Lithium ion batteries for Mars exploration missions

The upcoming NASA missions aimed at exploring our Planetary system require batteries that can operate at extreme operating temperatures, with high specific energy and energy densities. Conventional aerospace rechargeable battery systems are inadequate to meet the demands. Lithium ion rechargeable batteries are thus being chosen for these missions. The Mars 2001 (Mars Surveyor Program MSP 01) Lander and the 2003 Mars Sample Return/Athena Rover are among the first of NASA's missions to utilize the lithium ion technology. One common feature of these two missions is the need for the battery to operate well at sub-zero temperatures (down to -30/spl deg/C), at moderate rates of charge and discharge. Elsewhere are therefore focussing on improving the low temperature performance of Li ion cells. Preliminary evaluations of the prototype cells reveal the adequacy of their performance to the needs of these missions.