Illuminating ancient origins of 4BN year-old Asteroid Ryugu

Los Angeles CA (SPX) Oct 30, 2024
Researchers at the Advanced Photon Source (APS) recently participated in an international study of fragments from asteroid 162173 Ryugu, collected by a Japanese space mission. The APS, a light source facility operated by the Department of Energy, employed Mossbauer spectroscopy - a technique uniquely suited to studying small samples - on specks of dust from Ryugu. The results revealed that the asteroid originated in the outer solar system as part of a much larger body formed over 4 billion years ago before moving to its current orbit within 60,000 miles of Earth.

The analysis of these minute asteroid fragments, sent to APS for examination via powerful X-ray beams, revealed crucial details about Ryugu's past and chemical composition. Utilizing Mossbauer spectroscopy, scientists discovered that Ryugu initially consisted primarily of ice, which evolved as it journeyed across space and experienced temperature changes over millions of years. The fragments held elements that provided essential data on the conditions at the solar system's outer edges where they originated.

A critical aspect of the APS's contribution was the ability of the facility's X-ray beam to focus down to 4 microns, enabling detailed readings of these fragments, which ranged from 400 microns to one millimeter in diameter. This precision allowed scientists to determine the oxidation state of iron in each sample, revealing that Ryugu's structure was once porous and ice-laden. Over time, however, the ice melted, leaving behind a fine-grained, iron-rich residue, including pyrrhotite, a type of iron sulfide absent in meteorites similar to Ryugu fragments. This discovery provided new constraints on the temperature and location of Ryugu's parent asteroid at the time of its formation.

Together with findings from numerous research groups, APS data offered a comprehensive view of Ryugu's journey through space. The data illuminated its evolution from a large, icy body in the outer solar system to its current, rocky form, rich in unique elements from its ancient origin.

Research Report:Formation and Evolution of Carbonaceous Asteroid Ryugu: Direct Evidence from Returned Samples