Ryugu

Ryugu is the near-Earth asteroid 162173 Ryugu, previously designated 1999 JU3, a small carbonaceous body visited by JAXA's Hayabusa2 mission. It was discovered on May 10, 1999, by the LINEAR program. The name Ryugu, meaning Dragon Palace in Japanese folklore, was chosen in a public process and approved by the International Astronomical Union.

Ryugu is an Apollo-group near-Earth asteroid with an orbit that crosses Earth's and has a semi-major axis around 1.0 AU. It is dark and carbon-rich, with a diameter of about 0.9 km. The rotation period is roughly 7.6 hours. The body has an irregular, bilobed shape and is considered a rubble-pile with a rough, boulder-strewn surface.

Launched in 2014 and arriving at Ryugu in 2018, Hayabusa2 mapped the surface, deployed the MASCOT lander and two MINERVA-II rovers, and used an impactor to create a crater and expose subsurface material. It collected samples from multiple sites with a sampling horn and delivered a sample-return capsule to Earth in December 2020, carrying about 5.4 grams of material to the Australian desert.

Analyses of the Ryugu samples found hydrated minerals and organic-rich material, consistent with primitive solar-system matter. The findings support models of water delivery and the presence of complex organics in early solar-system bodies and help illuminate the origins of life-related materials on Earth.