Abstract
This paper reviews studies on dust motion above the surface of asteroids. Photoelectron emission effect makes asteroidal surface charged-up positively resulting in a thin electron sheath above the surface. At the same time, a dust grain on or above the surface is also charged-up positively or negatively due to the balance between photoelectron emission and injection of solar wind and electron sheath electron. Thus motion of dusts above the surface is affected not only by gravitational acceleration but also electric force from the electric field above the surface. Under some special condition, a dust levitates above surface for a longtime, which might result in characteristic morphology such as “pond” on Eros. If dust size is smaller than a threshold value, the dust can escape from the gravity of the asteroid due to electric repulsion. Such an electric escape can be one of source mechanisms of interplanetary dust grains.
