Development and in-flight calibration of IR2: 2-μm camera onboard Japan's Venus orbiter, Akatsuki 7. Planetary science

Takehiko Satoh, Masato Nakamura, Munetaka Ueno, Kazunori Uemizu, Makoto Suzuki, Takeshi Imamura, Yasumasa Kasaba, Seiji Yoshida, Masafumi Kimata

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


IR2, a near-infrared camera in the 2-μm region onboard Akatsuki has been developed to primarily study the middle-to-lower atmospheric dynamics of Venus as probed in the 1.74- and 2.3-μm "windows" of the CO2 CO2 atmosphere on the night side. The spatial and temporal variability of CO below the clouds is also studied by differentiating 2.32-μm CO-band images from simultaneous 2.26-μm images. Images of the night-side disk in these wavelengths will enable us to determine the zonal and meridional winds near the cloud-base altitudes. IR2 also images at 2.02 μm, the center of a CO2CO2 absorption band. Such images can visualize the variation of the cloud-top altitudes as contrast features due to different absorption path lengths of the reflected sunlight. Tracking of the 2.02-μm features will also enable us to obtain wind information at the cloud-top level. Together with the other cameras and the radio science equipment on Akatsuki, IR2 will contribute to understanding of the production and maintenance mechanism of super-rotation in the Venusian atmosphere. During cruise, IR2 observed zodiacal light with a broad-band H filter (1.65 μm), imaged the Earth-moon remotely from a distance of ~30 million km, and determined Venus's phase curves at small phase angles. We have just started the early phase operation check of IR2 at Venus, as the orbit insertion in December 2015 was successful.

Original languageEnglish
Article number74
Journalearth, planets and space
Issue number1
Publication statusPublished - 2016 Dec 1


  • Atmosphere
  • Atmospheric windows
  • Clouds
  • Dynamics
  • Imaging camera
  • Near-infrared
  • Venus
  • Zodiacal light

ASJC Scopus subject areas

  • Geology
  • Space and Planetary Science


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