A STUDY ON CHANGES OF REFLECTANCE SPECTRA OF PLANET-FORMING MINERALS : DEVELOPMENT OF SPACE WEATHERING SIMULATOR

行星形成矿物反射光谱变化的研究:空间风化模拟器的开发

• 批准号: 11440158
• 负责人: SASAKI Sho
• 金额: $ 6.02万
• 依托单位: THE UNIVERISITY OF TOKYO
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11440158/
• 关键词: SPACE WEATHERING; REFLECTANCE SPECTRUM; REGOLITH; ASTEROIDS; LUNAR SOIL; PULSE LASER; NANOPHASE PARTICLES; COLISSIONS OF INTERPLANETARY DUST PARTICLES; 赤化; カンラン石; 輝石; 斜長石; 蒸発と凝縮

"Space weathering" is a proposed process responsible for the darkening and reddening of planetary surface materials and for decreasing depths of their optical absorption bands. It may explain the spectral mismatches between lunar soils and rocks as well as between asteroids and meteorites. The formation of nanophase iron particles on regolith grains due to micrometeorite impacts and/or solar wind irradiation is considered as the cause of the optical properties changes. Various laboratory simulations of space weathering have been performed. Nano-second pulse laser irradiation reproduced the optical changes associated with the space weathering. whereby compositional dependence of weathering of asteroids was also explained. However, the existence of nanophase iron particles has been a conjecture. Here we report observations of olivine samples after pulse-laser irradiation by transmission electron microscopy (TEM). Vapor-deposited amorphous rims of olivine grains have nanophase iron (aFe) particles (several to 30 nm in size) similar to those observed in lunar space weathering. Reduction by hydrogen atoms is not necessary to form nanophase iron particles. Our results should give additional support to the idea that ordinary chondrites have come from S-type asteroids, providing constraints on the surface exposure age of asteroids.

“太空风化”是一个提议的过程，负责行星表面材料的变暗和变红，并减少其光学吸收带的深度。它可以解释月球土壤和岩石之间以及小行星和陨石之间的光谱不匹配。由于微陨石撞击和/或太阳风照射，在风化层颗粒上形成纳米相铁颗粒被认为是光学性质变化的原因。已经进行了各种空间风化的实验室模拟。纳秒脉冲激光辐照再现了与空间风化有关的光学变化。由此也解释了小行星风化的成分依赖性。然而，纳米铁颗粒的存在一直是一个猜想。本文报道了用透射电子显微镜（TEM）观察脉冲激光照射后的橄榄石样品。气相沉积的橄榄石颗粒的无定形边缘具有纳米相铁（aFe）颗粒（大小为几至30纳米），与在月球空间风化中观察到的颗粒相似。形成纳米铁颗粒并不需要氢原子的还原作用。我们的研究结果将进一步支持普通球粒陨石来自s型小行星的观点，为小行星的表面暴露年龄提供约束。

项目成果

Shitaba,H., et al.: "Micro-particle acceleration by a Vande Graaff accelerator and application to space and material sciences"Radiation Physics and Chemistry. (in press). (2001)

Shitaba,H. 等人：“Vande Graaff 加速器的微粒加速及其在空间和材料科学中的应用”辐射物理和化学。

Hasegawa,S: "Design of electrostatic accelerators for the development of microparticle detectors in Japan"Adv,in Space Res.. 23. 119-122 (1999)

长谷川，S：“用于日本微粒探测器开发的静电加速器的设计”Adv，in Space Res.. 23. 119-122 (1999)

Shibata,H., et al.: "Micro-particle acceleration by a Vande Graaff accelerator and application to space and material sciences"Radiation Physics and Chemistry. (in press). (2001)

Shibata, H. 等人：“Vande Graaff 加速器的微粒加速及其在空间和材料科学中的应用”辐射物理和化学。

Yamada,M., et al.: "Simulation of Space Weathering of Planet-Forming Materials : Nanosecond Pulse Laser Irradiation and Proton Implantation on Olivine and Pyroxene Samples"Earth Planets Space. 51. 1255-1265 (1999)

Yamada,M. 等人：“行星形成材料的空间风化模拟：纳秒脉冲激光辐照和橄榄石和辉石样品上的质子注入”地球行星空间。

S.Sasaki, K.Nakamura, Y.Hamabe, E.Kurahashi, and T.Hiroi: "Production of iron nanopharticles by laser irradiation in a simulation of lunar-like space weathering"Nature. (in press). (2001)

S.Sasaki、K.Nakamura、Y.Hamabe、E.Kurahashi 和 T.Hiroi：“在类月空间风化模拟中通过激光照射生产铁纳米颗粒”《自然》。