Macromolecular organic matter in samples of the asteroid (162173) Ryugu

Area of Science:

• * Astrogeology and Astrobiology: Investigating the composition and origin of organic matter on asteroids.
• * Cosmochemistry: Understanding the chemical evolution of the solar system through extraterrestrial samples.

Background:

• * The Hayabusa2 mission successfully returned samples from the carbonaceous asteroid (162173) Ryugu.
• * Carbonaceous asteroids are considered primitive bodies that may hold clues to the early solar system and the origin of life.

Purpose of the Study:

• * To characterize the macromolecular organic matter present in Ryugu samples.
• * To determine the formation conditions and alteration history of this organic material.

Main Methods:

• * Spectroscopic analysis to identify functional groups and chemical features of the organic matter.
• * Morphological investigation to observe the distribution of organic carbon within the samples.
• * Isotopic analysis (Deuterium and Nitrogen-15) to infer formation environments.

Main Results:

• * Ryugu's organic matter contains aromatic and aliphatic carbon, ketone, and carboxyl groups.
• * Spectroscopic data aligns with primitive carbonaceous chondrites altered by aqueous processes.
• * Organic carbon observed as nanoglobules and diffuse material associated with phyllosilicates and carbonates.
• * Isotopic enrichments suggest formation in cold molecular clouds or the presolar nebula.

Conclusions:

• * The organic matter in Ryugu samples exhibits characteristics of both presolar origins and aqueous alteration.
• * The diversity of organic matter indicates variable water-induced alteration on Ryugu's parent body.
• * These findings contribute to understanding the inventory of organic compounds available in the early solar system.