Flight Performance of the AKARI Cryogenic System
Abstract
We describe the flight performance of the cryogenic system of the infrared astronomical satellite AKARI, which was successfully launched on 2006 February 21 (UT). AKARI carries a 68.5 cm telescope together with two focal plane instruments, Infrared Cameras (IRC) and Far Infrared Surveyor (FIS), all of which are cooled down to cryogenic temperature to achieve superior sensitivity. The AKARI cryogenic system is a unique hybrid system, which consists of cryogen (liquid helium) and mechanical coolers (2-stage Stirling coolers). With the help of the mechanical coolers, 179 L (26.0 kg) of super-fluid liquid helium can keep the instruments cryogenically cooled for more than 500 days. The on-orbit performance of the AKARI cryogenics is consistent with the design and pre-flight test, and the boil-off gas flow rate is as small as 0.32 mg/s. We observed the increase of the major axis of the AKARI orbit, which can be explained by the thrust due to thermal pressure of vented helium gas.
Cite
@article{arxiv.0708.1797,
title = {Flight Performance of the AKARI Cryogenic System},
author = {Takao Nakagawa and Keigo Enya and Masayuki Hirabayashi and Hidehiro Kaneda and Tsuneo Kii and Yoshiyuki Kimura and Toshio Matsumoto and Hiroshi Murakami and Masahide Murakami and Katsuhiro Narasaki and Masanao Narita and Akira Ohnishi and Shoji Tsunematsu and Seiji Yoshida},
journal= {arXiv preprint arXiv:0708.1797},
year = {2015}
}
Comments
19 pages, 10 figures, and 6 tables. Accepted for publication in the AKARI special issue of the Publications of the Astronomical Society of Japan