In Situ Observations of Ions and Magnetic Field Around Phobos: The Mass Spectrum Analyzer (MSA) for the Martian Moons eXploration (MMX) Mission

Yokota, Shoichiro; Terada, Naoki; Matsuoka, Ayako; Murata, Naofumi; Saito, Yoshifumi; Delcourt, Dominique; Futaana, Yoshifumi; Seki, K.; Schaible, Micah J.; Asamura, Kazushi; Kasahara, Satoshi; Nakagawa, Hiromu; Nishino, Masaki N.; Nomura, Reiko; Keika, Kunihiro; Harada, Yuki; Imajo, Shun

doi:10.21203/rs.3.rs-130696/v1

Cited by 2 publications

(2 citation statements)

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“…Furthermore, the scattering of protons from the surface of Phobos has recently been studied (Futaana et al., 2010, 2021). The Martian Moons eXploration (MMX) mission will significantly add to observations of scattered ions (Yokota et al., 2021), but it is not equipped with an instrument for ENA measurements. The quantification of the total amount of reflected solar wind protons from the surface of Phobos will therefore not be possible in the same manner as it has been achieved for the Moon.…”

Section: Discussionmentioning

confidence: 99%

Deducing Lunar Regolith Porosity From Energetic Neutral Atom Emission

Szabo

Poppe

Biber

et al. 2022

Geophysical Research Letters

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The surfaces of airless bodies are covered by a porous regolith, a loose ensemble of rocks and dust grains, due to a multitude of erosion and impact processes over billions of years (McKay et al., 1991). Its upper layers determine how those planetary bodies are observed as their surface morphology strongly affects optical properties (Hapke, 2008;Vernazza et al., 2012). The porous structure of stacked grains will also influence the interaction of any planet, moon, or asteroid with its environment or precipitating radiation. Especially the effect of porosity on thermal conductivity has been of recent interest (Ryan et al., 2022;Wood, 2020). The porosity of the upper regolith is also connected to the mechanical properties of the grain stacking (Kiuchi & Nakamura, 2014) as well as grain transport processes across a planetary surface (Schwan et al., 2017;Vernazza et al., 2012). While a large number of studies of lunar regolith have been performed, the porosity of the pristine upper regolith, defined as the ratio of voids to the total volume in the region near the surface that is accessible for precipitating radiation, is difficult to deduce from returned samples and requires non-invasive methods (Ohtake et al., 2010). Early investigations estimated a porosity value between 0.8 and 0.9 from reflectance measurements (Hapke & van Horn, 1963). Similarly, Ohtake et al. ( 2010) found a high porosity for the Apollo 16 sample site, which was confirmed by Hapke and Sato (2016), determining a porosity of 0.83 ± 0.03 for the upper lunar regolith at this specific site. This value for the upper regolith differs from the result of studies with returned samples of 0.52 ± 0.02 for the upper 15 cm of the lunar soil (Carrier III et al., 1991). Impacting particles, such as photons, ions, or electrons, however, have much smaller interaction regions on the order of millimeters (Hapke & Sato, 2016). It is thus questionable how applicable measurements of the porosity from returned samples are

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Section: Discussionmentioning

confidence: 99%

Deducing Lunar Regolith Porosity From Energetic Neutral Atom Emission

Szabo

Poppe

Biber

et al. 2022

Geophysical Research Letters

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“…JAXA's Martian Moons Exploration mission (MMX) is set to explore Phobos starting in 2024 and will carry two magnetometers and an ion electrostatic analyzer (Yokota et al., 2021). We highlight in this article that solar wind protons backscattered by Phobos may have never been observed so far, neither by MEX nor MAVEN.…”

Section: Discussion: Why Maven Did Not Detect Backscattered Solar Win...mentioning

confidence: 99%

MAVEN Proton Observations Near the Martian Moon Phobos: Does Phobos Backscatter Solar Wind Protons?

Deniau

Nénon

André

et al. 2022

Geophysical Research Letters

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Backscattering of solar wind ions by a planetary surface is a fundamental process that may occur at all bodies exposed to the solar wind and unprotected by a thick atmosphere, that is, the Moon, Mercury, the moons of Mars, dwarf planets, asteroids, and comets. The overarching questions at stake include: (a) what are the key parameters that control the efficiency and angular distribution of solar wind ion backscattering, including solar wind parameters (density, bulk speed, temperature, composition) and surface properties (composition, density, porosity), (b) what can be learnt about a surface from the observation of backscattered particles, and (c) does the mass loading of backscattered ions upstream of an airless body influence its global interaction with the solar wind (e.g., Harada & Halekas, 2016)?At the Moon, JAXA's Nozomi, JAXA's Kaguya, ISRO's Chandrayaan-1, and NASA's ARTEMIS missions have opened an era of detailed characterization of solar wind ion backscattering (e.g.,

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In Situ Observations of Ions and Magnetic Field Around Phobos: The Mass Spectrum Analyzer (MSA) for the Martian Moons eXploration (MMX) Mission

Cited by 2 publications

References 98 publications

Deducing Lunar Regolith Porosity From Energetic Neutral Atom Emission

Deducing Lunar Regolith Porosity From Energetic Neutral Atom Emission

MAVEN Proton Observations Near the Martian Moon Phobos: Does Phobos Backscatter Solar Wind Protons?

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