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| Titel |
The effect of solar wind parameters on proton backscattering from the Moon: Chandrayaan-1/SARA observations |
| VerfasserIn |
Charles Lue, Yoshifumi Futaana, Stas Barabash, Martin Wieser, Peter Wurz, Anil Bhardwaj |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075470
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| Zusammenfassung |
| Backscattered solar wind protons from the lunar surface were first observed by Kaguya [1], at a backscattering efficiency of 0.1% – 1% of the incident solar wind proton flux. Subsequent observations by Chandrayaan-1 [2] and IBEX [3] revealed that a larger fraction (10% – 20%) of the solar wind protons is backscattered as energetic neutral hydrogen atoms. In the present study, we use observations from the Solar Wind Monitor (SWIM) of SARA on Chandrayaan-1 to investigate the backscattered proton fraction’s dependence on the solar wind parameters. Our observations indicate a large variability in the proton backscattering fraction that strongly depends on the solar wind velocity (~0.01% to ~1% for solar wind velocities of 250 to 550 km/s). The observed backscattered proton fluctuation agrees well with a model of proton survivability against neutralisation as a function of impact velocity, available from theoretical and laboratory studies [4]. This dependence on impact velocity is important to take into account when modelling the interaction between airless bodies and their surrounding plasma. An enhanced understanding of the particle-surface interaction may open up for remotely determining properties of the surface and/or the impacting particles.
[1] Saito, Y. et al. (2008), Geophys. Res. Lett., 35, L24205, doi:10.1029/2008GL036077.
[2] Wieser, M. et al. (2009), Plan. Space Sci., 57(14), 2132-2134, doi:10.1016/j.pss.2009.09.012.
[3] McComas, D.J. et al. (2009), Geophys. Res. Lett., 36, L12104, doi:10.1029/2009GL038794.
[4] Niehus, H. et al. (1993), Surf. Sci. Rep. 17(4), 213-303, doi:10.1016/0167-5729(93)90024-J. |
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