The study of soil samples from the asteroid Ryugu showed that its depths contain a lot of water and organic volatiles. This confirms that the object consists of primordial materials from the birth of the Solar System.
(162173) Ryugu is a near-Earth asteroid of the Apollo group, the trajectory of which crosses both the Earth’s and Martian orbits. At the end of 2014, the Japanese automatic station Hayabusa-2 was launched towards it.
It arrived at the asteroid in 2018 and collected soil samples from its surface after bombing it with explosives. In addition to these operations, the station also collected data on the mass, size, shape, density, and geological properties of the asteroid and photographed its surface.
Importance of the mission
The mission organizers hope that by studying the soil from Ryugu, scientists will be able to understand how the Sun, Earth, and other objects formed. However, for this, it is necessary to prove that the collected samples of the asteroid’s rocks are really close in composition and properties to the primordial materials of the Solar System.
Planetary scientists, led by the scientific director of the Hayabusa-2 mission, received the first evidence of this kind thanks to the non-destructive analysis of rocks collected by the apparatus. Planetologists studied the structure of the samples and determined their approximate chemical and mineral composition using a hyperspectral microscope.
Composition of Ryugu’s soil
Their comparison with samples of matter from other chondrite asteroids, fragments of which fell to Earth in the distant past, showed that Ryugu is very similar in structure and mechanical properties to relatively rare meteorites from the CI-chondrite class.
In the samples of such meteorites, as a rule, there is a lot of water and at the same time, they are as close as possible in the ratio of other elements to the plasma of the Sun and the primary elements of the Solar System.
At the same time, the Ryugu soil turned out to be much more porous and fragile than the known samples of meteorites-chondrites. This speaks of the primordial nature of the interior of this celestial body.
This is also supported by the fact that in individual grains of dust from Ryugu, scientists found many water molecules, as well as possible traces of volatile organic compounds containing hydrogen and carbon, as well as nitrogen and hydrogen. In addition to this, planetary scientists have found traces of carbonates and other compounds resulting from the interaction of water and various minerals.
In this second study, the researchers determined the composition of the sample using a microscope that can capture images at different wavelengths of light in the visible and infrared spectra.
All this, according to astronomers, confirms that there are indeed samples of primordial materials in Ryugu’s soil. This expands the unique collection of extraterrestrial materials, the study of which brings us closer to understanding the origin and evolution of the solar system. Scientists hope that their further studies using destructive methods will make it possible to understand what organic compounds are present in the asteroid.
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• Lanese, N. (2021, December 20). Bits of asteroid Ryugu are among ‘most primordial’ materials ever examined. LiveScience.
• Okada, T., Fukuhara, T., & Tanaka, S. (2020, March 16). Highly porous nature of a primitive asteroid revealed by thermal imaging.
• Pilorget, C., Okada, T., & Hamm, V. (2021, December 20). First compositional analysis of Ryugu samples by the micromega hyperspectral microscope. Nature News.
• Starr, M. (n.d.). We finally have the first-ever analysis of Stardust retrieved from the Ryugu asteroid. ScienceAlert.
• Yada, T., Abe, M., & Okada, T. (2021, December 20). Preliminary analysis of the Hayabusa2 samples returned from C-Type asteroid Ryugu. Nature News.