Optical Physics Company (OPC) proposes to develop a high accuracy version of its interferometric star tracker capable of meeting the milli-arcsecond-level pointing requirements. Such high accuracy tracker can be used for precision pointing of the large telescope, and can permit open-loop pointing of narrow-beam laser signals. The latter can enable deep-space lasercom missions without the technical and operational complexity of a ground based beacon. OPC has already built multiple versions of this star tracker for several applications for various DoD customers. Current technical maturity of the star tracker is TRL 5- which is expected to advance to TRL 6 during the proposed Phase I project due to space readiness and flight tests under parallel efforts. During the proposed Phase I effort, OPC will first develop requirements. This will be followed by design trades and formulation of a detailed design. Phase I will conclude with a Preliminary Design Review (PDR). During Phase II, the design will be advanced to the Critical Design Review (CDR) level and a prototype will be built and tested. Given that the existing baseline designs for OPC's visible and SWIR band interferometric star trackers are at TRL 5, OPC has a head start.