Variable Thermal Conductance Link for Lunar Landers and Rovers

Abstract

The Anchor Node Mission for the International Lunar Network (ILN) has a Warm Electronics Box (WEB) and a battery, both of which must be maintained in a fairly narrow temperature range using a variable thermal conductance link. During the Lunar day, heat must be transferred from the WEB to a radiator as efficiently as possible. During the night, heat transfer from the WEB must be minimized to keep the electronics and batteries warm with minimal power, even with a very low (100 K) heat sink. Three different variable thermal links were identified that could perform this function: 1. A mini-loop heat pipe (LHP), 2. A mini-LHP with a bypass valve, or 3. A Variable Conductance Heat Pipe (VCHP) with a hybrid wick. The paper discusses the advantages and disadvantages of each link. The mini-LHP has the highest Technology Readiness Level, but requires electrical power to shut-down during the 14-day Lunar night, with a significant penalty in battery mass. The mini-LHP with bypass valve and the hybrid loop VCHP require more development, but will require no electrical power for shut-down.