JpGU-AGU Joint Meeting 2017

Presentation information

[EE] Oral

P (Space and Planetary Sciences) » P-PS Planetary Sciences

[P-PS02] [EE] Small Bodies: Exploration of the Asteroid Belt and the Solar System at Large

Sun. May 21, 2017 10:45 AM - 12:15 PM 103 (International Conference Hall 1F)

convener:eleonora ammannito(University of California Los Angeles), Taishi Nakamoto(Tokyo Institute of Technology), Masanao Abe(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Christopher T Russell(University of California Los Angeles), Sei-ichiro WATANABE(Division of Earth and Planetary Sciences, Graduate School of Science, Nagoya University), Chairperson:Sei-ichiro Watanabe(Nagoya University)

11:45 AM - 12:00 PM

[PPS02-11] Estimation of the reflectance spectra of C-type asteroids affected by solar wind proton irradiation

*Yusuke Nakauchi1, Masanao Abe2,1, Toru Matsumoto2, Kohei Kitazato3, Akira Tsuchiyama4, Kohtaku Suzuki5, Yoshinori Nakata5 (1.SOKENDAI [The Graduate University for Advanced Studies], 2.The Japan Aerospace Exploration Agency, 3.University of Aizu, 4.Kyoto University, 5.The Wakasawan Energy Research Center)

Keywords:space weathring, solar wind, C-type asteroid

Asteroids and meteorites are thought to retain information on the early solar system. In particular, planetesimals similar to C-type asteroids and/or parent bodies of carbonaceous chondrites may have carried water and organics to the earth. However, meteorites do not retain direct evidence for which parent body they come from. Nevertheless, reflectance spectra suggest that carbonaceous chondrites may be from C-type asteroids.
The surface of airless bodies, however, exhibit spectra affected by space weathering effect. Recent studies suggest that the influence of solar wind implantation cannot be ignored in near earth airless bodies [Ichimura et al., 2012]. The absorption strength around 3 μm of reflectance spectra of silicate minerals which mainly contained in carbonaceous chondrites was changed by hydrogen irradiation [Nakauchi et al., 2014]. This change strongly suggests that hydroxyl group and/or H2O were formed by hydrogen implantation.
In this study, based on the previous our study, the spectral change by hydrogen implantation on the C-type asteroids is estimated by spectral mixing model. Only the reflectance spectra of olivine, antigorite and saponite were taken into consideration of hydrogen implantation and other reflectance spectra of minerals and carbonaceous chondrite were obtained from the RELAB database.
After hydrogen irradiation, the absorption strengths of reflectance spectra estimated by mixing model showed different changes depend on carbonaceous chondrite groups. In CI and CM chondrites, the absorption strength at 2.77 μm changed strongly. On the other hand, the weathered spectra of CR and CV chondrites showed weaker change from 2.8 μm. These differences were suggested to be useful for meteorite type estimation.
When we estimate carbonaceous chondrite types using reflectance spectra on C-type asteroids, then, the space weathering effect of solar wind protons must be considered.