Music provided by Killer Tracks: "Innovations" by Pascal Lengagne
Mars has two moons, Phobos and Deimos. Both are small, airless bodies with irregular shapes. Because they lack protective atmospheres and magnetospheres, Phobos and Deimos are directly exposed to the solar wind for part of their orbits. The solar wind is a stream of electrically charged particles constantly blowing off the surface of the sun at about a million miles per hour; as it collides with the moons, it is thought to create complex electrical environments.
Now, a simulation by William Farrell of NASA's Goddard Space Flight Center has revealed the details of Phobos's interaction with the solar wind. The simulation predicts that static electric charging occurs on the night side of Phobos and within its shadowed craters. Phobos is frequently cited as a target for future exploration, but according to the study, any robots or humans roving around the night side could build up static electric charge that might affect sensitive equipment. Mission planners will have to face this challenge as they set their sights on the moons of Mars.