Mission Analysis for Next-Generation RTG Study

The Next-Generation Radioisotope Thermoelectric Generator (RTG) Study was carried out in 2016-2017 to determine the characteristics of options for a new RTG that would best fulfill NASA Planetary Science Division (PSD) mission needs, considering applicability to different targets and mission types. The NASA Radioisotope Power Systems (RPS) Program Mission Analysis Team gathered information on past and recent RPS mission concept studies by various organizations in the United States to support the Next-Generation RTG Study in crystalizing an understanding of mission "pull" that is crucial to define requirements for a potential next generation of RTGs. This paper describes the top-down processes and findings that helped establish a reasonable set of draft requirements for a potential Next-Generation RTG, which are documented in the Next-Generation RTG Study final report. To perform the required mission analyses, and to combine data and present the results in a unique way, an extensive relational database was developed. The database includes detailed data for 63 targets, six generic potential destinations (comet, Trojan, Centaur, etc.), 142 spacecraft concepts (65 launched and 77 studied), and 249 missions associated with these spacecraft concepts. In total, 77 RPS-powered spacecraft and associated mission concept studies were gathered, evaluated and assessed for the Next-Generation RTG Study. A number of spacecraft are associated with a number of mission concept types/subtypes at different destinations; thus, in this report, a mission is defined as a unique vector of spacecraft, mission concept type (e.g., lander) /subtype (e.g., rover), and target. For example, Cassini conducted flybys of Enceladus and 2685 Masursky, and orbited Saturn, which is considered three missions under this definition. Furthermore, there are two categories of spacecraft concepts: launched missions (e.g., Cassini, Mars Science Laboratory [MSL]) and concepts studied for possible future missions.