TEM observation of carbonaceous particles in Hayabusareturned samples.
M. Uesugi1, H. Naraoka2, F. Kitajima2, M. Ito3, H. Yabuta4, Y.
Takano3, H. Mita5, T. Yada1, Y. Karouji1, T. Okada1 and M. Abe1.
1
JAXA/ISAS. 2Kyushu University. 3JAMSTEC. 4Osaka
University. 5Fukuoka Inst. Tech.
E-mail: uesugi@planeta.sci.isas.jaxa.jp.
Introduction: Preliminary examination of carbonaceous
materials of Hayabusa-returned samples, classified as category 3,
were processed for 1 year, and we obtained information of theirorigin. Texture and chemical composition of them obtained byscanning electron microscopy with energy dispersive X-ray
spectrometry (SEM-EDS) analysis indicate that those particles
would have several origins, and then some of them might beterrestrial contamination.
Ito et al. [1] analyzed three category 3 particles by
NanoSIMS and did not found any exotic isotopic anomalies.
However, they noticed that it is difficult to conclude their origin
as terrestrial, and further investigation about their molecular
structure, microstructure and chemical compositions areimportant for the determination of their precise origin.
In this presentation, we report results of transmission electron
microscopy (TEM) observation of category 3 particles andpotential contaminants such as fluoro rubber and silicon rubber,
those used in clean chamber and clean room. We compared theirmicrostructure and discuss the origin of category 3 particles
including possibility of their extraterrestrial origin.
Experiment: All category 3 particles were fixed by pressing
on gold (Au) or indium (In) plates using sapphire glass. We canobserve the sample through the sapphire glass during pressing
and thus reduce the accidental loss of the samples. Ultra-thinsections (UTSs) were extracted from the pressed samples byfocused ion beam (FIB) after the application of SIMS analysis,
FT-IR and Raman spectroscopy.
Fluoro rubber and silicon rubber were also pressed on Inplate, and a particle corrected from a contamination coupon
exposed to clean room of Hayabusa 2 construction was pressedon Au plate. Their UTSs were also extracted by same procedureof category 3 particles.
After the analysis of Extended x-ray absorption fine structure(EXAFS) , we observed the UTSs by TEM/STEM (JEOL FEM2800 and JEM-2100F).
Results: We found Si and N distribution in RB-QD04-004702 and RA-QD02-0120 in TEM-EDS analysis [2]. Although Si
distribution is apparent in Si rubber, it did not include N. Inaddition, Si rubber we observed contains amount of Ti-oxide
inclusions which would be doped for coloring of the rubber. Suchinclusions were not observed in category 3 particles. We also
found several inclusions such as Mg or Zn in fluoro rubber. Thus,
artificial rubbers contain remarkable inclusions, and we candistinguish them from other materials.
On the other hand, we found similar Si and N distribution in
UTS of a contamination coupon particle of Hayabusa2
construction clean room. The particle shows uniform N
distribution and heterogeneous distribution of Si, which is closely
resemble to the category 3 particles. Based on these results, wewill be able to make further discussions for the origin of thecategory 3 particles.
References: [1] Ito et al. 2014. Earth Planets. Space 66:91.
[2] Uesugi et al., 2014 Earth Planets. Space in press