Thermal Analysis of a Small-RPS Concept for the Mars NetLander Network Mission

Abstract

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.

RPS strategies to enable NASA's next decade robotic Mars missions

“…High power modes would include the continuous operation of the seismometer and periodic telecom. The small-RPS configuration would be specific to this lander, because the power system would be embedded inside the structure and would have to survive the high g-loads (up to 2000g) during landing on a crushable material enabled aeroshell [13]. If required, the number of lenders could be expanded up to 10 elements.…”

“…However, some of the earlier mission phases could also impact the design. This is particularly relevant for RPS enabled missions, where the heat generated by these power systems must be mitigated during Earth storage, launch, cruise and EDL (entry, descent and landing) phases, in addition to the surface operation phase [13].…”