Polar, as its name implies, will be in a polar orbit around the earth, and explores the magnetosphere in the polar regions. It was launched in February 1996, and its orbit carries it from 1.8 Re to 10 Re. SSL is in charge of an electric field instrument on board. The EFI includes three sets of double spherical probes, two pairs of which extend to separations of 100 m or more on wire booms in the spacecraft spin plane, and the other pair are spaced along the spacecraft spin axis on rigid booms that keep them 14 m apart. Click on satellite image to enlarge.