A US nanosatellite mission to measure changes in density of the auroral zone of the upper atmosphere caused by solar stimuli such as flares and coronal mass ejections. The mission involved deploying three aluminium spheres of 10 cm diameter into an elliptical polar orbit and tracking them as they make repeated perigee passes in the upper atmosphere. The satellite was launched on 29 September 2013, from California, into orbit at an altitude of about 340 km perigee, about 1510 km apogee.