*Tomoko Arai1, Masanori Kobayashi1, Hiroki Senshu1, Koji Wada1, Ko Ishibashi1, Toshihiro Kasuga1, Manabu Yamada1, Shingo Kameda13, Katsuhito Ohtsuka3, Jun-ichi Watanabe2, Takashi Ito2, Yasuhiro Kawakatsu4, Sarli Bruno4, Takahiro Iwata4, Tatsuaki Okada4, Makoto Yoshikawa4, Tomoki Nakamura6, Hikaru Yabuta5, Sho Sasaki5, Mutsumi Komatsu7, Aiko Nakato4, Takahiro Hiroi8, Takashi Mikouchi9, Seitaro Urakawa10, Shinsuke Abe11, MASATERU ISHIGURO12, Hiroshi Kimura14, Shogo Tachibana15, Ryosuke Nakamura16, Keiko Nakamura-Messenger17, Mikiya Sato20, Ralf Srama18, Harald Kruger19
(1.Planetary Exploration Research Center, Chiba Institute of Technology, 2.National Astronomical Observatory of Japan, 3.Tokyo Meteor Network, 4.JAXA, 5.Osaka University, 6.Tohoku University, 7.Sokendai, 8.Brown University, 9.The University of Tokyo, 10.Japan Spaceguard Association, 11.Nihon University, 12.Seoul National University, 13.Rikkyo University, 14.Kobe University, 15.Hokkaido University, 16.AIST, 17.NASA Johnson Space Center, 18.University of Stuttgart, 19.Max Planck Institutes, 20.Kawasaki Municipal Science Museum)
Keywords:Asteroid (3200) Phaethon, Meteor Showers, Meteor shower parent bodies, Primitive bodies, DESTINY+, PROCYON-mini
Asteroid (3200) Phaethon is a parent body of the Geminids meteor shower. While most of the parent bodies of meteor showers are comets, cometary activity of Phaethon has only been reported near its perihelion at 0.14 AU. Phaethon is likely a comet to asteroid transitional body. Na depletion is reported from visible spectroscopic study of the ground observation of the Geminids meteoroid. Since an expected temperature by solar heating at 0.14 AU is not high enough to sublimate Na from Na-bearing phases, the observed Na depletion is likely derived from surface materials of the parent Phaethon. Na depletion does not occur in chondritic materials, but does occur in differentiated chondrites, such as primitive achondrites, which are subject to melting and segregation of Na-rich silicate melts. Phaethon may hold a signature of comet-asteroid transition body and primitive-differentiated material. Because of its small perihelion distance, dehydration of the surface material by solar heating is expected, but some primitive, hydrous material may still reside in its interior. Phaethon is an ideal body to understand on-going thermal evolution of primitive bodies in the solar system. Further, Phaethon is among the largest potentially hazardous asteroids (PHAs), of which cross the Earth's orbit. Thus, Phaethon is a critical mission target both in the context of science and planetary defense. Here, we present a flyby mission to Phaethon and its related asteroids by the DESTINY+mother ship and its daugther probe "PROCYON-mini", with their scientific significance.