Mars is becoming a proving ground for the lifetimes of lithium-ion batteries. The Phoenix Mars Lander is carrying Lithion modules from Yardney Technical Products Inc. When it lands on May 25, after a 423 million mile journey, the batteries will power the vehicle at night when solar panels can’t. Yardney’s intergalactic durability was already proven in the Mars Exploration Rovers launched in 2003. One of the spacecraft’s jobs will be to study the history of water, reusing instruments from two earlier Mars landers, one that failed to work and one that wasn’t launched.