| Project/Area Number |
14340135
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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 |
固体地球物理学
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| Research Institution | Japan Aerospace Exploration Agency |
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Principal Investigator |
FUJIWARA Akira JAXA, ISAS, PROFESSOR, 宇宙科学研究本部固体惑星科学研究系, 教授 (70173482)
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| Co-Investigator(Kenkyū-buntansha) |
ABE Masanao JAXA, ISAS, RESEARCH ASSOCIATE, 宇宙科学研究本部固体惑星科学研究系, 助手 (00270439)
YANO Hajime JAXA, ISAS, RESEARCH ASSOCIATE, 宇宙科学研究本部固体惑星科学研究系, 助手 (00321571)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥14,200,000 (Direct Cost: ¥14,200,000)
Fiscal Year 2003: ¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 2002: ¥7,600,000 (Direct Cost: ¥7,600,000)
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| Keywords | ASTEROID / SAMPLE RETURN / NEAR EARTH / PLANETARY MISSION / SURFAE / REGOLITH / OBSERVATION / HYPERVELOCITY IMPACT / 探査 / 反射スペクトル / 衝突 / 1998SF36 |
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| Research Abstract |
Following researches were conducted for anticipating the surface of an asteroid Itokawa (25143 SF36), the target of the Hayabusa (MUSES-C)mission.
(1)The properties of the asteroid were reduced based on the results obtained in the opportunity for ground based observation in 2001. Following results were found from light curves of the asteroid; the rotational period is 12.13h that is longer than the average value of average asteroids, the spin axis is near the perpendicular to the ecliptic, the rotation is retrograde, and the shape is irregular. From spectroscopic observation in the optical to thermal infrared region the spectroscopic type of the asteroid was found to be S-type and the meteorite analog was found to be ordinary chondrite. The spectroscopic data at 3 micron band suggest that almost no hydrated minerals exist on the asteroid surface (less than 1%). Using the multiband spectroscopic data in the visible wavelength at various phase angles, the light scattering properties (Hapke parameters) of the asteroid surface material were investigated, and it was found that the material has the strong forward scattering property. Thermal infrared data provides the reflectivity and the surface temperature of the asteroid. These data suggest that the thermal inertia of the surface material is larger than the average asteroids. The reflectivity is higher than the average S-type asteroids.
(2)Craters were produced on gypsum targets by the oblique impact of projectiles of 4km/sec. The velocity distribution of the fragments ejected by the impact were investigated. As the result a small number of fragments of velocity less than 1m/s Is ejected. Since these fragment velocities are less than the escape velocity of the Itokawa, these fragments will fall back to and accumulate on the Itokawa and form the regolith layer.
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