First compositional analysis of Ryugu
14 July 2022
It is important to clarify the characteristics of the celestial body that best preserves the mineral and molecular phases formed in the early stage of the solar system’s evolution to understand the process that led to the formation of various planets. The Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) brought back samples taken on the surface of Ryugu Type C asteroids 1 and 2 for the first time. Currently, it is preserved at the Extraterrestrial Life Exploration Research Center at the Institute of Space and Astronautical Science, Sagamihara City, and primary non-destructive analysis is being performed.
The analysis of the first material brought back to Earth from Ryugu, an asteroid rich in carbon, was presented in two papers published in Nature Astronomy. These high-carbon asteroids provide clues to the early history of the solar system and the formation of organic and hydrated minerals, which are the building blocks of life. Ryugu is a diamond-shaped near-Earth asteroid with a diameter of about 1 km. In December 2020, the Hayabusa2 spacecraft brought back 5.4 grams of samples from the asteroid’s surface.
Two papers that analyzed Ryugu samples
In the first of two papers that analyzed Ryugu samples, Toru Yada and his colleagues found that the samples are very dark, reflect only 2% of the light hit, have a high porosity of 46%, and are larger than any meteorite studied, so far In the second paper, Cédric Pilorget and colleagues determined the sample’s composition using a microscope that can capture images at different wavelengths of visible light and infrared light.
The authors found that this sample was a mixture of various organic matter embedded in a hydration matrix such as clay. However, some parts are made of different materials, such as carbonates and volatile compounds. The authors conclude that the content of this sample is one of the most primitive materials ever obtained in our laboratory, forming a unique collection for studying the origin and evolution of the solar system and at the same time showing a model of sample returns from future planets.