Geosynchronous orbit signals intelligence satellite series that replaced Canyon. Also called Program 366 and Vortex.

Typical orbit: 10209 x 23186 km, 22.4 deg inclinaton. Mass: 932 kg (2,054 lb). Associated Launch Vehicle: Titan 34D, Titan 3C.

• 1978 June 10 - Chalet 1 - Launch Site: Cape Canaveral. Launch Vehicle: Titan 3C. Mass: 820 kg (1,800 lb). Perigee: 29,929 km (18,596 mi). Apogee: 42,039 km (26,121 mi). Inclination: 12.00 deg. Period: 1,446.30 min.

  First launch of the heavier, mored advanced CHALET ELINT satellites. (the project was renamed VORTEX when the code name CHALET appeared in the New York Times).

• 1979 October 1 - Chalet 2 - Launch Site: Cape Canaveral. Launch Vehicle: Titan 3C. Mass: 820 kg (1,800 lb). Perigee: 30,443 km (18,916 mi). Apogee: 41,497 km (25,784 mi). Inclination: 7.50 deg. Period: 1,445.50 min.

  Chalet ELINT satellite.

• 1981 October 31 - Chalet 3 - Launch Site: Cape Canaveral. Launch Vehicle: Titan 3C. Mass: 820 kg (1,800 lb). Perigee: 134 km (83 mi). Apogee: 382 km (237 mi). Inclination: 29.30 deg. Period: 90.40 min.

  Chalet ELINT satellite.

• 1984 January 31 - Chalet 4 - Launch Site: Cape Canaveral. Launch Vehicle: Titan 34D. Mass: 1,043 kg (2,299 lb). Perigee: 146 km (90 mi). Apogee: 1,023 km (635 mi). Inclination: 29.40 deg. Period: 96.40 min.

  Chalet ELINT satellite.

• 1988 September 2 - USA 31 - Launch Site: Cape Canaveral. Launch Vehicle: Titan 34D. FAILURE: Broken Transtage pressurization feed lines prevented the geosynchronous orbit apogee burn from taking place. Mass: 1,045 kg (2,303 lb). Perigee: 151 km (93 mi). Apogee: 14,103 km (8,763 mi). Inclination: 29.30 deg. Period: 99.80 min.

  Chalet ELINT satellite; upper stage failure left in lower than planned orbit.

• 1989 May 10 - USA 37 - Launch Site: Cape Canaveral. Launch Vehicle: Titan 34D. Mass: 1,045 kg (2,303 lb). Perigee: 455 km (282 mi). Apogee: 40,073 km (24,900 mi). Inclination: 27.50 deg. Period: 720.00 min.

  Chalet ELINT satellite.

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

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

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

• McDowell, Jonathan, Launch Log, October 1998. Jonathan McDowell's complete on-line listing of all objects orbited since Sputnik. Accessed at: http://hea-www.harvard.edu/~jcm/space/log/launch.html.