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In this paper, we present the single frequency PPP algorithms based on our GR models with applying CLAS(Centimeter Level Augmentation Service) data from Japan Quasi-Zenith-Satellite-System (QZSS), comparing with the positioning results applying the MADOCA (Multi-GNSS Advanced Demonstration tool for Orbit and Clock Analysis) Products which had been developed by JAXA (Japan Aerospace Exploration Agency) and are provided by GPAS (Global Positioning Augumentation Service Corporation), Throughout the numerical experiments the total 3DMMS error by applying CLAS is approximately 0.28 [m], in contrary with the total 3DMMS error by applying MADOCA Productsis being aproximately 0.52 [m].

We have developed a star sensor as an experimental device onboard the SERVIS-1 satellite launched in October 2003. The in-orbit data have verified its fundamental performance. One of the advantages of our star sensor is that the baffle has a small length of 120 mm instead of 182 mm in the conventional two-stage baffle design. The key concepts for light shielding are total internal reflection phenomena inside a nearly half sphere (NHS) lens and scattering light control by gloss black paint. However, undesirable background noise by the sun outside of the field of view (FOV) was observed in the corner of the FOV in the orbital experiment. Ray trace simulations revealed that slight scattering light on the specular baffle wall entered the NHS lens and reached the corner of the image sensor through the multi-reflection path inside the lens. It was found that the stray light path can be shielded effectively if the diameter of the aperture under the NHS lens was reduced. We redesigned the baffle and evaluated the light shielding ability with our sun interference test facility on the ground, and confirmed that the stray light was reduced below the acceptable level. As a result, the light shielding technique which we have proposed was proved to be effective for a small-size baffle. The redesigned star sensor is planned to be installed as a main attitude sensor for the SERVIS-2 satellite scheduled to be launched in February 2008.

We have developed Satellite controller Integrated with Star sensors (SIS) as a prototype of a future small and low-priced satellite controller. To reduce size and cost of the controller, SIS integrates attitude sensors into star sensors with medium resolution and medium sensitivity, adopts Commercial Off-The-Shelf (COTS) electrical parts for key parts such as CPU and CCD, and integrates several electronics for star identification, attitude determination, attitude control, and data handling into a single processing unit. Newly developed computer architecture is introduced for high reliability with COTS parts under the harsh space environment. In this paper, we will focus on the new star identification algorithm dedicated for star sensors with medium resolution and medium sensitivity and evaluate it with in-orbit experiment data of SIS.