A self contained Precision Attitude Determination and Control System (PADACS) for CubeSats and Nanosats is proposed. The PADACS enables future CubeSat missions with precision fine pointing (0.1a) and dynamic slewing as will be required for imaging operations of ground targets. The PADACS incorporates a flight control computer, 2 Star Trackers, 3 axis reaction wheels and 3 axis electromagnets in a 4" x 4" x 3" (3/4U) CubeSat sized module which is compatible with the P-POD launch dispenser. The system is based on the highly successful IMI-100 miniADACS and extends its performance capability to the 0.1deg range by incorporation of 2 star cameras and attitude determination software. The system is thus responsive to the solicitation requirement of novel modification endeavors to existing COTS components. A program for development of the cameras, electronics, and processing software is outlined. The technology is significant because it extends the capability of current low cost Nanosats to tactical imaging and other missions requiring fine pointing and dynamic retargeting, missions hitherto restricted to $100M spacecraft. The new PADACS will facilitate rapid development of low cost satellites by providing a turnkey system which would be capable of determining and controlling spacecraft attitude automatically; speeding integration and simplifying operations.
Benefit: We developed the IMI-100 miniature ADACS for CubeSats as a DARPA SBIR. This system has enabled a number of nanosatellite applications not previously possible including the NRO requirement Colony I. The performance of the IMI-100 is currently limited by the Sun sensor and magnetometer attitude determination which gives end-to-end accuracy of >1deg, limited to periods of Sun visibility. Addition of the star trackers will yield day/night accuracy of 0.1 deg which will enable many new nanosatellite applications requiring the next level of precision fine pointing such as tactical Earth imaging and Sun, planetary and deep space science. We have been very successful in commercializing the small ADACS by having sold more than 18 systems in less than one year. Improvement of system performance by an order of magnitude will open many new DoD and commercial markets.
Keywords: Cubesat, Nanosat, Miniadacs, Attitude Determination And Control System, Star Tracker, Imi-100.
