DMSP (Defense Meteorological Satellite Program)

What is DMSP?

The Defense Meteorological Satellite Program (DMSP) is a US Department of Defense spacecraft constellation that provides Earth weather and environmental data. DMSP instruments provide information in the visual and infrared spectra about the motion and characteristics of Earth’s clouds, land, ice and water. The DMSP satellites have included plasma sensors provided by UT Dallas since the eighth satellite (DMSP-F8) was launched in 1987. The UT Dallas plasma program has spanned more than three decades with operational instruments on 12 DMSP spacecrafts, three of which are still operational in 2022.

Launch and Operation

DMSP satellites have been carried to orbit on a range of launch vehicles including the ULA Atlas V and Delta IV. Placed in an ~850 km, polar, sun-synchronous orbit at an inclination of 99 degrees, each satellite orbit maintains a fixed orientation with respect to the sun, allowing it to repeatedly scan a fixed set of local times in orbit. By combining data from a constellation of several satellites (generally in two to four different local time orbits) a continuous global view is obtained.

The SSIES Instrument

The plasma sensors provided for the DMSP missions have changed over the years, with the latest series designated as SSIES-3, being the third version of the Special Sensor lon Electron and Scintillation instrument. The SSIES-3 is a full array of plasma sensors, including an lon Drift Meter (IDM), Retarding Potential Analyzer (RPA), Electron Sensor (ES), Plasma Plate (PP) and Scintillation Meter (SM). The IDM and RPA together provided the local ion drift vector, temperature and composition (H+, He+, and O+). The SM provides the frequency spectrum of ion density variations and a high sample rate measure of the ion density. The ES is a gridded spherical probe that measures characteristics of the local electron population.

Mission Data and Impact

The upper atmosphere in the polar regions is where the Earth’s magnetic field couples directly with the magnetic field and plasma from the solar wind. This coupling transmits energy from the solar wind into the Earth’s magnetosphere, ionosphere, and thermosphere driving various geomagnetic phenomenon including the Earth’s aurora (northern and southern lights). When a large amount of energy is transferred from the solar wind this results in geomagnetic storms. A large-scale horizontal convection pattern of the ion flow is created by the interaction with the solar wind, most commonly in the form of a two-cell flow where ions move from the dayside towards the nightside at the highest latitudes while at lower latitudes on both sides there is a return ion flow to the dayside. During geomagnetic storms, this flow pattern covers a larger area and the flow speeds increase. An example of a quiet-time horizontal flow pattern from DMSP-F16, F17, and F18 data is shown in the upper figure from March 16, 2013 while the pattern from 24 hours later during the March 17, 2013 geomagnetic superstorm is shown in the lower figure.