Detecting electrical activity from Martian dust storms

Abstract

Abstract. We present a model addressing the possible electrification of Martian dust storms based on the effective electrical charging of an individual dust grain. An upper charge bound on a grain can be determined based on the grain capacitance in the lowpressure Martian atmosphere. It is assumed that treiboelectric and inductive processes, like that presumed operating in terrestrial dust storms, can electrify the grain to significant levels. A collection of such grains charged in a dust cloud of many tens of kilometers in size can yield a substantial electric field moment. Given various grain charge and dust storm sizes, the electric moment will be determined along with estimates of electrical discharge and emitted radio power based upon known models. We also suggest the possibility that remote detection of discharge-related VLF emission propagating in the surface/ionosphere waveguide can be used to determine subsurface conductivity. However, to date, there has been no report of orbiter or lander optical images of lightning-like discharges. Further, there is no report of lightning-induced interference on radio 3795

Electric and magnetic signatures of dust devils from the 2000–2001 MATADOR desert tests

“…The observation suggests that the cyclonic fluid motion creates a large-scale magnetic dipole moment, m, associated with the circular solenoid current, m = IA, where I is the total current carried by the grains and A is the dust devil cross-sectional area. This large-scale ULF magnetic moment complements the already known large-scale electric dipole moment of a dust devil [Freier, 1960;Crozier, 1964;Farrell et al, 1999].…”

“…While the measured E-fields are 0.1% of terrestrial atmospheric breakdown, they are in fact about 10 -20% of the Martian breakdown potential (of $20kV/m [Farrell et al, 1999]). Consequently, a similar charge generation process from a comparable dust devil on Mars would result in electrostatic field values approaching breakdown, again as simulated by Melnik and Figure 4.…”

“…As heavy grains descend, the lighter (-) grains remain suspended creating a large inter-devil potential on the order of hundreds of kilovolts, with associated electric fields reaching the Martian atmospheric breakdown potential of 20 kV/m. Because of mass stratification of the charged dust, the dust cloud then obtained a macroscopic electric dipole moment (M = 2Qh, Q being the charge of each pole and h the cloud height) oriented in the nadir (downward) direction [Farrell et al, 1999]. This simulation was one of the first efforts that explained the large-scale electric field development as resulting from combined fluid forces/mass stratification and a mass-preferential grain charging process.…”

“…The moment-related electricity can be sensed in three different ways: First, the large scale electric field associated with the dust devil can be detected by quasi-DC E-field sensing systems such as field mills [Freier, 1960;Crozier, 1964]. Second, any change to that moment at either the macroscopic or microscopic level represents a dM/dt that gives rise to radiation [Farrell et al, 1999] that can be detected as radio waves. The exact frequency of radiation depends upon the scale size and temporal nature of the currents [Farrell et al, 1999].…”

“…Second, any change to that moment at either the macroscopic or microscopic level represents a dM/dt that gives rise to radiation [Farrell et al, 1999] that can be detected as radio waves. The exact frequency of radiation depends upon the scale size and temporal nature of the currents [Farrell et al, 1999]. Finally, the charged dust devil should induce potentials on objects that are immersed in the dust storm.…”