TheThe LunarLunar DustDust --PlasmaPlasma EnvironmentEnvironment Timothy J. Stubbs 1,2 , William M. Farrell 2, Jasper S. Halekas 3, Michael R. Collier 2, Richard R. Vondrak 2, & Gregory T. Delory 3
[email protected] Lunar X-ray Observatory(LXO)/ Magnetosheath Explorer (MagEX) meeting, Hilton Garden Inn, October 25, 2007. 1 University of Maryland, Baltimore County 2 NASA Goddard Space Flight Center 3 University of California, Berkeley TheThe ApolloApollo AstronautAstronaut ExperienceExperience ofof thethe LunarLunar DustDust --PlasmaPlasma EnvironmentEnvironment “… one of the most aggravating, restricting facets of lunar surface exploration is the dust and its adherence to everything no matter what kind of material, whether it be skin, suit material, metal, no matter what it be and it’s restrictive friction-like action to everything it gets on. ” Eugene Cernan, Commander Apollo 17. EvidenceEvidence forfor DustDust AboveAbove thethe LunarLunar SurfaceSurface Horizon glow from forward scattered sunlight • Dust grains with radius of 5 – 6 m at about 10 to 30 cm from the surface, where electrostatic and gravitational forces balance. • Horizon glow ~10 7 too bright to be explained by micro-meteoroid- generated ejecta [Zook et al., 1995]. Composite image of morning and evening of local western horizon [Criswell, 1973]. DustDust ObservedObserved atat HighHigh AltitudesAltitudes fromfrom OrbitOrbit Schematic of situation consistent with Apollo 17 observations [McCoy, 1976]. Lunar dust at high altitudes (up to ~100 km). 0.1 m-scale dust present Gene Cernan sketches sporadically (~minutes). [McCoy and Criswell, 1974]. InIn --SituSitu EvidenceEvidence forfor DustDust TransportTransport Terminators Berg et al. [1976] Apollo 17 Lunar Ejecta and Meteorites (LEAM) experiment. PossiblePossible DustyDusty HorizonHorizon GlowGlow seenseen byby ClementineClementine StarStar Tracker?Tracker? Above: image of possible horizon glow above the lunar surface.