Initial performance of the radio occultation experiment in the Venus orbiter mission Akatsuki Akatsuki at Venus: The First Year of Scientific Operation Masato Nakamura, Dmitri Titov, Kevin McGouldrick, Pierre Drossart, Jean-Loup Bertaux and Huixin Liu 7. Planetary science

Takeshi Imamura, Hiroki Ando, Silvia Tellmann, Martin Pätzold, Bernd Häusler, Atsushi Yamazaki, Takao M. Sato, Katsuyuki Noguchi, Yoshifumi Futaana, Janusz Oschlisniok, Sanjay Limaye, R. K. Choudhary, Yasuhiro Murata, Hiroshi Takeuchi, Chikako Hirose, Tsutomu Ichikawa, Tomoaki Toda, Atsushi Tomiki, Takumi Abe, Zen Ichi YamamotoHirotomo Noda, Takahiro Iwata, Shin Ya Murakami, Takehiko Satoh, Tetsuya Fukuhara, Kazunori Ogohara, Ko Ichiro Sugiyama, Hiroki Kashimura, Shoko Ohtsuki, Seiko Takagi, Yukio Yamamoto, Naru Hirata, George L. Hashimoto, Manabu Yamada, Makoto Suzuki, Nobuaki Ishii, Tomoko Hayashiyama, Yeon Joo Lee, Masato Nakamura

Research output: Contribution to journalReview article

16 Citations (Scopus)

Abstract

After the arrival of Akatsuki spacecraft of Japan Aerospace Exploration Agency at Venus in December 2015, the radio occultation experiment, termed RS (Radio Science), obtained 19 vertical profiles of the Venusian atmosphere by April 2017. An onboard ultra-stable oscillator is used to generate stable X-band downlink signals needed for the experiment. The quantities to be retrieved are the atmospheric pressure, the temperature, the sulfuric acid vapor mixing ratio, and the electron density. Temperature profiles were successfully obtained down to ~ 38 km altitude and show distinct atmospheric structures depending on the altitude. The overall structure is close to the previous observations, suggesting a remarkable stability of the thermal structure. Local time-dependent features are seen within and above the clouds, which is located around 48-70 km altitude. The H2SO4 vapor density roughly follows the saturation curve at cloud heights, suggesting equilibrium with cloud particles. The ionospheric electron density profiles are also successfully retrieved, showing distinct local time dependence. Akatsuki RS mainly probes the low and middle latitude regions thanks to the near-equatorial orbit in contrast to the previous radio occultation experiments using polar orbiters. Studies based on combined analyses of RS and optical imaging data are ongoing.[Figure not available: see fulltext.]

Original languageEnglish
Article number137
JournalEarth, Planets and Space
Volume69
Issue number1
DOIs
Publication statusPublished - Dec 1 2017

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Keywords

  • Akatsuki
  • Radio occultation
  • Venus

ASJC Scopus subject areas

  • Geology
  • Space and Planetary Science

Cite this

Imamura, T., Ando, H., Tellmann, S., Pätzold, M., Häusler, B., Yamazaki, A., Sato, T. M., Noguchi, K., Futaana, Y., Oschlisniok, J., Limaye, S., Choudhary, R. K., Murata, Y., Takeuchi, H., Hirose, C., Ichikawa, T., Toda, T., Tomiki, A., Abe, T., ... Nakamura, M. (2017). Initial performance of the radio occultation experiment in the Venus orbiter mission Akatsuki Akatsuki at Venus: The First Year of Scientific Operation Masato Nakamura, Dmitri Titov, Kevin McGouldrick, Pierre Drossart, Jean-Loup Bertaux and Huixin Liu 7. Planetary science. Earth, Planets and Space, 69(1), [137]. https://doi.org/10.1186/s40623-017-0722-3