Typical orbit: 585 km circular orbit, 63.5 deg inclination. Mass: 180 kg (390 lb). Associated Launch Vehicle: Pegasus, Pegasus XL.

• 1994 June 27 - STEP 1 - Program: STEP. Launch Site: Vandenberg. Launch Vehicle: Pegasus XL. FAILURE: Destroyed on launch. Apogee: 38 km (23 mi).

  Destroyed on launch

• 1994 May 19 - STEP 2 (SIDEX) - Program: STEP. Launch Site: Edwards. Launch Vehicle: Pegasus. Mass: 180 kg (390 lb). Perigee: 597 km (370 mi). Apogee: 813 km (505 mi). Inclination: 82.00 deg. Period: 98.90 min.

  Did not achieve planned orbit, though still useful. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1997 October 22 - STEP-4 - Program: STEP. Launch Site: Wallops Island. Launch Vehicle: Pegasus XL. Perigee: 432 km (268 mi). Apogee: 500 km (310 mi). Inclination: 45.00 deg. Period: 93.80 min.

• McDowell, Jonathan, Jonathan's Space Report (Internet Newsletter), Harvard University, Weekly, 1989 to Present. Essential internet newsletter recording worldwide weekly space events. Accessed at: http://www.planet4589.org/jsr.html.

• Krebs, Gunter, Gunter's Space Page, University of Frankfurt, 1996. Accessed at: http://www.skyrocket.de/space.

• McDowell, Jonathan, Jonathan's Space Home Page, Harvard University, 1997-present. Jonathan McDowell's complete on-line listing of all objects orbited and over 20,000 rocket launches Accessed at: http://www.planet4589.org/jsr.html.

• USAF Satellite Database, USAF Institute of Technology, 1995. Accessed at: ftp://archive.afit.af.mil/pub/space/.

• JPL Mission and Spacecraft Library, Jet Propulsion Laboratory, 1997. Accessed at: http://msl.jpl.nasa.gov/home.html.