Asteroid Ryugu Shifted to Current Orbit 5 M. Years Ago
Newsfrom JapanScience Society
Tokyo, Oct. 21 (Jiji Press)--A team of researchers in Japan said Ryugu traveled to settle into its current orbit around five million years ago, based on analysis of gas components in sand samples brought back to the Earth from the asteroid by the country's Hayabusa2 explorer.
The findings of the team, including researchers from Kyushu University, the University of Tokyo and the Japan Aerospace Exploration Agency, or JAXA, were released in the U.S. journal Science and other papers on Friday.
Ryugu is believed to have traveled from an asteroid belt between Mars and Jupiter to the current orbit between the Earth and Mars. It had been unknown when the asteroid had made the journey.
The team heated 16 grains of sand from the samples to extract noble gases including helium and xenon, as well as nitrogen. It conducted isotope analysis to find out when and how the gases were generated.
It found that the grains of sand had trapped the noble gases when the solar system was formed around 4.6 billion years ago. The analysis also showed that noble gases that had been generated after being exposed to cosmic rays some 1 to 2 meters below Ryugu's surface were present in the sand.
[Copyright The Jiji Press, Ltd.]