Caption: 
SwRI’s LMS instrument will be the first extraterrestrial application of magnetotellurics from aboard a lunar lander to Mare Crisium, an ancient, 350-mile-diameter impact basin that subsequently filled with lava. The basin is one of many large dark spots on the Moon’s surface visible to the naked eye. They were dubbed lunar maria, Latin for "seas," by early astronomers who mistook them for actual seas.