Related Experiment Video
Updated: May 29, 2026

In Situ Detection and Single Cell Quantification of Metal Oxide Nanoparticles Using Nuclear Microprobe Analysis
Published on: February 3, 2018
Neutron activation analysis of a particle returned from asteroid Itokawa
M Ebihara1, S Sekimoto, N Shirai
1Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan. ebihara-mitsuru@tmu.ac.jp
Abstract:
A single grain (~3 micrograms) returned by the Hayabusa spacecraft was analyzed by neutron activation analysis. This grain is mainly composed of olivine with minor amounts of plagioclase, troilite, and metal. Our results establish that the Itokawa sample has similar chemical characteristics (iron/scandium and nickel/cobalt ratios) to chondrites, confirming that this grain is extraterrestrial in origin and has primitive chemical compositions. Estimated iridium/nickel and iridium/cobalt ratios for metal in the Itokawa samples are about five times lower than CI carbonaceous chondrite values. A similar depletion of iridium was observed in chondrule metals of ordinary chondrites. These metals must have condensed from the nebular where refractory siderophile elements already condensed and were segregated.
Related Concept Videos
Subatomic Particles
Atomic Emission Spectroscopy: Lab
Atomic Emission Spectroscopy: Overview
Nuclear Fission
Atomic Absorption Spectroscopy: Atomization Methods
Nuclear Transmutation

