Scheduling Within a Demand Access Paradigm for NASA's Deep Space Network

NASA’s Deep Space Network (DSN) is the primary resource for communications and navigation for inter- planetary space missions, for both NASA and partner agencies. As part of an investigation into improved effi- ciency and responsiveness, we have been exploring and prototyping the infusion of a ”demand access” model into the DSN scheduling process. Today, DSN is fully pre-scheduled in advance, and many users rely on a stable schedule to plan their own spacecraft activities, weeks in advance of execution. However, a new class of missions is emerging that may not be scheduled as far in advance, and may be event-driven in coming across sci- ence targets at unpredictable times. These users could take advantage of an on-demand mechanism to down- load data. In this paper, we describe a prototype of the demand access process which consists of reserving blocks of shared antenna time (demand access tracks) and utilizing special ”beacon” tracks to request access to those blocks. Furthermore, we dive into a proposed scheduling solution for the beacon tracks using an ag- gregated value function in order to minimize data la- tency and track starvation.