Program of the Colorado Center for Lunar Dust and Atmospheric Sciences

The Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) is a member of the NASA Lunar Science Institute, focused on experimental and theoretical investigations of the lunar surface, including dusty plasma and impact processes, the origins of the lunar atmosphere, and the development of new instrument concepts, with a complementary program of education and community development. The tenuous lunar atmosphere is a surface-bound exosphere (SBE) similar to that found throughout the solar system, for example on Mercury, various icy satellites, over the rings of Saturn, on large asteroids, and on Kuiper Belt objects. Its time-dependent constituents arise from a dynamic balance between sources that may be sporadic (solar wind, sputtering, micrometeoroid impacts, outgassing) and loss mechanisms (escape, ionization), creating a natural dusty plasma laboratory. The characterization and formation mechanisms of the lunar exosphere, in particular the role of constant micrometeoroid bombardment of the lunar surface, have been the subject of debate since the Apollo era. CCLDAS is conducting a series of laboratory experiments supplemented by state-of-the-art theory and modeling, to determine: (1) The properties of a carefully-simulated near-surface plasma environment, and the intense localized electric fields expected to develop due to differential charging near the terminator regions and in localized shadows; (2) The charging of grains resting on dusty surfaces and stirred by activities, their possible mobilization, lift-off, transport and adhesion; 3) The microphysics of impact phenomena from hypervelocity micrometeoroids and their interaction with simulated lunar environment. In addition to the experimental facilities featuring intense UV and simulated solar wind sources, a major component of the experimental program is a dust accelerator for micron-sized grains, to closely reproduce the effects of micrometeoroid impacts onto the lunar surface. Diagnostic considerations include the ability to measure the energy distribution, angular distribution, and composition of both vapor and particulate debris removed by impacts. Experiments will also be conducted at the NASA Johnson Space Center Vertical and Light Gas Gun Facilities in order to extend the mass and velocity range of the impacting particles.