The Martian environment is a diverse environment with which systems will interact in numerous ways. Preliminary thoughts on electrical system/environment interactions which might be of interest to system designers at all stages of system design are presented. These interactions are primarily related to electrical charging, contamination, and Martian surface sand and dust

Ferguson, D. C.

Hillard, G. B.

Kolecki, J. C.

English

NASA Technical Reports Server

N91-27068
ELECTRICAL SYSTEM/ENVIRONMENT INTERACTIONS ON THE
PLANET MARS J.C. Kolecki, G.B. Hillard, and D.C. Ferguson, Space
Environment Interactions Br., NASA Lewis Research Center, NASA 2100 Brookpark Road,
Cleveland, OH 44135
The Martian environment is a diverse environment with which systems will interact
in numerous ways. The following comments are preliminary thoughts on electrical
system/environment interactions which might be of interest to system designers at all stages
of system design.
Stationary surface sand and dust may be subject to electrical charging due to incident
solar ultraviolet light which reaches the Martian surface at an intensity approximately equal
to its value in Mars space. Additionally, sand and dust charging could also occur around
electrically powered systems by induced dipole coupling effects with exposed high voltage
surfaces. When such charging occurs, regardless of the mechanism involved, Coulombic
forces result in the sand and dust being attracted and adhering to surfaces, thereby
modifying surface thermal, optical, and dielectric properties. Stationary surfaces will acquire
variable coatings of sand and dust which must be dealt with both in system design, and later,
in situ on the Martian surface. Further, sand and dust transported on roving vehicles,
and/or human explorers moving out of and into controlled volumes could pose a significant
contamination problem.
Wind borne dust may also be subject to electrical charging due to triboelectric
mechanisms. Differential settling of triboelectrically charged dust following major dust
storms may result in significant charge seperation with concomitant electrical breakdowns
between surfaces, or to the Martian ground or atmosphere. Additionally, the presence of
variable levels of sand and dust in the Martian atmosphere may significantly modify
atmospheric electrical properties as seen by systems on the Martian surface. As a gas, the
7 - 9 Torr surface atmosphere is ideal for Paschen electrical breakdown over mm to cm
distances at a few hundred volts, and cm to m distances at a few kilovolts. Atmospheric
dust will certainly modify the breakdown properties of the atmosphere, acting possibly to
seed or suppress breakdown phenomena around high voltage surfaces depending on such
factors as atmospheric dust concentration, dust surface adhesion (or lack thereof), and dust
dielectric properties. Paschen breakdown phenomena have been observed on Earth in
simulated Martian conditions, and are known to result in system power loss and
electromagnetic noise. Transient and sustained electrical discharges in general may sputter
erode surfaces and result in contamination due to transport and redeposition of material.
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The questionwhich is of mostinteresthere is: What happenswhenyou add a system
to an environment and "shakewell?" How doesone characterizethe resulting interaction
and use that knowledge to produce optimal system designs? Some areas for
consideration/development include:
1.)
2.)
3.)
4.)
5.)
6.)
Identifying relevant physical mechanisms/equations
Producing, and (where necessary) experimentally verifying mathematical
models
Understanding user needs and establishing appropriate user interfaces
Establishing appropriate input/output formats
Identifying/performing relevant laboratory/space tests and analyses
Delivering user-friendly software with appropriate interfaces
The Space Environment Effects Branch has worked for almost two decades on the
development of analysis tools and computer software for use in designing systems for the
LEO and GEO plasma environments. This software includes NASCAP/LEO and
NASCAP/GEO (NASCAP = NASA Charging Analysis Program), which model system-
plasma interactions including spacecraft charging, arcs and transient phenomena, anomalous
switching, spacecraft grounding effects, and numerous related issues. Other software
packages (EPSAT, and SSF ENVIRONMENT WORKBENCH) are also under development
which will provide frameworks into which specific environment and system models may
inserted, and interactions predicted. The charter of the Space Environment Effects Branch
is to develop and provide modeling and analysis tools for the interactions between given
environments and given systems, and to conduct whatever experimental and/or flight
activities are necessary to validate those tools. With the advent of the Space Exploration
Initiative, it seems appropriate that interactions models be developed for the moon and
Mars. These models will provide systems engineers with unique, user-friendly tools which
will couple the environmental models currently under development with systems models
either extant or yet to be developed, and to predict the interplay of the two from an
electrical/plasma interactions point of view. This capability will enable the best possible use
of the environmental models for the moon and Mars in the production of optimal system
designs.
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Electrical system/environment interactions on the planet Mars

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