SECOR Credit - NASA

Geodetic SECOR (Sequential Collation of Range) was an all-weather geodetic survey system which was in operational use for over 3 years, establishing a global survey network. It used the successive positions of artificial satellites in space to determine locations on the earth's surface with exactness over long distances.

The spacecraft notably was used to precisely determine previously uncertain positions of islands in the Pacific. The system consisted of a satellite and 4 ground stations. 3 at geographical points where the co-ordinates had been surveyed accurately and the fourth at an unknown location. Radio waves were flashed from the ground stations to the satellite and returned. The position of the satellite at any time was fixed by the measured ranges from the 3 known stations. Using these precisely established satellite positions as a base, ranges from the satellite to the unknown station were used to compute the position of the unknown station. Geodetic SECOR allows continents and islands to be brought within the same geodetic global grid. Each ground station was entirely portable and contained 3 units: a radio frequency shelter, a data handling shelter and a storage shelter. Lighter weight, solid-state equipment was developed to replace the initial units. The satellite had a mass of 18 kg and contained a transponder, a telemetry system to monitor temperature and operating voltages, and a power unit comprised of solar panels and batteries. Prime Contractor was Cubic Corporation. Experiments with SECOR, together with the Navy's Timation, provided the technical basis for the GPS Navstar system.

Typical orbit: 1978 km circular orbit, 84.9 deg inclination.

• 1962 January 24 - Secor - Launch Site: Cape Canaveral. Launch Complex: LC17B. Launch Vehicle: Delta. FAILURE: Failure.
  

• 1964 January 11 - SECOR 1 - Launch Site: Vandenberg. Launch Complex: SLC1E. Launch Vehicle: Delta. Mass: 18 kg (39 lb). Perigee: 904 km (561 mi). Apogee: 922 km (572 mi). Inclination: 69.90 deg. Period: 103.30 min.
  Located Pacific islands. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1965 March 9 - SECOR 3 - Launch Site: Vandenberg. Launch Complex: SLC2W. Launch Vehicle: Delta. Mass: 18 kg (39 lb). Perigee: 898 km (557 mi). Apogee: 925 km (574 mi). Inclination: 70.10 deg. Period: 103.20 min.
  Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1965 March 11 - SECOR 2 - Launch Site: Vandenberg. Launch Complex: SLC2E. Launch Vehicle: Delta. Mass: 18 kg (39 lb). Perigee: 296 km (183 mi). Apogee: 1,014 km (630 mi). Inclination: 90.00 deg. Period: 97.90 min.
  Failed. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1965 April 3 - SECOR 4 - Launch Site: Vandenberg. Launch Complex: SLC4E. Launch Vehicle: Atlas. Mass: 40 kg (88 lb). Perigee: 1,267 km (787 mi). Apogee: 1,316 km (817 mi). Inclination: 90.20 deg. Period: 111.40 min.
  Failed. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1965 August 10 - SECOR 5 (EGRS 5) - Launch Site: Wallops Island. Launch Complex: LA3A. Launch Vehicle: Scout. Mass: 24 kg (52 lb). Perigee: 1,134 km (704 mi). Apogee: 2,419 km (1,503 mi). Inclination: 69.20 deg. Period: 122.20 min.
  Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

• 1965 August 10 - Secor 5 - Launch Site: Wallops Island. Launch Complex: LA3A. Launch Vehicle: Scout. Perigee: 1,136 km (705 mi). Apogee: 2,424 km (1,506 mi). Inclination: 69.20 deg. Period: 122.22 min.
  

• 1966 June 9 - SECOR 6 - Launch Site: Vandenberg. Launch Complex: SLC3E. Launch Vehicle: Atlas. Mass: 17 kg (37 lb). Perigee: 168 km (104 mi). Apogee: 3,646 km (2,265 mi). Inclination: 90.00 deg. Period: 125.00 min.
  Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1966 August 19 - SECOR 7 - Launch Site: Vandenberg. Launch Complex: SLC3E. Launch Vehicle: Atlas. Mass: 17 kg (37 lb). Perigee: 3,671 km (2,281 mi). Apogee: 3,700 km (2,200 mi). Inclination: 89.70 deg. Period: 167.50 min.
  Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1966 October 5 - SECOR 8 - Launch Site: Vandenberg. Launch Complex: SLC3E. Launch Vehicle: Atlas. Mass: 17 kg (37 lb). Perigee: 3,674 km (2,282 mi). Apogee: 3,707 km (2,303 mi). Inclination: 90.00 deg. Period: 167.60 min.
  Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1967 June 29 - SECOR 9 - Launch Site: Vandenberg. Launch Complex: SLC10W. Launch Vehicle: Delta. Mass: 20 kg (44 lb). Perigee: 3,803 km (2,363 mi). Apogee: 3,940 km (2,440 mi). Inclination: 90.20 deg. Period: 172.10 min.
  Location survey. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1968 May 18 - EGRS 10 - Launch Site: Vandenberg. Launch Complex: SLC2E. Launch Vehicle: Delta. FAILURE: Failure.
  

• 1969 April 14 - SECOR 13 - Launch Site: Vandenberg. Launch Complex: SLC2E. Launch Vehicle: Delta. Mass: 20 kg (44 lb). Perigee: 1,070 km (660 mi). Apogee: 1,129 km (701 mi). Inclination: 100.30 deg. Period: 107.30 min.
  Spacecraft engaged in practical applications and uses of space technology such as weather or communication (US Cat C).