Description: CrossTrac Engineering, in cooperation with its subcontractors Dr. Suneel Sheikh of ASTER Labs, Inc, and Mr. Paul Graven of Cateni, Inc., proposes to develop a next generation star tracker capable of measuring the attitude of a spacecraft with mill-arcsecond accuracy. This unprecedented improvement in star tracker accuracy is achieved by tracking a single, bright guide star in the deep ultraviolet to soft x-ray bands (1 eV to 10 keV) using a differential measurement of guide star offset angle. The overall field-of-view of the Milli-arcsecond X-ray Star Tracker (MXST) will be limited to a fraction of a degree square with the highest accuracies achieved when the guide star is aligned with the star tracker boresight. This allows a simple, differential measurement to be made of the guide star location relative to the spacecraft coordinate system. By observing guide stars at high energy (short wavelength), the compact star tracker can achieve diffraction limited performance of one milli-arcsecond in a small, compact package.

Benefits: The MXST will provide an unprecedented precision attitude reference for new NASA missions. This novel instrument will enable new missions by providing milli-arcsecond level attitude knowledge for applications such as: ¿ Missions using clusters of spacecraft to create long baseline, sparse array apertures for probing the universe with increasingly high spatial resolution. The spacecraft in these clusters will require extremely accurate pointing control to the target of interest. ¿ Planetary missions using laser communications where precise pointing of the laser beam over long distances is necessary ¿ Extra-solar planet finder missions where ultra-precise position knowledge and stability are required, particularly where a coronograph is employed. ¿ Space Weather Missions ¿ Planetary Mapping and Observing Missions

We anticipate customers in the Department of Defense being interested in this technology for use on precision pointed platforms for intersatellite optical communication, earth observing systems and precision spacecraft navigation for on-orbit rendezvous. In particular, this instrument will be useful for missions attempting "Distributed RF Communications" whereby several spacecraft in a cluster emit precisely timed and synchronized RF signals to establish and control the positions of nulls and peaks in the RF energy at specific points on the Earth's surface.