トピックスPhotographing the Earth just before Hayabusa2's swing-by

On December 3, 2015, Hayabusa2 drew near the Earth, ready to use the planet's gravity to adjust its orbital course towards Asteroid Ryugu (Earth swing-by). Just before the spacecraft's closest approach, its onboard Wide angle Optical Navigation Camera (ONC-W2) snapped a few photographs of our planet. Figure 1 shows six different pictures taken of the Earth side-by-side. In Figure 2, the images are combined as an animation that shows Hayabusa2's Earth approach.

  • Figure 1: Just before the swing-by on December 3, 2015, Hayausa2's ONC-W2 camera photographed the Earth. From left to right shows the time sequence of images taken at (in JST) 0900 (200, 000 km away from the centre of the Earth), 12:00 (150, 000 km away), 14:30 (100,000 km away), 16:00 (72,000 km away), 16:45 (57,000 km away) and 17:45 (36,000 km away).
    (©JAXA)
  • Figure 2: Animation of the ONC-W2 images taken between 09:00 and 17:45 (JST). The viewing angle is at about 60 degrees and the time shown on the image is in Universal Time (UT).
    (©JAXA)

When the first image in Figure 1 was taken (at 09:00 JST), the distance to the centre of the Earth was 200,000 km. By the last image (at 17:45 JST), the distance was just 36,000 km. A simulated image of the Earth corresponding to the photograph at 17:45 JST, is shown in Figure 3. The central region shows the Arabian Peninsula. The images from ONC-W2 itself are always in black and white.

  • Figure 3: Left shows the 17:45 photograph from the ONC-W2 camera. Right shows a simulated image from the same view point.
    The simulated image was created by using software of the FLOW project (https://darts.jaxa.jp/planet/tools/flow/) in DARTS (the Data ARchives and Transmission System) of the Center for Science-satellite Operation and Data Archive (C-SODA), ISAS/JAXA.
    (©JAXA)

※ ONC-W2 was developed by JAXA, The University of Tokyo, Chiba Institute of Technology, Rikkyo University, Meiji University, Nagoya University, The University of Aizu, and Kochi University.

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)