TITLE: The Space Plasma – Human Object Interactions at Airless Bodies
PRESENTER: William M. Farrell
NASA/Goddard Space Flight Center
SSERVI/DREAM2 Center for Space Environments
Co-authors: Amy Ross, NASA/Johnson
Space is not a vacuum: It is a conductive medium consisting of ions and electrons outflowing in the solar wind plasma. Airless bodies like the Earth’s Moon, Mars’ Phobos, and near-Earth asteroids represent obstacles in this plasma outflow, possessing trailing low density wake structures and voids in the plasma at local obstructions (mountains, craters) along the terminator – hence making the near-surface plasma environment very complicated and dynamic. Human systems represent a third element introduced into the environment, and these human systems can become charged as they rove over the regolith-rich surface. However, the nature of the dissipation of the collected charge depends greatly upon the local plasma environment – which represents a dissipation path or the ‘electrical ground’. In this presentation, we review spacecraft charging in plasma environments, but now consider a dynamic aspect for objects roving on regolith-rich bodies. We find that human systems can charge up on surfaces immersed in low density plasmas– and we explain how this can happen and provide recommendations for remediating the charge buildup. We especially tailor the discussion in the context of space suits and rover wheels that would charge on these regolith-rich surfaces.
Dr. Bill Farrell is a plasma physicist in the Solar System Exploration Division at NASA/Goddard Space Flight Center. He received his Ph. D. from the University of Iowa in 1987, and has been a NASA Goddard civil servant since 1990. His research interest include the study of lightning storms at Earth and the planets, the dusty plasma environment at planetary moons and asteroids, the space environment at our own Moon, and atmospheric breakdown in Mars dust storms. He is a co-investigator on the Cassini mission to Saturn, the Solar Probe Plus mission, and Wind spacecraft. He is also currently a Principal Investigator of the DREAM center for lunar science that examines the space weather and plasma interaction at the Moon. His instrument team has built over 10 radio/plasma wave elements to fly on rockets, balloons, in remotely piloted vehicles, and for space flight. Dr. Farrell continues to be a scientific reviewer on AGU, EGS, and IEEE journals and he regularly sits on Mars and Moon science definition and review teams. He has published over 180 articles in space sciences.