Using solar power on the Martian surface is challenging because the Martian atmosphere has a significant amount of dust suspended in it. In addition to blocking sunlight from reaching Mars's surface, dust particles gradually settle out of the air and onto objects. As Pathfinder was NASA's first Mars surface mission to be solar-powered, the effect of Martian dust settling on solar cells was not well understood before the mission. It was predicted at the time that dust particles in the Martian atmosphere would settle on the solar cells powering Pathfinder, blocking sunlight from striking them and slowly causing Pathfinder to lose power. Since knowing how the settling of dust out of Mars's atmosphere would affect solar cell performance would be critical to subsequent solar-powered missions on Mars, the MAE was included aboard the Sojourner rover to measure the degradation in performance of a solar cell as dust settled.
