- 13 March 1994 STEP-0 Spacecraft: TAOS. Mass: 502 kg. Launch Site: Vandenberg . Launch Vehicle: Taurus. More details
Space Test Experiment Program; 10 satellite subsystem experiments. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).
- 19 May 1994 STEP 2 (SIDEX) Spacecraft: Eagle. Mass: 180 kg. Launch Site: Edwards . Launch Vehicle: Pegasus. More details
Did not achieve planned orbit, though still useful. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).
- 27 June 1994 STEP 1 Spacecraft: Eagle. Launch Site: Vandenberg . Launch Vehicle: Pegasus XL. More details
Destroyed on launch
- 22 June 1995 STEP 3 Spacecraft: STEP. Mass: 267 kg. Launch Site: Vandenberg . Launch Vehicle: Pegasus XL. More details
Space Test Experiment Platform.
- 22 October 1997 STEP-4 Spacecraft: Eagle. Launch Site: Wallops Island . Launch Vehicle: Pegasus XL. More details