First use of a Delta dual payload attach fitting. The Earth Orbiter 1 satellite was part of NASA's New Millenium Program. Complementing the New Millenium's Deep Space series, EO-1 was a NASA-Goddard satellite which demonstrated technology for the next generation Landsat. It flew in formation with Landsat-7 for comparison purposes, using a hydrazine thruster to adjust its orbit. The satellite used a MIDEX-derived bus built by Swales Aerospace; dry mass was 566 kg. The main instruments were ALI (Advanced Land Imager) and the Hyperion 220-band imaging spectrometer. At 1835 GMT the Delta second stage completed its first burn and entered a 185 x 713 km x 98.2 deg transfer orbit. At 1920 GMT the orbit was circularised and EO-1 separated at 1925 GMT into a 682 x 729 km x 98.2 deg orbit.

The five simultaneously-launched Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites were the fifth medium-class mission under NASA's Explorer Program. They formed part of a combined ground- and space- based system designed to determine what physical process in near-Earth space initiate the violent eruptions of the aurora that occur during substorms in the Earth's magnetosphere.