The NetLander Network mission concept was designed with up to 10 small landers to perform environmental monitoring on the surface of Mars over a long duty cycle. Each lander would utilize a small Radioisotope Power System (RPS) to generate about 20 to 25 We of electric power. Each small-RPS would use a single General Purpose Heat Source (GPHS) module to generate about 250 Wt of thermal power (BOL), which must be dissipated throughout all phases of the mission. This paper describes a custom concept for a small-RPS, specifically suited for the NetLander, and discusses an analysis of the thermal environment for five phases of the mission. On Earth and on Mars the small-RPS would operate in planetary atmospheres and the waste heat would be removed through a passive radiator. During the cruise phase, including the launch, a fluid loop would provide active cooling to the radiator of the small-RPS and would reject the excess heat through an external radiator. For the entry, descent and landing (EDL) phase the lander would accumulate the excess heat, while building up thermal inertia inside. This analysis provides an initial step towards developing an end-to-end systems approach to better understand the operation of a small-RPS, and to account for the relevant operating phases and environments encountered during a mission.

Advanced RPS concepts can be conceived, designed and assessed using high-end computational analysis tools. These predictions may provide an initial insight into the potential performance of these models, but verification and validation are necessary and required steps to gain confidence in the numerical analysis results. This paper discusses the findings from a numerical validation exercise for a small advanced RPS concept, based on a thermal analysis methodology developed at JPL and on a validation database obtained from experiments performed at Oregon State University. Both the numerical and experimental configurations utilized a single GPHS module enabled design, resembling a Mod-RTG concept. The analysis focused on operating and environmental conditions during the storage phase only. This validation exercise helped to refine key thermal analysis and modeling parameters, such as heat transfer coefficients, and conductivity and radiation heat transfer values. Improved understanding of the Mod-RTG concept through validation of the thermal model allows for future improvements to this power system concept.