The first large US signals intelligence satellite. Placed into near-geosynchronous orbits. They were misidentified by some analysts as missile warning satellites.

Typical orbit: 32198 km x 39395 km at .2 to 10.3 degrees inclin. Mass: 700 kg (1,540 lb). Associated Launch Vehicle: Atlas / Agena D SLV-3A.

• 1968 August 6 - Canyon 1 - Launch Site: Cape Canaveral. Launch Vehicle: Atlas / Agena D SLV-3A. Mass: 700 kg (1,540 lb). Perigee: 31,680 km (19,680 mi). Apogee: 39,860 km (24,760 mi). Inclination: 9.90 deg. Period: 1,436.00 min.

  First launch in a communications intelligence program operated by the USAF within the National Reconnaissance Office, on behalf of the National Security Agency. The first generation series, CANYON, was based on the Agena vehicle. The Agena D remained attached to the spacecraft. Positioned in geosynchronous orbit over the Indian Ocean. Last known longitude (30 December 1968) 98.50 deg W drifting at 0.166 deg E per day.

• 1969 April 13 - Canyon 2 - Launch Site: Cape Canaveral. Launch Vehicle: Atlas / Agena D SLV-3A. Mass: 700 kg (1,540 lb). Perigee: 32,670 km (20,300 mi). Apogee: 39,270 km (24,400 mi). Inclination: 9.90 deg. Period: 1,445.00 min.

  Positioned in geosynchronous orbit over the Indian Ocean. Last known longitude (31 December 1969) 99.24 deg W drifting at 2.246 deg W per day.

• 1970 September 1 - Canyon 3 - Launch Site: Cape Canaveral. Launch Vehicle: Atlas / Agena D SLV-3A. Mass: 700 kg (1,540 lb). Perigee: 31,947 km (19,850 mi). Apogee: 39,855 km (24,764 mi). Inclination: 10.30 deg. Period: 1,441.90 min.

  Positioned in geosynchronous orbit over the Indian Ocean. Last known longitude (31 December 1970) 99.01 deg W drifting at 1.490 deg W per day.

• 1971 December 4 - AFP-827 / Canyon 4 - Launch Site: Cape Canaveral. Launch Vehicle: Atlas / Agena D SLV-3A. FAILURE: First stage failure. Mass: 700 kg (1,540 lb).

• 1972 December 20 - Canyon 5 - Launch Site: Cape Canaveral. Launch Vehicle: Atlas / Agena D SLV-3A. Mass: 700 kg (1,540 lb). Perigee: 31,012 km (19,269 mi). Apogee: 40,728 km (25,307 mi). Inclination: 9.70 deg. Period: 1,440.40 min.

  First launch of improved ELINT satellite. In comparison to earlier Canyon ELINT satellites, Improved Canyon had a similar but heavier payload which separated from the Agena D final stage.

• 1975 June 18 - Canyon 6 - Launch Site: Cape Canaveral. Launch Vehicle: Atlas / Agena D SLV-3A. Mass: 700 kg (1,540 lb). Perigee: 30,200 km (18,700 mi). Apogee: 40,800 km (25,300 mi). Inclination: 9.00 deg. Period: 1,422.00 min.

• 1977 May 23 - Canyon 7 - Launch Site: Cape Canaveral. Launch Vehicle: Atlas / Agena D SLV-3A. Mass: 700 kg (1,540 lb). Perigee: 35,679 km (22,169 mi). Apogee: 35,855 km (22,279 mi). Inclination: 0.20 deg. Period: 1,435.10 min.

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

• Lockheed Martin Coporation, Atlas Family Fact Sheets, September 1998.. Accessed at: http://www.lmco.com/ILS/txtmain/ils_lsysinfo.htm.

• McDowell, Jonathon, Quest, "US Reconnaissance Satellite Programs Part 2", 1995, Volume 4, Issue 4, page 49.

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

• 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/.

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