To address NASA's need for L1 C/A-based navigation with better anti-spoofing ability and higher accuracy, Broadata Communications, Inc. (BCI) proposes to develop a new Navigation Robustness and Accuracy Improvement (NRAI) system, based on BCI's innovative noise nulling and observable combiner technology. BCI's novel approach incorporates the innovations of the highly successful multiple-antenna detection technique and the optimized fast quad diversity combiner technique, enabling BCI to meet NASA's requirements for reliability, safety, and high accuracy by effectively nullifying the interference noise from GPS receiver data and eliminating errors and ambiguities in observables. The NRAI system offers a 4-6 dB SNR improvement factor over current techniques and increases the accuracy of L1 C/A navigation to less than 1 m and 1 cm/s, which directly fulfills NASA's requirement of anti-spoofing ability and high accuracy. In Phase I BCI will demonstrate the feasibility of the NRAI system by building and testing a preliminary prototype, which will demonstrate TRL-level 3-4 by the end of Phase I. In Phase II, BCI plans to develop a fully functional prototype and demonstrate the anti-spoofing and high-accuracy navigation performance of NRAI. The demonstrated results will offer NASA capabilities of accurate and reliable navigation using L1 C/A code.