トピックスThe orbit for Hayabusa2's Earth swing-by
has been decided!

Hayabusa2 is set to swing-by the Earth on December 3rd, 2015. Two orbital correction manoeuvres (denoted TCM1 and TCM2) were performed back in November and the precise orbit for the swing-by was fixed.

The projected path of the Hayabusa2 swing-by on the Earth's surface is shown in Figure 1.

  • Figure 1: The projected path of Hayabusa2 during the Earth swing-by. White dots mark the ground points every hour. (The ground points mark the place where a line between Hayabusa2 and the Earth's centre cross the Earth's surface). The numbers written in the figure denote the hour on December 3rd, 2015 at Japanese standard time (JST). (©JAXA)

Hayabusa2's Earth ground track traces a complex-looking pattern on the Earth's surface, but this is actually due to the Earth's own rotation. The route is really a simple curve coming from the Arctic to the Antarctic region as shown in Figure 2. Each ground point marks where a line between Hayabusa2 and the Earth's centre intersects the Earth's surface. As the Earth rotates underneath the spacecraft, the complex twist on the map in Figure 1 is produced.

  • Figure 2: The orbit of Hayabusa2 around the Earth. (©JAXA)

Hayabusa2's closest approach to the Earth will be at about 3090 km above the Pacific, near Hawaii, on December 3rd, 2015 at 19:08:07 JST. The spacecraft will pass right over Japan around noon on the same day, at a distance of roughly 140,000 km.
The angular direction (azimuth, elevation) and distance of Hayabusa2 during December 3rd when looking from Usuda (Nagano Prefecture) is shown in the table below.

Table: The direction and altitude of Hayabusa2 when looking from Usuda on December 3rd, 2015.

Time (hour) Azimuth (deg) Elevation (deg) Distance (km)
0555.7487.195273,300
0662.83517.659254,400
0769.10728.796235,500
0874.80440.423216,700
0980.14852.399197,800
1085.40564.610179,100
1191.23376.955160,500
12131.16589.180142,000
13276.29078.338123,500
14282.76966.270105,100
15288.95354.64886,600
16295.87643.84567,720
17304.53234.66048,130
18318.40229.65227,060
1964.45623.3055,871
20148.787-44.67928,760
21156.381-50.02451,050
22155.122-49.90671,600
23152.246-47.28091,170
24150.164-43.071110,100

Note)When looking at the azimuth angle 0 is directly north, 90 is east, 180 is south and 270 is west. The elevation angle is the angle from the horizon, with 90 being directly overhead. The distance is the distance from Usuda, not the shortest distance from the Earth.

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)