The European Space Agency, whose baby LISA Pathfinder is, therefore describes the cube-containing chambers as “the quietest places in the universe”. The craft’s body is designed to protect its payload from pressure exerted by sunlight and the solar wind, and is built from non-magnetic materials. The temperature of the interior is carefully controlled. The experiment also has to deal with the effects of cosmic rays—energetic particles that can zip right through the craft’s skin—for, unchecked, these would cause a slow build-up of electric charge on the masses, which would cause them to move. Such a build-up can, however, be counteracted by using an ultraviolet light to strip electrons, and therefore electric charge, from the cubes.