Mars Pathfinder Active Heat Rejection System: Successful Flight Demonstration of a Mechanically Pumped Cooling Loop

Abstract

One of the new technologies successfully demonstrated on the recent Mars Pathfinder mission was the active Heat Rejection System (HRS). This system consisted of a mechanicaily pumped cooling loop, which actively controlled the temperatures of the various parts of the spacecraft. A single phase Refrigerant 11 liquid was mechanically circulated through the lander and cruise electronics box heat exchangers. This liquid transferred the excess heat to an external radiator on the cruise stage. This is the first time in unmanned spacecraft history that an active heat rejection system of this type has been used on a long duration spacecraft mission. Pathfinder was launched in December 1996 and landed on the Martian surface on July 4, 1997. The system functioned flawlessly during the entire seven months of flight from Earth to Mars. A life test set up of the cooling loop was used to verify the life of the system. The life test system was run for over 14, 000 hours before complete examination of the components used in the life test was made. Some of the components used in the system were tested in the life test set up. The results from the life test loop indicate no major issues that would hinder the pumped loop operation for many more years.

Design of Accumulators and Liquid/Gas Charging of Single Phase Mechanically Pumped Fluid Loop Heat Rejection Systems

“…Hence if the maximum liquid stroke is ΔV bellows_stroke , then this should also be the difference of the maximum and minimum gas volumes, as shown in Eq. (4).…”

“…HE MSL mission, currently en route to Mars, follows the general design paradigm of the previous JPL rover missions to Mars (Mars Pathfinder, MPF 1,2,3,4,5 and Mars Exploration Rovers, MER 6,7 ). The external configuration of the MSL spacecraft looks similar to that of MPF and MER.…”

Margin Determination in the Design and Development of a Thermal Control System

“…The original design philosophy for the MER spacecraft was a replica ("build-to-print") of the similar 1996-1997 Mars Pathfinder design which performed successfully. 7 Unfortunately, due to the fundamentally different configuration of the rover having all the "smarts", as opposed to all the "smarts" on the lander electronics module for Pathfinder, the MER design had significant changes.…”

Active Heat Rejection System on Mars Exploration Rover — Design Changes from Mars Pathfinder

“…designed and used on MPF and which worked so well, was planned to be used for MER. The design of the HRS has been documented elsewhere (Bhandari Birur et al, 1998;and Lam, Birur & Bhandari 2002) and will be discussed minimally in the next section to provide context for the remainder of the paper.…”