Relative Dynamics Inc. will develop an Optical Communication Array Transceiver (OCAT) with capabilities required in NASA Subtopic H9.01: Long-Range Optical Communication. Telescope arrays have advantages of lesser cost, improved diffraction-limited performance, slighter gravitational effects, scalability, ease of maintenance, and redundancy in operations. In addition, the use of multiple apertures adds additional benefits such as the ability to mitigate atmospheric fading with spatial diversity, to use small aperture size to reduce or eliminate AO complexity, to increment ground station collection area over time, to reduce cost, to remove a single point of failure, and to enable support for simultaneous communications links by federating the array to multiple targets. Our technical objective is to analyze and develop a monostatic duplex (transmit and receive) coherent transceiver array with new commercial coherent integrated photonics modems and mass production composite-structure telescope array elements. The innovations in OCAT are for both spaceflight and ground systems and the array concepts can selectivity be applied to coherent and direct detection systems.
Our innovative Koester’s prism precision wave-front and angular sensor enables closed-loop control of (1) transmitter collimation (receiver focus) and (2) fine-pointing. The prism sensor samples the edge of the beam.
Carbon fiber composites have high stiffness, high tensile strength, low weight, high chemical resistance, high temperature tolerance and low thermal expansion. Continuous-carbon-fiber rivals beryllium in the key parameters of specific stiffness, and both transient and steady state thermal stability due to its much lower coefficient of thermal expansion (CTE). Our high-strength-to-weight ratio continuous carbon fiber structures will be manufactured by a world-leader composites manufacturer that is leveraging a multi-million dollar 5-year DARPA-sponsored automated manufacturing project.
Scalable versions of the innovations in the Optical Communication Array Transceiver (OCAT) will enable future data volume returns to and from space missions in multiple domains with return data rate (up to 100 Gbps) and distance (up to planetary) trade-offs. The innovations in OCAT are for both spaceflight and ground systems and will also enable navigation services (ranging, Doppler, and pointing knowledge) for NASA missions. Optical ground terminals are much smaller than RF ground terminals for a given data rate and data volume capability.
SpaceX, Google, Facebook, Amazon, Airbus and other large companies are pursuing High Altitude Platforms and very large (thousands) LEO satellite constellations for global internet deployment. This is a key commercial market for low-cost high-data-rate optical communication terminals. The monthly data for video is expected to increase to 38.1 million TB by 2021 from 4.4 million TB in 2016.