EXPERIMENTAL RESEARCH ON REFLECTANCE SPECTRA CHANGE OF SOLAR SYSTEM BODIES BY SPACE WEATERHING : A NEW CHRONOLOGY
| Project/Area Number |
18340176
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | National Astronomical Observatory of Japan |
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Principal Investigator |
SASAKI Sho National Astronomical Observatory of Japan, RISE Project, Office PROFESSOR (10183823)
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| Co-Investigator(Kenkyū-buntansha) |
NODA Hirotomo NATIONAL ASTRONOMICAL OBSERVATORY OF JAPAN, RISE Project Office, ASSISTANT PROFESSOR (10353426)
SUGITA Seiji UNIVERSITY OF TOKYO, Department of Human and Engineered Environmental Studies, ASSOCIATE PROFESSOR (80313203)
ABE Masanao Japan Aerospace Exploration Agency, ISAS, ASSOCIATE PROFESSOR (00270439)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥15,550,000 (Direct Cost: ¥14,200,000、Indirect Cost: ¥1,350,000)
Fiscal Year 2007: ¥5,850,000 (Direct Cost: ¥4,500,000、Indirect Cost: ¥1,350,000)
Fiscal Year 2006: ¥9,700,000 (Direct Cost: ¥9,700,000)
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| Keywords | PLANETARY MATERIALS / PLANETARY EXPLORATION / SOLAR SYSTEM BODIES / CHLONOLOGY / ASTEROID EVOLUTION / SPACE WEATHERING |
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| Research Abstract |
Reflectance spectra of S-type asteroids are different from those of ordinary chondrites. There are also spectral differences between lunar rocks and soils of the similar composition. These spectral mismatches are explained by the so-called space weathering. S-type asteroids exhibit more overall depletion and reddening of spectra, and more weakening of absorption bands relative to ordinary chondrites. To explain spectral differences between lunar rocks and soils as well as magnetic resonance properties of lunar soils, it was proposed the formation of nanophase metallic iron particles in soil coatings from the deposition of ferrous silicate vapor. High-velocity dust particle impacts, as well as sputtering by solar wind would be responsible for vapor formation. Our group succeeded in reproducing the spectral change expected in space weathering, using nanosecond pulse laser irradiation simulating highvelocity dust impacts. We confirmed the formation of nanophase iron particles within the vapor-deposited rim of laser-irradiated olivine and pyroxene grains using TEM.
In the present study, in order to obtain continuous bi-directional reflectance spectra from UV to NIR region, we installed a new reflectance spectrometer. Using the auto-control system, wide range of reflectance spectra can be measured continuously. To minimize the effect of spectral gaps between different detectors, we can measure the overlapped spectra. We obtained reflectance spectra of meteorite fragments as well as particulate pellets before and after laser irradiations. We selected L and LL ordinary chondrites in order to compare the measured spectra with those of asteroid Itokawa, which is a rock rubble pile observed by a multiband camera and an infrared spectrometer on board Japanese spacecraft Hayabusa. Compared with the observed spectral data of Itokawa by Hayabusa spacecraft, we confirmed that the space weathering is ongoing even on relatively young (<a few 10^7yr) asteroid Itokawa.
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Report
(3 results)
Research Products
(21 results)
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[Journal Article] Discovery of developing space weathering on an S-type asteroid of LL-chondrite composition2006
Author(s)
Hiroi, T., Abe, M., Kitazato, K., Abe, S., Clark, B. E., Sasaki, S., Ishiguro, M., Barnouin-Jha, O. S.
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Journal Title
Description
「研究成果報告書概要(欧文)」より
Related Report
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[Journal Article] Discovery of developing space weathering on an S-type asteroid of LL-chondrite composition2006
Author(s)
Hiroi, T., Abe, M., Kitazato, K., Abe, S., Clark, B.E., Sasaki, S., Ishiguro, M., Barnouin-Jha, O.S.
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Journal Title
Related Report
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[Presentation] Albedo/color heterogeneity on the surface of rubble pile asteroid Itokawa : evidence for the space weathering2007
Author(s)
Sasaki, S., Ishiguro, M., Hirata, N., Hiroi, T., Abe, M., Abe, S., Miyamoto, H., Saito, J.
Organizer
European Geosciences Union General Assembly
Place of Presentation
Vienna, Austria
Year and Date
2007-04-17
Description
「研究成果報告書概要(欧文)」より
Related Report
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