Overview of Mars system-environment interactions

Planetary surfaces present a unique set of environmental conditions with which surface infrastructures must interact. These interactions must be understood if vehicles are to operate successfully. This paper presents an historical survey of studies and laboratory work done for the Space Exploration Initiative, and the Pathfinder Rover. Topics covered are vehicle electrostatic charging and environmental interactions with a special focus on Paschen breakdown. A final argument is made for the necessity of thoroughly understanding planetary surface infrastructure environmental interactions in general. Labora tory tests, and new vehicle-environmental interactions models and guidelines for planetary surface operations, similar to those Copyright * 1996 by AIAA, Inc. No copyright is asserted in the United States under Title 17, U.S. Code. The U.S. Government has a royaltyfree license to exercise all rights under the copyright claimed herein for Government purposes. All other rights are reserved by the copyright owner. already developed (or being developed) for earth orbit are advocated. 1. ELECTRICAL AND CHEMICAL INTERACTION ON MARS WORKSHOP (NOVEMBER, 1991) On 19-20 November 1991, a workshop (Ref. 1} was held at NASA Lewis Research Center to identify issues related to electrical and chemical interactions between systems and their local environments at Mars, and to recommend means of addressing those issues, including sending robotic spacecraft to Mars to acquire necessary information. The workshop began with a series of presentations on Mars surface and orbital environments, SEI systems, environmental interactions, modeling and analysis, and plans for future exploration. After the talks, participants were divided into two working groups, one to examine the martian surface, the other, Mars orbit. The working groups were asked to identify issues in the form of environmental interactions, to state what is known for each issue, what new knowledge is needed, and to recommend ways of filling the need. issues were prioritized within each working group using relative severity of effects as a criterion. The workshop was carried on under the auspices of the Environmental Interactions Working Group, chaired by J. Kolecki and G. Hillard of NASA Lewis Research Center. It was part of a larger organization, assembled within NASA, to develop robotic mission program requirements for the Space Exploration Initiative (SEI). The objective of the Environmental Interactions Working Group was to identify environmental interactions issues, and formulate and document robotic precursor mission requirements based on these issues. Typical issues addressed during the workshop included Paschen electrical breakdown in the low pressure martian atmosphere (see section 3, below); charged or polarized sand and dust (see section 2); electrical discharges accompanying ascent/descent engine firing; atomic oxygen and C02 in low Mars orbit (LMO); Mars plasma environment; Mars' orbital dust, meteoroid, and debris environment; radiation at the martian surface and in LMO; and plasma generation during aerobraking. The working groups reached conclusions which are summarized here: