Scientific study of samples
Before the capsule was extracted from the protecting plastic bag, it was inspected using X-ray CT to determine its condition. Then the sample canister was extracted from the reentry capsule. The surface of the canister was cleaned using pure nitrogen gas and carbon dioxide; it was then placed in the canister opening device. The internal pressure of the canister was determined by a slight deformation of the canister as the pressure of the environment nitrogen gas in the clean chamber was varied. The nitrogen gas pressure was then adjusted to match the internal canister pressure to prevent the escape of any gas from the sample upon the opening of the canister.
Confirmation of asteroid particles
On 16 November 2010, JAXA confirmed that most of the particles found in one of two compartments inside the Hayabusa sample return capsule came from Itokawa. Analysis with a scanning electron microscope identified about 1,500 grains as rocky particles, according to the JAXA press release. After further studying the analysis results and comparison of mineral compositions, most of them were judged to be of extraterrestrial origin, and definitely from the asteroid Itokawa.
According to Japanese scientists, the composition of Hayabusa's samples was more similar to meteorites than known rocks from Earth. Their size is mostly less than 10 micrometers. The material matches chemical maps of Itokawa from Hayabusa's remote sensing instruments. The researchers found concentrations of olivine and pyroxene in the Hayabusa samples.
Further study of the samples had to wait until 2011 because researchers were still developing special handling procedures to avoid contaminating the particles during the next phase of research.
In 2013 JAXA announced that 1500 extraterrestrial grains had been recovered, comprising the minerals olivine, pyroxene, plagioclase and iron sulphide. The grains were about 10 micrometers in size. JAXA performed detailed analyses of the samples by splitting particles and examining their crystal structure at SPring-8.
The August 26, 2011, issue of Science devoted six articles to findings based on dust collected by Hayabusa. Scientists' analysis of the dust from Itokawa suggested that it had probably originally been part of a larger asteroid. Dust collected from the asteroid surface was believed to have been exposed there for about eight million years.
Dust from Itokawa was found to be "identical to material that makes up meteorites." Itokawa is an S-type asteroid whose composition matches that of an LL chondrite.