Lunar atmosphere and surface analysis through in situ pickup ions

The exploration of the lunar atmosphere and its relation to physical processes that dominate the interaction between the moon its space environment is enabled by the analysis of charged and neutrals from a near-lunar orbit. The Moon has an atmosphere, a collisionless exosphere in which material released from the surface is gravitationally bound. It is very tenuous and very fragile, very much affected and expected to be very much affected by the anticipated lunar exploration program. It is the purpose to this talk to outline the breakthrough science that can be done from a platform in a near-lunar orbit, detecting pickup ions from surface and atmospheric sources. We will discuss expected sources and sinks of these species. We will also focus on transient events from lunar quakes and from meteoritic impacts. Finally, we discuss a possible implementation of an instrument that could do these breakthrough measurements.