Li-Ion Rover Batteries and Descent Stage Lithium Thermal Batteries on the Mars Science Laboratory

Abstract

Continuing its pursuit to explore and understand the red planet, and encouraged by the incomparable successes from its Mars Exploration Rovers (MER), Spirit and Opportunity, and more recently the Mars Phoenix Lander, NASA is launching a follow-on Mars surface mission, Mars Science Laboratory (MSL) in the fall of 2009. As before, MSL is aimed at accomplishing the four main science goals of the Mars Exploration Program: i) determine whether life ever arose on Mars, ii) characterize the climate of Mars, iii) characterize the geology of Mars, and iv) prepare for human exploration. With almost a 5-10 fold increase in its capabilities and size compared to MER, MSL has more ambitious goals in terms of exploring a much larger range of latitudes and altitudes than was possible on MER, a longer operating lifespan on Mars' surface of a full Martian year (687 Earth days) or more, while also providing significantly greater mobility and operational flexibility, and enhanced science payload capability. To achieve these goals, MSL is equipped with a radioisotope power system that generates electricity from the heat of plutonium's radioactive decay. To augment this nuclear power source, there will be lithium-ion batteries located on the rover, which have identical chemistry as the Li-ion batteries currently being used on MER and controlled by similar Battery Control Boards (BCB). Further, to assist the Entry, Descent, and Landing (EDL) operations of MSL, which includes a slow sky-crane like terminal descent and landing, as opposed to the solidrocket assisted airbag landing on MER, Li-FeS2 thermal batteries will be utilized on the Descent Stage. In this paper, we will describe the details of the mission requirements, battery trade-offs and designs, and preliminary performance characteristics of these battery systems on MSL.