On the Size of the Mission Suite Enabled by NASA's Deep Space Network

Abstract

The Deep Space Network (DSN) is the primary means of commanding, tracking, and receiving data from all of NASA's deep space missions, as well as a number of deep space missions operated by other international space agencies. The current number of missions enabled by the DSN is approximately 40 missions, but there has been concern about the level of "over-subscription" of the DSN, namely that the number of missions currently using the DSN is larger than can be enabled reasonably. This manuscript assesses the maximum number of missions that could be enabled, based on recent performance and with the constraint that the total number of hours used per week does not exceed the available number of DSN antenna-hours. Three different models are considered, and the maximal number of missions that could be enabled ranges between approximately 40 missions and 70 missions, assuming that there continues to be approximately six Mars missions and that those Mars missions continue to make use of the DSN's multiple spacecraft per antenna (MSPA) capability. Crucially, the conclusion that an approximately 50% growth in the DSN mission suite rests on the assumption that the DSN antennas are "interchangeable," but they are not, with some spacecraft able to use only certain antennas. Efforts to make the DSN antennas more "interchangeable," primarily in their transmitter and receiver suites, would be an effective means of ensuring expanded capability. Additional findings from this work are that, while additional use of the MSPA capability might appear to be a promising means for increasing the mission suite, there appear to be no locations in the Solar System, other than Mars, for which it would be effective.