The successful landing of Hayabusa2 on asteroid Ryugu

Image from just after touchdown of of Hayabusa2 on asteroid Ryugu. Credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST.

The National Research and Development Agency Japan Aerospace Exploration Agency (JAXA) have successfully executed the operation to touch down on asteroid Ryugu with the explorer Hayabusa2 having retrieve a sample from the surface last Friday, 22 of February. 

The operational sequence included shooting a projectile into the asteroid to collect its sample material. Figure 1 shows an image taken with the Optical Navigation Camera – Wide angle (ONC-W1) during the spacecraft ascent after touchdown, which shows the image from just after touchdown. 

Figure 1: Image captured near the touchdown site immediately after touchdown. The photograph was taken with the Optical Navigation Camera – Wide angle (ONC-W1) on February 22, 2019 at an onboard time of around 07:30 JST. Credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST.

A computer graphic image by the Japan Aerospace Exploration Agency (JAXA) showing the Japanese unmanned spacecraft Hayabusa2 approaching the asteroid Ryugu. Credit: JAXA

Figure 1 was captured roughly 1 minute after touchdown at an estimated altitude of about 25m (error is a few meter). The colour of the region beneath the spacecraft’s shadow differs from the surroundings and has been discoloured 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 bullet (projectile). 

Figure 2 shows the same region as Figure 1 overlapped with the planned touchdown site. Since the touchdown site sits at the canter of the discoloured area, we believe that it was possible to touchdown at the expected place. However, an accurate touchdown point will be examined during a more detailed analysis in the future. Also shown in Figure 2 is the white target marker, which is shining in the reflected sunlight. 

Figure 2: Touchdown image overlapped with the planned touchdown site. The white dot at the end of the arrow is the target marker. Credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST.

For comparison, Figure 3 shows the previously captured image of the touchdown site. Figure 4 shows this same image but without any markings. Since this image was taken before dropping the target marker, the target marker is not visible in this picture. As you can see from Figures 3 and 4, there was no discoloured area on the asteroid surface around the touchdown point. 

Figure 3: Position of the planned touchdown site and target marker. The size of the circle at the planned site is 6m in diameter. X indicates the position that the target marker 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.

Figure 4: This is the same image as Figure 3, but without the markings. credit： JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu, AIST.

Source: JAXA