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SSUSI: Mission Objectives

 
APL is building five state-of-the-art sensors for DMSP. These sensors, the SSUSI, are intended to provide a quantitative description of the state of the upper atmosphere and the aurora on a global basis. In order for the data to be of use to the user community, rapid, efficient, and accurate operational algorithms must be developed to convert the radiance observations into environmental parameters.

The SSUSI design reflects the operational need for the monitoring of global space weather. Memorandum of the Joint Chief of Staff MJCS 154-86 ranked environmental parameters in order of priority. Table 1 summarizes those parameters with priority ranking that SSUSI will measure.

Table 1. MJCS 154-86 Rank of SSUSI Environmental Parameters
Rank Environmental Parameter
5 Electron Density Profile
12 Neutral Number Density Profile
16 Solar Radiation (EUV integrated flux)
18 Auroral Emissions and Airglow
24 Precipitating Electrons and Ions
26 Electric Fields
31 Ionospheric Scintillation

The FUV is ideally suited to determining thermospheric and ionospheric environmental parameters. It possesses optical signatures of all the major thermospheric species: O, N2, and O2 (O2 is seen in absorption on the limb) and the dominant F-region ion, O+ (on the nightside).