はやぶさ２、次の探査先決定　高速自転小惑星へ、１１年の旅―ＪＡＸＡ

　宇宙航空研究開発機構（ＪＡＸＡ）は１５日、探査機「はやぶさ２」が小惑星「りゅうぐう」で採取した砂が入ったとみられるカプセルを地球に帰還させた後の新たな探査先として、小惑星「１９９８ＫＹ２６」に向かうことが決まったと発表した。途中、別の小惑星の近くを通過しながら観測するなどし、２０３１年７月の到着を目指す。
　１９９８ＫＹ２６は地球と火星の間を回る小惑星。直径約３０メートルとりゅうぐう（同９００メートル）よりはるかに小さく、自転周期も約１０分と、りゅうぐう（約７時間）より高速で自転している。
　ＪＡＸＡによると、直径１００メートル以下の天体への接近観測は世界初。りゅうぐうとの比較で新たな知見が得られるほか、地球に衝突する恐れのある天体の構造解明にも役立つという。（2020/09/15-18:34）

The Hayabusa2 unmanned probe will explore the asteroid 1998KY26 after completing its current mission of delivering a capsule believed to be containing samples of sand from the asteroid Ryugu to Earth, the Japan Aerospace Exploration Agency, or JAXA, said Tuesday.
   The Japanese asteroid probe is expected to reach 1998KY26, which is traveling between Earth and Mars, in July 2031. The asteroid is only about 30 meters in diameter, smaller than some 900 meters of Ryugu, and rotates about every 10 minutes, compared with about seven hours for Ryugu.
   According to JAXA, it will be the first close-up observations of an asteroid with a diameter of less than 100 meters. Comparison between data from Ryugu and 1998KY26 is expected to offer new discoveries and help researchers understand the structure of Earth-crossing celestial bodies.
   After dropping the capsule on Earth in December this year, Hayabusa2 will perform a swing-by using Earth's gravity to head for 1998KY26 for its next mission. On its way to 1998KY26, Hayabusa2 will observe another asteroid, 2001CC21, while traveling close to it in July 2026. The spacecraft will conduct a swing-by two more times, in December 2027 and June 2028, before reaching 1998KY26.
   Hayabusa2 will conduct observations of 1998KY26 from above its surface. It may also try landing on it.