  The Apollo 12 lunar module (LM) landing near the Surveyor III spacecraft at
the end of 1969 has remained the primary experimental verification of the
predicted physics of plume ejecta effects from a rocket engine interacting with
the surface of the moon. This was made possible by the return of the Surveyor
III camera housing by the Apollo 12 astronauts, allowing detailed analysis of
the composition of dust deposited by the LM plume. It was soon realized after
the initial analysis of the camera housing that the LM plume tended to remove
more dust than it had deposited. In the present study, coupons from the camera
housing have been reexamined. In addition, plume effects recorded in landing
videos from each Apollo mission have been studied for possible clues. Several
likely scenarios are proposed to explain the Surveyor III dust observations.
These include electrostatic levitation of the dust from the surface of the Moon
as a result of periodic passing of the day-night terminator; dust blown by the
Apollo 12 LM flyby while on its descent trajectory; dust ejected from the lunar
surface due to gas forced into the soil by the Surveyor III rocket nozzle,
based on Darcy's law; and mechanical movement of dust during the Surveyor
landing. Even though an absolute answer may not be possible based on available
data and theory, various computational models are employed to estimate the
feasibility of each of these proposed mechanisms. Scenarios are then discussed
which combine multiple mechanisms to produce results consistent with
observations.
