Performance of Akatsuki/IR2 in Venus orbit: the first year

Earth, Planets and Space

Naru Hirata¹  Takeshi Imamura²  George L. Hashimoto³  Yasumasa Kasaba⁴  Kosuke Takami⁴  Ko-ichiro Sugiyama⁵  Tetsuya Fukuhara⁶  Hiroki Kashimura⁷  Munetaka Ueno⁷  Takayuki Enomoto⁸  Takeshi Horinouchi⁹  Hiroki Ando^1,10  Takashi Nakakushi^1,11  Yuri Sakurai^1,12  Kenta Sawai^1,12  Shin-ya Murakami^1,13  Masato Nakamura^1,13  Nobuaki Ishii^1,13  Yukio Yamamoto^1,13  Chikako Hirose^1,13  Takao M. Sato^1,13  Takumi Abe^1,13  Atsushi Yamazaki^1,13  Takehiko Satoh^1,13  Makoto Suzuki^1,13  Manabu Yamada^1,14  Shoko Ohtsuki^1,15  Kazunori Ogohara^1,16 

[1] ARC-Space, CAIST, The University of Aizu;Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University of Tokyo;Department of Earth Science, Okayama University;Department of Geophysics, Graduate School of Science, Tohoku University;Department of Information Engineering, National Institute of Technology, Matsue College;Department of Physics, Rikkyo University;Department of Planetology, Center for Planetary Science, Kobe University;FAST Corporation;Faculty of Environmental Earth Science, Hokkaido University;Faculty of Science, Kyoto Sangyo University;Faculty of Tourism, Wakayama University;Graduate School of Natural Science and Technology, Okayama University;Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency;Planetary Exploration Research Center, Chiba Institute of Technology;School of Commerce, Senshu University;School of Engineering, The University of Shiga Prefecture;

关键词: Venus;    Atmosphere;    Orbiter;    Akatsuki;    Near-infrared;    Window;   

DOI  :  10.1186/s40623-017-0736-x

来源: DOAJ

【 摘 要 】

Abstract The first year (December 2015 to November 2016) of IR2 after Akatsuki’s successful insertion to an elongated elliptical orbit around Venus is reported with performance evaluation and results of data acquisition. The single-stage Stirling-cycle cryo-cooler of IR2 has been operated with various driving voltages to achieve the best possible cooling under the given thermal environment. A total of 3091 images of Venus (1420 dayside images at 2.02 μm and 1671 night-side images at 1.735, 2.26, and 2.32 μm) were acquired in this period. Additionally, 159 images, including images of stars for calibration and dark images for the evaluation of noise levels, were captured. Low-frequency flat images (not available in pre-launch calibration data) have been constructed using the images of Venus acquired from near the pericenter to establish the procedure to correct for the IR2 flat-field response. It was noticed that multiple reflections of infrared light in the PtSi detector caused a weak but extended tail of the point-spread function (PSF), contaminating the night-side disk of Venus with light from the much brighter dayside crescent. This necessitated the construction of an empirical PSF to remove this contamination and also to improve the dayside data by deconvolution, and this work is also discussed. Detailed astrometry is performed on star-field images in the H-band (1.65 μm), hereby confirming that the geometrical distortion of IR2 images is negligible.

【 授权许可】

Unknown