Microcosm, with Space Micro., and HRP Systems will design a plug-and-play (PnP) star sensor for small satellites. All three companies are well experienced in developing PnP systems for the U. S. Air Force during the past 6 years. On an existing Phase II Air Force SBIR program, Microcosm built a prototype star sensor called MicroMak. The sensor proposed here will focus on PnP compatibility for NASA missions of interest. The PnP star sensor recurring cost target is $150 K to $200 K, with a mass between 0.5 and 1 kg. Expected NASA mission applications necessitate a modified version of the baseline MicroMak sensor, including: 1) Interfaces compatible with a new PnP avionics architecture, 2) radiation-hardened focal plane arrays (FPAs) and processing electronics to enable longer mission life. The baseline MicroMak sensor was designed with inherent radiation-tolerant features: complimentary metal oxide semiconductor (CMOS) FPAs with no direct space view, and all-reflective optical elements. The new PnP star sensor will build on MicroMak heritage and provide a modular, PnP-compatible, long-life star sensor for NASA missions, at low cost compared with traditional star sensors. A cost and mass reduction of a factor of 2 or more over traditional sensors is expected.