Leonard David's INSIDE OUTER SPACE

Hayabusa2 image captured near the touchdown site roughly a minute after touchdown. The photograph was taken at roughly 80 feet (25 meters) with the Optical Navigation Camera – Wide angle (ONC-W1) on February 22, 2019 (JST).
The color of the region beneath the spacecraft’s shadow differs from the surroundings and has been discolored by the touchdown. At the moment, the reason for the discoloration is unknown but it may be due to the grit that was blown upwards by the spacecraft thrusters or by the bullet (projectile) shot from Hayabusa2 in the sampling process.
Credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST

Japan’s Hayabusa2 successfully touched down on asteroid Ryugu on February 22 (JST). It turns out that the gentle cosmic kiss between spacecraft and space rock wasn’t without incident.

Hayabusa2 touchdown region overlapped with the planned touchdown site. The touchdown spot sits at the center of the discolored area. Hayabusa2 researchers explain that an accurate touchdown point will be examined during a more detailed analysis in the future. Also shown is the white target marker, which is shining in the reflected sunlight.
Credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST

In a posted update from the team: “It was a long week for the team members! Until just before the start of the descent, we examined every aspect of landing plan to remove all doubts and increase our level of confidence. We polished the landing sequence to perfection! The team’s all-out battle was rewarded in the best possible way. We are all looking forward to the report of the results.”

Ingenuity after touchdown

“We had to use a little ingenuity for the motion of Hayabusa2 after touchdown,” the team posting adds.

“The spacecraft rose obliquely after touchdown due to the angle of the ground. This meant that in order to return to the home position, it was necessary to exert a force in a direction difficult to achieve due to the orientation of the spacecraft thrusters.”

Position of the planned touchdown site and target marker. The size of the circle at the planned site is 20 feet (6 meters) in diameter. The X indicates the position of the target marker that was dropped at a later date.
Credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST

Perfect somersault

“We therefore added a twist in the spacecraft attitude by performing a 1/20 turn about the Y-axis and 1/6 turn about the Z-axis before firing the thrusters, and then reversing this twist to return to the original position. This change in attitude allowed the thrusters to fire efficiently,” the posting explains.

“Hayabusa2 achieved a perfect somersault over Ryugu –like a ‘lunar somersault’— and then returned to the home position in a dignified manner. It was an ingenious performance to the end.”

Now the Hayabusa2 project team has turned to evaluating the technical score of the touchdown operation.