Scientific Requirements for Understanding the Near-Earth Asteroid Population

Abstract

A vital prerequisite for the development of an effective mitigation strategy for hazardous near-Earth asteroids (NEAs) is a thorough understanding of their physical nature and mineralogical composition. The deflection of an object on collision course with the Earth would require the use of considerable force, the successful application of which would depend on prior knowledge of parameters such as mass, shape, strentgh, structure, and rotational characteristics. Recent experience has shown that much can be learned about individual objects from fly-by and rendezvous missions and such missions would play the dominant role in gathering mitigation-relevant information once a dangerous potential impactor had been identified, provided sufficient time were available before the impact. In the meantime, it is important to study the NEA population in general to enable the most likely physical characteristics of a potential future impactor to be anticipated as accurately as possible. Groundbased, airborne, and satellite observatories offer a wide range of techniques with which large numbers of near-Earth asteroids can be remotely sensed, including optical photometry, thermal-infrared spectroscopy, and radar. The merits of techniques most useful from the point of view of NEA hazard assessment and mitigation, and the type of information each can provide, are discussed. The interdependency of the interpretation of data from the various observing techniques is emphasized.