University of Tokyo's Pico-Satellite Project "PRISM"

Paper number

IAC-05-B5.4.09

Author

Mr. Masaki Nagai, University of Tokyo, Japan

Coauthor

Mr. Takashi Eishima, University of Tokyo, Japan

Coauthor

Mr. Akito Enokuchi, University of Tokyo, Japan

Coauthor

Mr. Tsukasa Funane, University of Tokyo, Japan

Coauthor

Dr. Ryu Funase, Japan Aerospace Exploration Agency (JAXA), Japan

Coauthor

Dr. Yuya Nakamura, University of Tokyo, Japan

Coauthor

Prof. Shinichi Nakasuka, University of Tokyo, Japan

Coauthor

Mr. Yuta Nojiri, University of Tokyo, Japan

Coauthor

Mr. Fumiki Sasaki, University of Tokyo, Japan

Year

2005

Abstract

This paper presents our design concept and some technological topics in our ongoing project “PRISM”, which stands for “Pico-satellite for Remote-sensing and Innovative Space Missions”. We have been designing and developing this pico-satellite since 2002. Its main mission is remote sensing. Basically, we aim to obtain Earth images with as high resolution as about 30 meters by its compact spacecraft bus, which is a 17cm*17cm*25cm and weighs less than 5kg. 

In order to acquire this high-resolution images, enough focal length and large aperture are required. Many of conventional small remote sensing satellites have achieved this high resolution with multiple lenses or mirrors by obtaining enough light path length within the limited satellite size. However the multiple lens/mirror system requires severe stiffness to keep the precisely designed optical system unchanged even after experiencing the launch environment, which requires manufacturing cost and structure mass. Moreover, we cannnot mount such optical divices that occupy most of the room inside the satellite. 

PRISM optics system employs a totally different concept in order to solve this problem. PRISM deploys an extensible boom up to 800mm after the separation from the launching vehicle. The boom has a lens on its end, and it works as a structure of telescope. We have developed special extensible boom for this objective, using GFRP both for high elasticity and for the prevention of RF interference. The deployed boom lengthens the distance between a lens and an image sensor, which can realize the desired focal length within such a nano-scaled satellite.  
Additional technological issues occur if we employ this concept, such as how to keep focusing at the focal plane, and how to avoid the stray light coming into the optics. We have developed a kind of “auto-focus” system suitable for nano-satellite size, and light shade to be implemented on this extensible boom. 

 The other fundamentals of its bus technologies are on the basis of the experience in our previous project, “CubeSat XI”, which was launched in 2003 and has been operative for more than 20 months. We are now developing PRISM engineering model with a hope to launch its flight model in 2006.

Abstract document

IAC-05-B5.4.09.pdf

Manuscript document

IAC-05-B5.4.09.pdf (🔒 authorized access only).

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