Ka-Band Telemetry Operations Concept: A Statistical Approach

Future NASA missions such as the Lunar Reconnaissance Orbiter, Kepler, James Webb Space Telescope, and Space Interferometry Mission will use Ka-band frequencies (26.5- and 32-GHz bands) for their primary science downlink instead of X-band frequencies (8.42-GHz band) due to scarcity of spectrum at X-band. At Ka-band frequencies, adverse weather events degrade the telemetry link performance to a greater degree than they do at X-band. The uncertainty about the weather losses at Ka-band is much greater than the uncertainty about all other losses on the link combined. Therefore, the traditional link design approach used for X-band links has to be modified. In this paper, we propose a link design approach where the atmospheric noise temperature statistics along with the ground antenna characteristics are used to optimize the average data return on the link. We introduce the mathematical foundations of this approach and present optimal link design strategies for using Ka-band both at 26.5- and at 32-GHz bands for future NASA missions.