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DSN Downlink Model 5 One realization of a simulated schedule is not sufficient; track location affects the total downlink possible. Many realizations are generated and statistics of the data volumes are used to produce a better model of potential science data downlink. Downlink model uses past DSN schedules to simulate a realistic schedule randomly distributed across stations. Duration and grouping of tracks are characteric of actual schedules, which are human-generated and negotiated across many space missions. 1) Select contiguous period of interest and number of hours per day of average track time 2) Randomly sample probability distribution above so that track lengths are distributed according to model, stopping when total track time results in required hours/day 3) Randomly distribute tracks throughout period of interest, selecting DSN antenna at random Procedure for Model Schedule Track Length Distribution 4 Figure above shows the distribution of track lengths (blue symbols) for the first half of the PSP mission. By a large margin, the most likely track length is 2.5 hours long. There are generally few tracks less that 2.5 hours long, and few tracks greater than 11 hours long. The black curve is a "by eye" fit to the data shown. Namely, it is a normalized probably density curve selected to qualitatively represent the strongly peeked distribution of track lengths. DSN Schedule 3 On the left is a three-day period of possible downlink rates. Transmission rates are discrete, and vary based on PSP's location in the sky. On the right is the final DSN schedule for the same period. Based on the complex, antenna, and period of time scheduled, downlink volume can vary. Deep Space Network 2 Three DSN complexes around the world provide near-continuous link for missions outside the Moon's orbit. The figure above shows possible PSP transmission rates using PSP's Ka-band high gain antenna (HGA). PSP does not downlink science data during Encounter periods close to the Sun (gray); other periods without possible downlink (white) are due to Earth-Sun-Probe geometry (i.e., conjuctions). Abstract 1 Parker Solar Probe (PSP) uses the Deep Space Network (DSN) for all telecommunications operations. The process by which PSP makes requests, and the DSN allocates time and resources, is based on many evolving factors that are both opaque to science downlink planners and result in considerable uncertainty in the resultant science downlink volume. A statistical model that allows more accurate projection, including uncertainty, of the science data downlink has been developed based on PSP’s early mission; this model allows the stochastic generation of a DSN schedule for science downlink based on simple input parameters typically given to the DSN scheduler (e.g., X hours per day of downlink). The model developed to facilitate the planning process and optimize science data return is presented. Deep Space Network Schedule Modeling for the Parker Solar Probe Mission D.J. Rodgers, N. Pinkine, D.M. Sepan Johns Hopkins University Applied Physics Laboratory DASH/IHDEA 2025
