TY - JOUR
T1 - Ultraviolet imager on Venus orbiter Akatsuki and its initial results
AU - Yamazaki, Atsushi
AU - Yamada, Manabu
AU - Lee, Yeon Joo
AU - Watanabe, Shigeto
AU - Horinouchi, Takeshi
AU - Murakami, Shin ya
AU - Kouyama, Toru
AU - Ogohara, Kazunori
AU - Imamura, Takeshi
AU - Sato, Takao M.
AU - Yamamoto, Yukio
AU - Fukuhara, Tetsuya
AU - Ando, Hiroki
AU - Sugiyama, Ko ichiro
AU - Takagi, Seiko
AU - Kashimura, Hiroki
AU - Ohtsuki, Shoko
AU - Hirata, Naru
AU - Hashimoto, George L.
AU - Suzuki, Makoto
AU - Hirose, Chikako
AU - Ueno, Munetaka
AU - Satoh, Takehiko
AU - Abe, Takumi
AU - Ishii, Nobuaki
AU - Nakamura, Masato
N1 - Funding Information:
The authors are grateful to all the members of the UVI instrument team for their excellent support and effort in completing UVI, especially NEC corpora‑ tion, NEC Space Technologies, Ltd., Nikon Corporation, FUJITOK Corporation, Tamagawa Seiki Co., Ltd., and Cornes Technologies. The authors are also grateful to all the members of the Akatsuki/VCO project team for their remark‑ able support in developing the Akatsuki spacecraft. The authors appreciate to Drs. Markiewicz, W. J., Keller, H. U., and Titov, D. V. for their kind and helpful implications and suggestions about the design of UVI. The authors also thank to the members of the optical facility in Earth Observation Research Center (EORC) of JAXA and the National Astronomical Observatory of Japan (NAOJ) for the ground‑based calibration experiments before the launch. IUE UV star spectra were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA Contract NAS5‑26555. Support for MAST for non‑HST data is provided by the NASA Office of Space Science via Grant NNX09AF08G and by other grants and contracts.
Publisher Copyright:
© 2018, The Author(s).
PY - 2018/12/1
Y1 - 2018/12/1
N2 - The ultraviolet imager (UVI) has been developed for the Akatsuki spacecraft (Venus Climate Orbiter mission). The UVI takes ultraviolet (UV) images of the solar radiation reflected by the Venusian clouds with narrow bandpass filters centered at the 283 and 365 nm wavelengths. There are absorption bands of SO2 and unknown absorbers in these wavelength regions. The UV images provide the spatial distribution of SO2 and the unknown absorber around cloud top altitudes. The images also allow us to understand the cloud top morphologies and haze properties. Nominal sequential images with 2-h intervals are used to understand the dynamics of the Venusian atmosphere by estimating the wind vectors at the cloud top altitude, as well as the mass transportation of UV absorbers. The UVI is equipped with off-axial catadioptric optics, two bandpass filters, a diffuser installed in a filter wheel moving with a step motor, and a high sensitivity charge-coupled device with UV coating. The UVI images have spatial resolutions ranging from 200 m to 86 km at sub-spacecraft points. The UVI has been kept in good condition during the extended interplanetary cruise by carefully designed operations that have maintained its temperature maintenance and avoided solar radiation damage. The images have signal-to-noise ratios of over 100 after onboard desmear processing. [Figure not available: see fulltext.].
AB - The ultraviolet imager (UVI) has been developed for the Akatsuki spacecraft (Venus Climate Orbiter mission). The UVI takes ultraviolet (UV) images of the solar radiation reflected by the Venusian clouds with narrow bandpass filters centered at the 283 and 365 nm wavelengths. There are absorption bands of SO2 and unknown absorbers in these wavelength regions. The UV images provide the spatial distribution of SO2 and the unknown absorber around cloud top altitudes. The images also allow us to understand the cloud top morphologies and haze properties. Nominal sequential images with 2-h intervals are used to understand the dynamics of the Venusian atmosphere by estimating the wind vectors at the cloud top altitude, as well as the mass transportation of UV absorbers. The UVI is equipped with off-axial catadioptric optics, two bandpass filters, a diffuser installed in a filter wheel moving with a step motor, and a high sensitivity charge-coupled device with UV coating. The UVI images have spatial resolutions ranging from 200 m to 86 km at sub-spacecraft points. The UVI has been kept in good condition during the extended interplanetary cruise by carefully designed operations that have maintained its temperature maintenance and avoided solar radiation damage. The images have signal-to-noise ratios of over 100 after onboard desmear processing. [Figure not available: see fulltext.].
KW - Initial results of cloud tracking
KW - UV images of Venus at the cloud top altitude
KW - UVI performance
KW - Ultraviolet imager (UVI)
KW - Venus orbiter Akatsuki
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U2 - 10.1186/s40623-017-0772-6
DO - 10.1186/s40623-017-0772-6
M3 - Article
AN - SCOPUS:85041931056
SN - 1880-5981
VL - 70
JO - Earth, Planets and Space
JF - Earth, Planets and Space
IS - 1
M1 - 23
ER -
