We analyze the types and quantities of elements in the samples from the asteroid Ryugu using a technique called X-ray fluorescence analysis.
This measurement technique works by irradiating material with X-rays and capturing the light that is emitted, called “fluorescent X-rays.” Since these emitted rays are unique to each element, it reveals the elements that compose the material.

In samples of rocks, meteorites and other materials, the distribution of elements in their constituent minerals tends to be uneven, so analytical results may vary with the measurement location. Therefore, to evaluate the chemical composition of the parent body of the sample, the asteroid Ryugu more accurately, the Chemical Analysis Team conducts two types of analysis:(1) “bulk analysis,” and (2) ”microanalysis”. Bulk analysis requires a sufficient quantity of sample to represent the chemical composition of the whole parent body. Microanalysis, on the other hand, requires minute amounts of the sample, and analyzes different tiny areas of the sample, thereby compensating the sample heterogeneity.

HORIBA has decided to participate in this project because of its unique X-ray analysis technology, which is particularly valuable for the analysis of limited sample quantities, as described in (2) above.

Ryugu is believed to contain a large amount of carbon derived from organic matter, so this analysis will search for the presence of carbon, as well as other elements.

In analyzing such precious samples, it is vital to avoid contaminating these at all costs. Normally, to optimize measurement conditions, chemical analysis requires some sort of pretreatment on the samples, such as grinding into fine powder or adding chemical agents for measurement. But we do not need to perform any such pretreatment of samples. Our technology enables a non-destructive and non-contact analysis by minimizing sample contamination and maintaining conditions that is suitable for analysis using the sample cell which we have exclusively developed for this project. After the analysis, we undertake chemical treatment and combustion of samples to perform further analyses aimed at yielding more detailed information, to reveal even more of the mysteries surrounding the nature and origin of Ryugu.

Reference: HORIBA website: X-ray Fluorescence Analyzers (XRF)