Effects of the lunar environment on space vehicle surfaces

On the lunar surface there exists very localized and weak magnetic fields, leaving its surface essentially directly exposed to the impact of solar UV and X-rays as well as solar wind plasma and energetic particles. The lack of atmosphere results in a lunar environment charging positive in sunlight and negative in shadow regions resulting in potentials that can vary over orders of magnitude in response to changing solar illumination and plasma conditions. At the macro-scale, contaminant adhesion due to van der Waals´ forces are very small and can be easily perturbed by other external forces. However, at the nano-scale, van der Waals forces can be significant. Lunar regolith or dust contamination is a serious problem for equipment and vehicles for space mission applications. Dust contamination gathers on photonic sensors inhibiting motion and data gathering. In addition, devices that require transparency to light for maximum efficiency such as solar photovoltaic power systems, video cameras and optical or infrared detectors will suffer from the dust accumulation. The electrostatic charging of the lunar surface is caused by its interaction with the local plasma environment and solar UV and X-rays induced photoemission of electrons. The lunar thermal environment poses unique challenges to vehicle and sensor surfaces since it is characterized by large temperature variations, long hot and cold soak times, and reduced heat rejection capability due to the presence of the lunar regolith. Fundamental forces (van der Waals) that allow certain contamination to adhere to critical surfaces and methods are being tailored to make these surfaces suitable for this harsh environment.