Geolocation and Attitude Determination from Laser Communication Systems

In order to realize the geolocation and attitude determination benefits of formation flying multi-spacecraft clusters or constellations with onboard Acquisition, Tracking and Pointing (ATP) lasercom systems, four key elements must be present: 1. Broadband inter-spacecraft communications to enable the transport of high resolution pointing sensor data around the topology to the computing node(s) and return geolocation and attitude information to the individual nodes. 2. Precision inter-spacecraft timing synchronization to enable accurate time stamping of multi-sensor data samples throughout the formation. 3. Precision inter-spacecraft relative range measured by cooperative time-of-flight (TOF) handshake. 4. Precision pointing sensor data to enable accurate relative pointing angle determination between each craft and its nearest neighbors. An inter-spacecraft laser communications network is the only integrated subsystem that can provide all four of these key elements [26]. The proposed SBIR Phase II effort will leverage several existing SPI programs (Section 4) to extend the models, analyses and designs from the Phase I effort, and produce a fully-functional prototype at a minimum cost. Space Photonics (SPI) will develop the algorithms, calibration processes, and software/firmware for the inter-spacecraft ranging, timing synchronization, attitude and position determination; and, will demonstrate these functions in our free space optical, lasercom testbed (LaserFire® testbed). However, the algorithms, calibration processes, and software/firmware developed for this SBIR Phase II program can be applied to any gimbaled or gimbal-less lasercom crosslink system. These functions can even be applied to RF crosslink systems. But the RF implementation will suffer significant loss of inter-spacecraft position accuracy due to the larger RF beamwidths.