ARTEMIS Observations of Solar Wind Proton Scattering off the Lunar Surface

Lue, Charles; Halekas, J. S.; Poppe, A. R.; McFadden, J. P.

doi:10.1029/2018ja025486

Cited by 23 publications

(26 citation statements)

References 43 publications

(92 reference statements)

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“…A typical value of the compressibility of the SW fluctuations is about 0.03 and does not depend on the frequency through the inertial range (Šafránková et al, 2019). We assume that the enhanced compressibility can be caused by the modification of the SW wave field by a presence of ions reflected from the lunar surface (Harada et al, 2015;Lue et al, 2018). Surprisingly, a larger portion of compressive fluctuations is observed at the lower frequency (0.005 Hz, left panels).…”

Section: Discussionmentioning

confidence: 92%

“…Taken into account the way of the data selection and overall geometry, these distances correspond to measurements at the Moon dayside during periods of nearly radial IMF. We assume that the enhanced compressibility can be caused by the modification of the SW wave field by a presence of ions reflected from the lunar surface (Harada et al, 2015;Lue et al, 2018). It means that the mechanisms of the wave particle interaction would be similar to that in the FS.…”

Section: Discussionmentioning

confidence: 99%

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Solar Wind Proton Deceleration in Front of the Terrestrial Bow Shock

et al. 2019

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The terrestrial foreshock as a region permeated by different types of plasma waves, various particle populations, and strong wave activity is a subject of intensive investigations. Our statistical study of the solar wind proton velocity deceleration in the foreshock uses multipoint observations of the THEMIS mission and compare them with the Wind solar wind monitor with a motivation to estimate the factors influencing evolution/modification of the solar wind speed. In order to follow changes of the solar wind proton speed, our moment calculations do not include the reflected particles as well as heavier ions. We have found a systematic deceleration of the solar wind protons with a decreasing distance to the bow shock that is correlated with the flux of reflected and accelerated particles, with the level of magnetic field fluctuations in the ultralow frequency range, and with their compressibility. We can conclude that the reflected particles excite waves of large amplitudes and, as a consequence, modify median values of the velocity measured in an unperturbed solar wind. The deceleration is as high as 3% in front of the quasi‐parallel bow shock and decreases with the distance being observable up to 50 RE. We found similar effects in front of the Moon and attributed them to an influence of the solar wind ions reflected from the lunar surface.

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Solar Wind Proton Deceleration in Front of the Terrestrial Bow Shock

et al. 2019

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“…Furthermore, we note that analyses of Chandrayaan observations of reflected solar wind protons and a comparison of these observations to hybrid modeling found that a forward scattering function for protons off of crustal magnetic anomalies yielded the best fit to the data [ Lue et al , ; Fatemi , ]. The forward scattering of solar wind protons off of lunar magnetic anomalies is also distinctly different from solar wind proton scattering from the unmagnetized lunar surface, which has been observed as dominantly backscattered in both charged [ Saito et al , ; Lue et al , ] and neutral forms [ Schaufelberger et al , ].…”

Section: Discussionmentioning

confidence: 99%

ARTEMIS observations of the solar wind proton scattering function from lunar crustal magnetic anomalies

et al. 2017

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Despite their small scales, lunar crustal magnetic fields are routinely associated with observations of reflected and/or backstreaming populations of solar wind protons. Solar wind proton reflection locally reduces the rate of space weathering of the lunar regolith, depresses local sputtering rates of neutrals into the lunar exosphere, and can trigger electromagnetic waves and small‐scale collisionless shocks in the near‐lunar space plasma environment. Thus, knowledge of both the magnitude and scattering function of solar wind protons from magnetic anomalies is crucial in understanding a wide variety of planetary phenomena at the Moon. We have compiled 5.5 years of ARTEMIS (Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun) observations of reflected protons at the Moon and used a Liouville tracing method to ascertain each proton's reflection location and scattering angles. We find that solar wind proton reflection is largely correlated with crustal magnetic field strength, with anomalies such as South Pole/Aitken Basin (SPA), Mare Marginis, and Gerasimovich reflecting on average 5–12% of the solar wind flux while the unmagnetized surface reflects between 0.1 and 1% in charged form. We present the scattering function of solar wind protons off of the SPA anomaly, showing that the scattering transitions from isotropic at low solar zenith angles to strongly forward scattering at solar zenith angles near 90°. Such scattering is consistent with simulations that have suggested electrostatic fields as the primary mechanism for solar wind proton reflection from crustal magnetic anomalies.

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“…The backscattered H + ions appear to have a similar scattering function to that of the backscattered H-ENAs (Lue et al , 2018. However, there are clear differences in the energy spectra, where the H + ions have a higher mean energy than the H-ENAs (Lue et al 2014;Lue et al , 2018.…”

Section: Observations Of Particle Reflection From the Moonmentioning

confidence: 91%

Particles and Photons as Drivers for Particle Release from the Surfaces of the Moon and Mercury

et al. 2022

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The Moon and Mercury are airless bodies, thus they are directly exposed to the ambient plasma (ions and electrons), to photons mostly from the Sun from infrared range all the way to X-rays, and to meteoroid fluxes. Direct exposure to these exogenic sources has important consequences for the formation and evolution of planetary surfaces, including altering their chemical makeup and optical properties, and generating neutral gas exosphere. The formation of a thin atmosphere, more specifically a surface bound exosphere, the relevant physical processes for the particle release, particle loss, and the drivers behind these processes are discussed in this review.

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ARTEMIS Observations of Solar Wind Proton Scattering off the Lunar Surface

Cited by 23 publications

References 43 publications

Solar Wind Proton Deceleration in Front of the Terrestrial Bow Shock

Solar Wind Proton Deceleration in Front of the Terrestrial Bow Shock

ARTEMIS observations of the solar wind proton scattering function from lunar crustal magnetic anomalies

Particles and Photons as Drivers for Particle Release from the Surfaces of the Moon and Mercury

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