The Naval Research Laboratory has built give Special Sensor Ultraviolet Limb Imagers (SSULIs) for the Defense Meteorological Satellite Program. These sensors are designed to measure vertical intensity profiles of the Earth's airglow in the extreme and far ultraviolet (800 to 1700 angstroms). The data from these sensors will be used to infer altitude profiles of ion, electron and neutral density. The first SSULI is scheduled to launch in 2000. An identical copy of the SSULI sensor called LORAAS was launched aboard the ARGOS spacecraft on February 23, 1999. Data from LORAAS will be used to verify the performance of the SSULI sensors, ground analysis software and validate the UV remote sensing technique. Together with the LORAAS instrument the SSULI program will collect data on the composition of the upper atmosphere for a complete solar cycle.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.