A low-cost space mission by the US Naval Research Laboratory that monitors the neutral density of the thermosphere at a height of about 400 km, in order to improve the determination of resident space objects. The experiment comprises two minisatellites that were launched into near-circular orbit from the Space Shuttle on 10 December 2006 and retired in 2008. A follow-up mission, ANDE-2, comprising two microsatellites was launched on 30 July 2009 and ended in 2010.