Magnetic field data.

Typical orbit: 221 km x 181100 km at 33 degrees inclination. Mass: 34 kg (74 lb). Associated Launch Vehicle: Delta, Juno II.

• 1961 February 25 - Explorer - Program: Explorer. Launch Site: Cape Canaveral. Launch Vehicle: Jupiter. FAILURE: Third Stage failed to ignite. Mass: 34 kg (74 lb).

• 1961 March 25 - Explorer 10 - Program: Explorer. Launch Site: Cape Canaveral. Launch Vehicle: Delta. Mass: 35 kg (77 lb). Perigee: 221 km (137 mi). Apogee: 181,100 km (112,500 mi). Inclination: 33.00 deg. Period: 5,013.90 min.

  Magnetic field data. Decay date suspect Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

• 1961 May 24 - Explorer S-45A - Program: Explorer. Launch Site: Cape Canaveral. Launch Vehicle: Jupiter. FAILURE: Second Stage failed to ignite. Mass: 33 kg (72 lb).

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

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

• Bramscher, Robert G, Spaceflight, "A Survey of Launch Vehicle Failures", 1980, Volume 22, page 351.

• 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.