ESA GNC Conference Papers Repository
Precision Autonomous Star Tracker for Agile Spacecraft
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 missions, we have been developing a precision autonomous star tracker for agile spacecraft, which is named as the Next-Generation Star Tracker (NSTT). NSTT provides high-accuracy attitude determination results: random error is less than 4 arc seconds (3sigma), while bias error is respectively less than 6 and 4 arc seconds (3sigma) for wide and narrow temperature range. NSTT is able to track and acquire stars under high attitude-rate of 2deg/s with 99.9% probability. A qualification model of NSTT has been manufactured and its functions and performances have been evaluated by pre-qualification tests. The formal qualification tests of NSTT will be completed in September 2011. We plan to install NSTT on the Super Low Altitude Test Satellite, SLATS, for an in-orbit experiment in 2013 and on the next X-ray observation satellite, ASTRO-H, for attitude control, in 2014.This paper first describes the technical challenges of NSTT and our solutions for them, and then summarizes the functions and performances of NSTT. This paper also presents the manufacturing results and some test results of NSTT.