Mars rovers using AFRL batteries Published July 16, 2003 By Sarah Hubbard Air Force Research Laboratory Propulsion Directorate WRIGHT-PATTERSON AIR FORCE BASE, Ohio (AFPN) -- As the Mars exploration rovers "Spirit" and "Opportunity" race toward the Red Planet, part of the Air Force Research Laboratory is soaring with them.The two rovers, expected to touch down and explore opposite sides of Mars in early 2004, are powered by rechargeable lithium-ion batteries researched and developed by experts at the laboratory’s propulsion directorate. Spirit and Opportunity will act as robot geologists while on the surface of Mars.To search for and characterize a wide range of rocks and soils that hold clues to past water activity on Mars, NASA officials needed a more powerful, lightweight battery to withstand extreme temperatures and provide more electricity to the rovers. Directorate officials said the new batteries will allow Spirit and Opportunity to perform on-site scientific investigations during the course of their 90-day missions and trek up to 40 meters per day.Steve Vukson, a chemical engineer, said researchers in the directorate's power division were already working on a new type of battery that exceeded commercial-battery performance and fit NASA's needs. A joint lithium-ion battery program was established by experts in NASA's Glenn Research Center, the Jet Propulsion Laboratory and the propulsion directorate.The new rovers need about 100 watts (equivalent to a standard light bulb) to operate, NASA officials said. Comparatively, the Sojourner rover's solar arrays provided the 1997 Pathfinder mission with a maximum of around 16 watts of power, the amount used by an oven light.The extra power provided by the new batteries will enable the Spirit and Opportunity to conduct more research, NASA experts said.To get the most out of their new technology, the two rechargeable batteries are stored in a warm box, which houses the rover's power system, Vukson said."It contains a heater that helps maintain the temperature of the batteries' environment, allowing for it to operate in the extreme temperatures of space," he said.The solar arrays on top of the box attract sunlight as a source of energy and generate up to 140 watts of power to the batteries. This stored energy will power the rover as it explores the planet's surface, Vukson said.NASA officials said that during the day, the solar arrays power the rover while the batteries store the energy. After nightfall, the rover powers up with stored energy from the battery. The true test of the batteries' capabilities will be when the rovers arrive in January where they will explore, fully powered by the new batteries, Vukson said.