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

Abstract

The active Heat Rejection System designed for Mars Pathfinder was modified for the Mars Exploration Rover (Mars '03) mission and will be used to remove excess heat from the Rover electronics during the cruise part of the mission. The Integrated Pump Assembly design from MPF remained essentially intact; changes were primarily made to reduce weight. However, the cooling loop was significantly redesigned to service totally different requirements for the MER rovers. In addition, the vent design was readdressed to alleviate potentially excessive nutation as was induced on the MPF spacecraft in the process of dumping the R11 overboard prior to Entry/Descent/Landing. The current vent design was based on a better understanding of the flow characteristics during the blowdown process. This paper addresses some of the key design changes. This paper also addresses lessons learnt from the performance testing, and potential changes to improve the HRS performance (e.g, temperature oscillations).

JPL Thermal Design Modeling Philosophy and NASA-STD-7009 Standard for Models and Simulations - A Case Study

“…The design and performance of this system has been well documented. 9,10 To address lessons learned on MPF 11 , the thermal design for the cruise stage propellant lines used the following upgraded features from the MPF design: 1) flight software controlled heaters, rather than mechanical bimetallic thermostats; 2) 8 distinct thermal regions, instead of 4; and 3) locating of line heaters at high heat loss areas (i.e., propellant line mounting supports), rather than a uniform heater power density over a control zone. Each control zone had two heaters for single point failure tolerance.…”

Uncertainty Quantification in Conceptual Design via an Advanced Monte Carlo Method

“…This decision in turn impacted the thermal design. 21 Lastly, the third stage of the Boeing Delta II launch vehicle that was used to inject MER on its interplanetary trajectory was spun up to 70-80 rpm for gyroscopic stiffness against disturbances during operation of its solid rocket motor. After the solid rocket motor burned out, the spin rate was reduced to 12 rpm by the launch vehicle's yo-yo de-spin system, and reduced further to 2 rpm by the ACS for the entire cruise to Mars.…”

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

“…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.…”