Innovative Cryogenic System for Japanese Infrared Astronomical Mission "SPICA"
- Paper number
IAC-05-A3.1.06
- Author
Dr. Hiroyuki Sugita, Japan Aerospace Exploration Agency (ISTA/JAXA), Japan
- Coauthor
Dr. Hiroki Nagai, Tohoku University, Japan
- Coauthor
Prof. Takao Nakagawa, Japan Aerospace Exploration Agency (JAXA)/ISAS, Japan
- Coauthor
Prof. Toshio Matsumoto, Japan Aerospace Exploration Agency (JAXA)/ISAS, Japan
- Coauthor
Prof. Masahide Murakami, University of Tsukuba, Japan
- Coauthor
Mr. Katsuhiro Narasaki, Japan
- Coauthor
Mr. Masayuki Hirabayashi, Japan
- Year
2005
- Abstract
This paper describes the innovative cryogenic system for the SPICA mission. The proposed infrared mission of Japan will carry out astronomical observations with high sensitivity and resolution at the sun-earth L2 point in the 2010s. In this advanced cryogenic IR mission, since the large primary mirror of and focal plane instruments on the optical bench are cooled down to lower than 5 K for 5 years or longer, the innovative cooling concept is newly introduced that mechanical cryocoolers with effective radiant cooling are employed in place of short-lifetime cryogen such as LHe. First, radiant cooling structure of the spacecraft is investigated with thermal mathematical models. Some configurations of radiators, shields and solar-array paddles are discussed from points of view of technical feasibility and mission operation. Next, mechanical cryocoolers are discussed. The temperature of 4.5 K is obtained by the Joule-Thomson circuit combined with the 20K-class Stirling cryocooler. Based on the same JT cooler for the "JEM/SMILES" mission on the International Space Station, the 4K-class cooler has been modified and developed for higher reliability for 5 years and higher cooling capacity of more than 30 mW. Then, the development status of the 3He-JT circuit for the lowest temperature of 1.7 K is reported. Recent results of experiments give that the breadboard model of the 1K-class cryocooler successfully exceeds the required cooling capacity of 10 mW at 1.7 K with small power consumption. Since the 20K-class Stirling cryocooler is commonly used with the 4K-class and 1K-class coolers, reliability and cooling capacity should be improved for the mission accomplishment. Experimental results with optimized configuration of the cooler and new material for the regenerator are shown. Finally, the heat rejection system from those cryocoolers is noted.
- Abstract document
- Manuscript document
IAC-05-A3.1.06.pdf (🔒 authorized access only).
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