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Dedicating New Year’s to plan for the touchdown on Ryugu

When the Hayabusa2 explorer finally arrived at the asteroid Ryugu, the entire surface, it turned out, was covered in boulders. There were virtually no flat areas where it could touch down safely. If it had attempted a landing, it might have hit a rock and been damaged.
The question of how to overcome this challenge was heatedly debated at the end of 2018. A meeting to discuss the issue even took place at the very end of the year, on December 27 2018.
The plan originally proposed by the JAXA Hayabusa2 project team was judged impractical by the personnel responsible for the spacecraft’s attitude control (controlling its orientation). The team was in a quandary. By the time New Year’s arrived here on earth, they feared, they might still not have a found a way to land the probe on Ryugu. Then, a little after 9:00 p.m. on December 27, a new plan arrived from JAXA Hayabusa2 project team, which ultimately led to the success of the first touchdown. Mission operations were suspended during December 2018, when the explorer was unable to communicate with earth due to the relative positions of the explorer and the asteroid — a phase of the mission called the “solar conjunction operation.” The team too had originally intended to take a break, but in the end they spent the entire time including New Year’s holidays studying touchdown options. Then they sacrificed their year-end holidays to planning for the touchdown on Ryugu, until the plan finally got the go-ahead in the New Year.

Photo of the surface of Ryugu taken by the mini-rover MINERVA-II1 Rover-1B, which was dropped on the asteroid in September 2019. The photo, taken on September 23 at approximately 10:10 a.m. Japan Standard Time, shows the surface covered in boulders, which proved a serious obstacle to touchdown plans for the Hayabusa2 explorer.

Interview and article by Ayano Akiyama
Published March 30, 2020

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