Proliferated Low Earth Orbit Positioning, Navigation, and Timing

Across the Department of Defense, efforts are underway to develop robust alternatives to GPS for positioning, navigation, and timing (PNT). Caliola is developing one such GPS alternative for the Navy. Our Satellite Communications [SATCOM] Antenna Pointing for Positioning (SCAPP) solution leverages the pointing vectors produced by the Navy Multiband Terminal while tracking a satellite in geosynchronous (GEO) orbit. A key lesson learned from developing SCAPP is that uncertainty in satellite ephemeris is the dominant error source for positioning from SATCOM signals of opportunity. Proliferated low Earth orbit (pLEO) constellations offer a far more diverse and robust set of signals from which to calculate a PNT solution than GEO constellations. It is much more challenging to mount an anti-satellite attack against an entire constellation spanning hundreds or thousands of satellites. However, three design challenges make a pLEO GPS-denied PNT system more challenging than its GEO-based counterpart: maintaining (1) frequency and (2) time stability of the satellite clocks across a massive constellation, and (3) acquiring and predicting accurate orbits for hundreds or thousands of satellites. In this SBIR, Caliola and Advanced Space will architect and design an alternate PNT system that interfaces with the Navy’s GPS-based PNT Service (GPNTS) system. To address the aforementioned design challenges, our proposed architecture will build on Caliola’s SCAPP solution and on Advanced Space’s experience developing positioning and navigation solutions for cislunar space.