APL Space Department Special Sensor Ultraviolet Spectrographic Imager Launched on October 18, 2003 (see launch pics)

Overview	For a 15 year period, the Defense Meteorological Satellite Program (DMSP) satellites will carry SSUSI, which is a combination of spectrographic imaging and photometric systems designed to remotely sense the ionosphere and thermosphere. The long term focus of the SSUSI program will provide data concerning the upper atmospheric response to the sun over a large portion of the solar cycle.
Mission	SSUSI is under development for the DMSP Block 5D-3 satellites. These satellites will be placed into a nearly polar, sun-synchronous orbit at an altitude of about 830 km. SSUSI is a remote-sensing instrument which measures ultraviolet (UV) emissions in five different wavelength bands from the Earth's upper atmosphere. SSUSI will be mounted on a nadir-looking panel of the satellite. The multicolor images from SSUSI cover the visible Earth disk from horizon to horizon and the anti-sunward limb up to an altitude of approximately 520 km. The UV images and the derived environmental data provide Air Force Space Forecast Center (Falcon Air Force Base, Colorado Springs, CO) with near real-time information which can be utilized in a number of applications, such as maintenance of high frequency (HF) communication links and related systems and assessment of the environmental hazard to astronauts during Space Shuttle missions.
Instruments	SSUSI consists of · a Scanning Imaging Spectrograph (SIS) with a cross track line scan mirror · a system of three nadir-looking photometers (NPS) which operate in the visible portion of the electromagnetic spectrum. The SIS produces simultaneous monochromatic images at five "colors" in the spectral range 115nm to 180nm. The NPS consists of three photometers with filters designed to monitor the airglow at 427.8nm and 630nm and the terrestrial albedo near 630nm.
Data Analysis	Two Ground Data Analysis Software modules will be used to process the SSUSI sensor data at AFSFC. The Algorithms module will create SSUSI Sensor Data Records (SDRs) and Environmental Data Records (EDRs). The SDRs contain data directly measured by the sensors, such as photometer counts, uncertainties, light intensities and pointing information derived from the SSUSI raw sensor data, the satellite ephemeris data obtained from the Air Force Global Weather Central (AFGWC), and data obtained from the AFSFC relational databases. The EDRs contain environmental parameters which are derived from the sensor data by scientific algorithms specific to day, night and auroral regions. The User Interface module will provide AFSFC personnel with a capability to display selected SSUSI data to support AFSFC operations. All SSUSI ground software was developed under tailored requirements of DOD-STD-2167A, using Object Oriented Design methodology.
Papers  (in PDF)	The environmental parameters produced by SSUSI and the associated algorithms. The SSUSI instruments: SIS and NPS.
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