Annual variation and synodic modulation of the sporadic meteoroid flux to the Moon

Abstract

The Lunar Dust Experiment on board NASA's Lunar Atmosphere and Dust Environment Explorer discovered a permanently present, asymmetric dust cloud engulfing the Moon, sustained by meteoroid bombardment. It is most dense at 5–8 lunar local time, with a peak density canted sunward. Here we present analysis on the variation of the cloud density during January to April 2014. We find the lunar dust cloud in the Moon's equatorial plane to be dominantly produced by impacts from three known sporadic meteoroid sources: apex, helion, and antihelion, listed in order of their contribution to ejecta production. The cloud density is also modulated by the Moon's orbital motion about the Earth, peaking during its waning gibbous phase. These results are complementary to ground‐based measurements and indicate the Moon can be used as a very sensitive large area dust detector to characterize the meteoroid environment at 1 AU.

Constraining the Ratio of Micrometeoroids From Short‐ and Long‐Period Comets at 1 AU From LADEE Observations of the Lunar Dust Cloud

“…We conclude in this work that the meteoroid environment is not the main source of the H/AH imbalance in the LDEX observations reported by Szalay and Horányi (2015). In our model the H and AH sources are approximately equal in terms of the total mass influx on the lunar surface, with small variations during the year due to the Moon's motion.…”

“…Initial results reported by Szalay and Horányi (2015) (hereafter referred as SH15) found that the ejecta cloud in the Moon's equatorial plane is primarily produced by impacts from a combination of the three known sporadic meteoroid sources (Helion, Anti-Helion, and Apex). Initial results reported by Szalay and Horányi (2015) (hereafter referred as SH15) found that the ejecta cloud in the Moon's equatorial plane is primarily produced by impacts from a combination of the three known sporadic meteoroid sources (Helion, Anti-Helion, and Apex).…”

“…(c) Predicted Helion-to-Anti-Helion flux ratio impinging on the Moon's surface for both orbitally biased and unbiased results and the fitted results reported bySzalay and Horányi (2015) as derived from LDEX measurements. (b) Normalized M + predicted to be observed by LDEX given the satellite's orbital characteristics.…”

Impact Ejecta and Gardening in the Lunar Polar Regions

“…In this study, we expand that fit to include the high‐latitude NT/ST sources (Pokorný et al, ). Each source is modeled as a collimated beam from a specific radiant direction, and the subsequent impact ejecta response is assumed to follow where m is the characteristic mass of the impactors, F m is the mass flux, v is the impactor speed, α = 0.23 and β = 2.46 are experimentally determined constants, and φ is the angle of impact ejecta relative to the surface normal (Gault et al, ; Koschny & Grün, ; Szalay & Horányi, ). Equation is given as a proportionality relation since M + is scaled to the actual lunar values derived by LDEX measurements, described below.…”

Radiation Effects on Airless Bodies in Space: Radiolysis, Sputtering, and Sintering in Regoliths

“…The production of detectable of amounts material by impacts has been verified around the Moon in LADEE neutral mass spectra where periodic spikes in the exosphere density correlate with known orbital crossing meteorite streams [Szalay and Horányi, 2015]. While dust impacts may generate detectable amounts of ejecta, they are neglected in this analysis since the calculations have already been carried elsewhere out for the martian moons [Cipriani et al, 2011].…”