“How can OSIRIS-REx help us prevent a future asteroid impact from Bennu or another asteroid?”

The Yarkovsky Effect is non-gravitational force which arises when an asteroid receives energy from the sun, absorbs it to heat up the surface, and then re-emits it back into space later in its solar day. This anisotropic emission of thermal radiation imparts a small force on the asteroid that substantially changes its semi-major axis. We will get a much more accurate measurement by tracking the spacecraft in the vicinity of Bennu. In addition, using our thermal emission spectrometer, we will get spatially resolved information on the total amount of radiation emitted from the asteroid surface as a function of the time of day. This information will allow us to test the theory of the Yarkovsky effect and improve our knowledge of the fundamental asteroid properties that give rise to this phenomenon. We can not get such detailed and high-quality information from ground-based telescopic observations.