Demand Access for NASA’s Deep Space Network: A New Paradigm for Operations

NASA’s Deep Space Network supports the communications to and from spacecraft, rovers, and landers across our solar system and beyond. The weekly tracking requirements for these spacecraft are scheduled by mission representatives at least eight weeks before the start of the track through a combination of automated algorithms and peer-to-peer negotiations. This process has worked well for traditional users with deterministic science collections, such as those doing mapping and imaging. But this process will not scale well to accommodate a new class of users whose data collections are not completely predictable (i.e., event-driven science), which includes both traditional, deterministic users with unexpected discoveries as well as autonomous users exploring and monitoring for certain events, such as solar flares. In this paper, we propose a “demand access” scheduling approach in which the spacecraft, rovers, and landers themselves request track time on the network using a beacon-tone system and are scheduled track time “on-the-fly” using pre-scheduled shared-user block tracks. We show through simulation that this demand-access approach can both decrease the mean duration between the time of data collection to the start of the downlink and the number of tracks required compared to the traditional scheduling method for an example mission concept of autonomous SmallSat explorers at near-Earth asteroids. We also show how this demand-access approach can be used in combination with the traditional scheduling method to support legacy users.