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Rocks on asteroid Ryugu named after two late JAXA scientists

Newly announced names of rocks and an artificial crater on the asteroid Ryugu (Photo courtesy of JAXA)

TOKYO -- The Japan Aerospace Exploration Agency (JAXA) announced on Aug. 22 that it has named two rocks close to an artificial crater created by the Hayabusa2 probe on the asteroid Ryugu after two scientists who died without seeing the project succeed.

In April, Hayabusa2 successfully fired an impactor onto the asteroid's surface to form a crater over 10 meters in diameter. A large rock which moved due to the impact was named Iijima Boulder in memory of assistant professor Yuichi Iijima, who died at age 44 in 2012. Another rock which didn't move at all was named Okamoto Boulder in memory of researcher Chisato Okamoto, who died at age 38 last year. Both succumbed to illness.

To maximize the scientific significance of the impact experiment, Iijima had worked to gain cooperation from universities during the start-up phase of the Hayabusa2 project, and thus laid the foundation for its success. He had worked hard across different fields, proposing and helping to develop the digital deployable camera (DCAM3) for scientific observation.

Okamoto was a core member of the Hayabusa2 sampler development team and energetically conducted laboratory experiments in preparation to collect samples from Ryugu. She was also a member of the impact experiment team and played a central role in simulating asteroid surface conditions used in impact experiments.

In addition to the two rocks, the artificial crater, which had been previously called SCI Crater, and a triangular rock at the edge of the crater were named Omusubi-Kororin Crater and Onigiri Boulder, respectively. "Omusubi Kororin,"or "The Rolling Rice Ball," is the name of a Japanese folk tale, while "onigiri" means rice ball. The crater received its name as it looks like the rice ball-shaped rock is about to roll down into it.

Makoto Yoshikawa, a mission manager of the project, told reporters at a press conference, "I would have liked the two colleagues, who were involved in the work to form the artificial crater, to see the results. From now on, the names of the rocks will likely be cited in many research papers."

JAXA also announced the same day that the Ryugu capsule which is carrying rock samples from Ryugu, will land in an area in southern Australia upon its return to Earth -- the same place where the first Hayabusa capsule successfully landed.

(Japanese original by Etsuko Nagayama, Opinion Group, and Tomohiro Ikeda, Science & Environment News Department)

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