Development of a Mars dust characterization instrument

The atmosphere of Mars has a considerable load of suspended dust. Over time, this dust deposits out of the atmosphere. The mechanism and the temporal and geographical variation of this deposition are not well characterized. Measurements of settling rates and dust properties are of considerable scientific interest. Suspended dust affects the atmospheric solar absorption and thus the heat balance of Mars, as well as serving as nucleation sites for water and CO2 frost, while settled dust causes albedo changes across the surface; knowledge of dust properties is also of engineering interest to the design of mechanisms, solar arrays, and radiators. Two instruments have been designed and fabricated to measure the dust accumulation during the course of the Mars Pathfinder rover mission: a solar-cell coverglass transmission experiment to measure the change in optical opacity of a transparent coverglass as dust settles on the surface and a quartz crystal monitor to measure the mass of dust deposited on an oscillating quartz crystal as dust settles on the surface. An additional instrument, a CCD microscope to image individual dust particles is under development for flight on a future mission.