Abstract
Recently, scientific satellites and earth observation satellites have required more accurate pointing and higher angular rate maneuver capabilities. Autonomous attitude determination without a priori information has also became important, reflecting the need to simplify satellite systems and operations. To realize these requirements, we have been developing a precision autonomous star tracker for agile spacecraft, which is named the Next-Generation Star Tracker (NSTT). NSTT provides high-accuracy attitude determination results: random error is less than 4 arc seconds (3σ), while bias error is respectively less than 6 and 4 arc seconds (3σ) for wide and narrow temperature range. NSTT is able to track and acquire stars under high attitude-rate of 2 deg/s with 99.9% probability. A qualification model of NSTT has been manufactured and its functions and performances have been evaluated by qualification tests. NSTT is planned to be installed on the next X-ray observation satellite, ASTRO-H. This paper describes the technical challenges of NSTT and our solutions for them. This paper also presents the system design, manufacturing results and some test results of NSTT.
