The purpose of this white paper is to provide an overview to the NRC Decadal Survey Inner Planets Sub-Panel on key technologies required for future Venus exploration missions. It covers both heritage technologies and identifies new technologies to enable future missions in all three mission classes. The technologies will focus on mission enabling and enhancing capabilities for in situ missions,

This viewgraph presentation reviews the timeline for the robotic in situ investigation of Titan and Venus, and the use of radioisotope power systems in this exploration. The atmospheric and surface conditions of both sites are reviewed. The presentation also examines the conceptual design of the Venus Mobile Explorer and the Titan orbiter and in situ explorer. After this the presentation reviews the radioisotope power systems for each of the vehicles, with some explanation of the different requirements based on the vastly different environments that they would be investigating

NASA’s 2006 Solar System Exploration (SSE) Strategic Roadmap identified a set of small, medium and large missions, to address exploration targets, set out by the National Research Council (NRC) in the SSE Decadal Survey. Large size Flagship class missions are proposed to target Europa, Titan / Enceladus, Venus, and the Neptune system. Under the current candidate architectures, all of these Flagship class missions would require Radioisotope Power Systems (RPSs), as enabling technologies. Medium size New Frontiers (NF) class missions could also consider RPSs, although the ones targeting the 3rd NF opportunity would not likely utilize them. To constrain costs, small size Discovery class missions are not allowed to use RPSs. The proposed SSE Roadmap missions represent the highest priority subset of a broader collection of mission concepts, called NASA’s SSE Design Reference Mission (DRM) set. In line with the SSE DRM set, the RPS DRM set includes a collection of potential future missions, which could be enabled or enhanced by the use of RPS technologies. Currently, NASA has proposed the development of the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG), with static power conversion; and the Stirling Radioisotope Generator (SRG), with dynamic conversion. Advanced RPSs under consideration for possible development target increased specific power levels, consequently increasing electric power generation for the same amount of fuel, or reducing fuel requirements for the same power output, compared to the proposed MMRTG or SRG. It is expected that the RPSs will need modifications to operate in the extreme environments of Titan or Venus. An RPS on the proposed Titan Explorer would use smaller fins to minimize heat rejection in the extreme cold environment; while the Venus Mobile Explorer long-lived in situ mission would require the development of a new RPS, in order to tolerate the extreme hot environment, and to provide active cooling to the payload and other electric components. This paper discusses NASA’s SSE RPS DRM set in line with the SSE DRM set, and gives a qualitative assessment of the impact of various RPS options on the potential mission architectures. The assessment could aid NASA with RPS technology development planning, and with the understanding of fuel needs over the next three decades.

Abstract. A joint NASA GRC / JPL design study was performed for the NASA Radioisotope Power Systems Office to explore the use of radioisotope electric propulsion for flagship class missions. The Kuiper Belt Object Orbiter is a flagship class mission concept projected for launch in the 2030 timeframe. Due to the large size of a flagship class science mission larger radioisotope power system ‘building blocks’ were conceptualized to provide the roughly 4 kW of power needed by the NEXT ion propulsion system and the spacecraft. Using REP the spacecraft is able to rendezvous with and orbit a Kuiper Belt object in 16 years using either eleven (no spare) 420 W advanced RTGs or nine (with a spare) 550 W advanced Stirling Radioisotope systems. The design study evaluated integrating either system and estimated impacts on cost as well as required General Purpose Heat Source requirements. Keywords : ASRG, SRG-550, ARTG, radioisotope power, REP I NTRODUCTION NASA has successfully developed and la...

The Vision for Space Exploration identified the exploration of Mars as one of the key pathways. In response, NASAs Mars Program Office is developing a detailed mission lineup for the next decade that would lead to future explorations. Mission architectures for the next decade include both orbiters and landers. Existing power technologies, which could include solar panels, batteries, radioisotope power systems, and in the future fission power, could support these missions. Second and third decade explorations could target human precursor and human in–situ missions, building on increasingly complex architectures. Some of these could use potential feed forward from earlier Constellation missions to the Moon, discussed in the ESAS study. From a potential Mars Sample Return mission to human missions the complexity of the architectures increases, and with it the delivered mass and power requirements also amplify. The delivered mass at Mars mostly depends on the launch vehicle, while the l...