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[14.14] Electrostatic Discharging of Dust near the Surface of Mars

C.E. Krauss, M. Horanyi (LASP, Univ. of CO), S. Robertson (Dept. of Physics, Univ. of CO)

Due to the prevalence of Martian dust devils and dust storms, an understanding of the underlying physics of electrical discharges in Martian dust is critical to future Mars exploratory missions. When dust particles come into contact, charge can be transferred between the grains. Wind driven dust studies (Stow, 1969) show that in the case of particles with identical compositions, the particle with the larger radius in a collision preferentially becomes positively charged. Upwinds within a dust cloud can carry the lighter, negatively-charged particles to higher altitudes. The stratification of particle sizes causes an electric dipole to form. When the electric potential within the cloud exceeds the breakdown voltage of the surrounding atmosphere, a discharge occurs.

We have created a simple theoretical model to examine the creation of discharges in a Martian dust storm. The effects of pressure, dust density, and particle size are presented. These model results are compared to our laboratory experiments which examine the creation of discharges due to vertical charge separation in a simulated Martian environment. When JSC-Mars-1, a Martian regolith simulant, is vertically dropped in a low-pressure CO₂ atmosphere, electrical discharges are both visually and electronically detected. Measurements of the frequency and intensity of these discharges show that they can occur under conditions expected on the Martian surface.

This work is supported by NASA Space Science GSRP, NGT5-50345.

The author(s) of this abstract have provided an email address for comments about the abstract: kraussc@colorado.edu

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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.