One way scientists can learn about the history and workings of moons or planets is by studying their magnetic properties with a magnetometer. Goddard scientists hope to test a theory that a stream of charged particles from the Sun, known as the solar wind, smash into the Moon and initiate a chemical process that makes water, or at least hydroxyl, an ingredient of water. Some scientists have suggested that a barrier to this process could be strong magnetic fields. The magnetometer team is building a 3.5-pound (1.6 kilogram) magnetometer. The instrument will deploy by unfurling its 6-foot (2-meter) arm, which will have a sensor at the end. Because the spacecraft itself is magnetic, the instrument needs to be as far away from it as possible to get accurate readings of the surrounding environment.