properties that are important to know for some methods and that have no great influence for other ones. This paper summarizes the current knowledge of main physical properties of NEOs and their importance for the most usual mitigation strategies that have been proposed, i.e. the kinetic impactor, the gravity tractor, strategies based on anchoring or depositing material on the surface, and strategies aimed at modifying the thermal properties of the NEO in order to either modify or cancel the Yarkovsky effect, or cause surface vaporization.

► Current knowledge on the physical properties of Near-Earth Objects is briefly exposed.
► Properties that must be known for different kinds of mitigation methods are indicated.
► Role of some properties on the momentum transfer efficiency of a kinetic impactor is discussed.