TopicsRyugu seen from a distance of 1500km

Hayabusa2 is continuing to approach asteroid Ryugu using optical navigation. Figure 1 shows Ryugu photographed by the ONC-T (Optical Navigation Camera - Telescopic) on June 10, 2018, from a distance of about 1500km. The celestial body shining brightly in the center of the image is Ryugu. Compared with images taken on June 6, the position in the sky (relative to background stars) where Ryugu is visible has changed. The astronomical magnitude of Ryugu is now -5.7 mag.


  • (Large image) Figure 1. asteroid Ryugu imaged using the ONC-T. The photograph was taken on June 10, around 12:50 JST. The field of view is 6.3 degrees x 6.3 degrees and the exposure time is 178 seconds. From the spacecraft, you can see Ryugu in the direction of the constellation, Gemini (Gem).
    Ground observation team: JAXA, Kyoto University, Japan Spaceguard Association, Seoul National University.
    ONC team: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu and AIST.

Figure 2 shows a photograph taken at approximately the same time but using an exposure of about 0.09 seconds. Here, only Ryugu is imaged as a point and the background stars are now too faint to be seen. In expanding the section of image that contains Ryugu, the asteroid can be seen to have a diameter of about 5 or 6 pixels but this is still not sufficient to see the shape. However, from this image is does seem that Ryugu is not elongated like Itokawa.


  • (Large image) Figure 2: Ryugu imaged with the ONC-T. The photograph was taken on June 10, around 12:50 JST. The field of view is 6.3 degrees x 6.3 degrees and the exposure time is about 0.09 seconds.
    Ground observation team: JAXA, Kyoto University, Japan Spaceguard Association, Seoul National University.
    ONC team: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, University of Aizu and AIST.

Hayabusa2 will continue to draw closer to Ryugu. Please keep following us for future images!

Note:
Does it seem strange that in the caption of the ONC images we refer to the "ground observation team"? Primarily before the launch of the spacecraft, the ground observation team observed Ryugu (which was then referred to as 1999 JU3) and other potential celestial bodies using ground-based telescopes. The team were responsible for providing important data for selecting prospective candidates for the Hayabusa2 mission. After Ryugu was selected as the destination for Hayabusa2, the team observed Ryugu (to get light curve and spectrum observation data) and used this to investigate the physical properties of the asteroid.

The images from ONC are now being used by the ground observation team to accurately measure the position of Ryugu based on the location of the background stars in the captured image. In addition, they also create images for the public that we can all see. Members of the ground observation team are led by Principal Investigator, Professor Masateru Ishiguro at Seoul National University and consist of about 30 researchers from many domestic and international organizations. In addition to Professor Ishiguro, Dr. Daisuke Kuroda from Kyoto University and Drs Shin-ichiro Okumura and Seitaro Urakawa from the Japan Spaceguard Association work on the ONC image analysis.

Hayabusa2 project
2018.06.11

Message from Project 一覧

「はやぶさ2」は,人類が訪れたことのない小惑星「リュウグウ」との往復航行をする宇宙船です.どんな冒険が待ち受けているか誰にも分からないけれど,きっと面白い航海になるはずです。どんな旅をするか,楽しみにしていてください。
(プロジェクトマネージャ 津田雄一)