A chondrule-like object captured by space-exposed aerogel on the international space station

作者：Noguchi T^*; Nakamura T; Ushikubo T; Kita N T; Valley J W; Yamanaka R; Kimoto Y; Kitazawa Y

来源：Earth and Planetary Science Letters, 2011, 309(3-4): 198-206.

DOI：10.1016/j.epsl.2011.06.032

• micrometeoroid
• hypervelocity capture
• international space station
• transmission electron microscopy
• oxygen isotopic ratios
• SIMS

Here we report on the mineralogy, petrography, and oxygen-isotope compositions of a micrometeoroid captured on the international space station. This micrometeoroid has the texture of a porphyritic olivine chondrule. Because hydrated phases were not identified in the micrometeoroid and because Ni-rich sulfide in it does not show exsolution of pentlandite on the TEM scale, the micrometeoroid probably escaped low temperature events such as aqueous alteration on its parent body. However, the mean value and standard deviation of Cr(2)O(3) wt.% in olivine in the micrometeoroid suggest that the micrometeoroid experienced weak thermal metamorphism. Oxygen isotope ratios of pyroxene and olivine in the micrometeoroid are similar to those of chondrule-like objects in comet 81P/Wild2 and coarse-grained crystalline micrometeorites as well as those in chondrules in major types of carbonaceous chondrites. These data suggest that the micrometeoroid is a fragment of a chondrule-like object that was derived from a primitive parent body that experienced thermal metamorphism.

• 出版日期2011-9-15