P23C-4003:
Influence of Meteoroid Streams on the Lunar Environment: Results from LADEE
Tuesday, 16 December 2014
Timothy John Stubbs1, David A Glenar2, Yongli Wang3, Menelaos Sarantos4, Brendan Hermalyn5, Anthony Colaprete6, Diane H Wooden6, Mehdi Benna7 and Richard C Elphic6, (1)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (2)University of Maryland Baltimore County, CRESST, Baltimore, MD, United States, (3)NASA/GSFC, Greenbelt, MD, United States, (4)University of Maryland Baltimore County, Baltimore, MD, United States, (5)University of Hawaii at Manoa, Honolulu, HI, United States, (6)NASA Ames Research Center, Moffett Field, CA, United States, (7)NASA - GSFC, Greenbelt, MD, United States
Abstract:
Impacts on the lunar surface from meteoroid streams encountered by the Earth-Moon system can result in measurable enhancements in both the lunar atmosphere and dust environment. Here we describe the annual meteoroid streams incident at the Moon during the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission, and discuss their effects on the lunar environment. The LADEE science payload consisted of three instruments: the Ultraviolet/Visible Spectrometer (UVS); the Lunar Dust Experiment (LDEX); and the Neutral Mass Spectrometer (NMS). All three instruments detected the effects of encounters with meteoroid streams. During its time in lunar orbit, the LADEE mission coincided with 18 out of 35 IAU established annual streams. As stream meteoroids move on near-parallel trajectories we expect to observe asymmetries in their effects on the lunar environment. Based on predicted incident meteoroid mass fluxes at the Moon, one might expect the Geminids and Quadrantids to have had the most significant effect on the lunar environment during the mission. While a substantial exospheric response was clearly observed by the LADEE instruments during the Geminids, the apparent response during the Quadrantids was more subdued. One contribution to this difference was likely due to the location of the stream radiant on the lunar surface relative to LADEE’s orbit. The Geminids radiant was predicted to be very close to LADEE’s equatorial orbit, whereas the Quadrantids radiant was much farther poleward. This could explain the diminished exospheric activity and suggests that the response of the lunar environment to meteoroid streams could be relatively localized in some instances. Both short-term and long-term variations observed in the lunar sodium exosphere could be attributed to the instantaneous and cumulative effects of meteoroid stream bombardment. These and other effects will be discussed.
