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Calsphere 1, 2, 3, 4

Calsphere [NRL]

The Calsphere (Calibration Sphere) satellites were passive spherical surveillance calibration target built by the Naval Research Laboratory (NRL).

These satellites were launched on three cluster launches of multiple small satellites:

  • Calsphere 1 was launched on a Thor-DM21 Agena-D in December 1962 with a pair of Poppy 3 SIGINT satellites and some small payloads, but entered an elliptical orbit due to a launch vehicle error.
  • Calsphere 2 was successfully launched in 1965 on a Thor-DSV2A Able-Star sharing the flight with the Transit-O 5 navigational satellite and some small payloads.
  • Calsphere 3 and 4 were launched together on a Thor-DM21 Agena-D mission, sharing the launch with four Poppy 7 SIGINT satellites and a number of small satellites.
Nation: USA
Type / Application: Radar calibration
Operator: Naval Research Laboratory (NRL)
Contractors: Naval Research Laboratory (NRL)
Equipment: None
Configuration: Sphere
Propulsion: None
Power: None
Lifetime: Passive
Mass: 1.4 kg (#1); 4 kg (#2); 4.5 kg (#3); 5 kg (#4)
Orbit: 231 km × 2748 km, 70.34 (#1); 1083 km × 1194 km, 90.04 (#2); 913 km × 936 km, 69.97 (#3); 914 km × 925 km, 69.98 (#4)
Satellite COSPAR Date LS Launch Vehicle Remarks
Calsphere 1 1962 βτ 5 13.12.1962 Va 75-1-1 P Thor-DM21 Agena-D with Poppy 3A, Poppy 3B, Injun 3, Surcal 2, Wild Bill 2
Calsphere 2 (NRL-PL 158 ?) 1965-065H 13.08.1965 Va 75-1-1 Thor-DSV2A Able-Star with Transit-O 5, Long Rod, Tempsat 1, Dodecapole 2, Surcal 5
Calsphere 3 (NRL-PL 160) 1967-053A 31.05.1967 Va SLC-2W Thor-DM21 Agena-D with Poppy 7A, Poppy 7B (GGSE 4), Poppy 7C, Poppy 7D (GGSE 5), Timation 1, Calsphere 4, NRL-PL 150B, OPS 5712
Calsphere 4 (NRL-PL 159) 1967-053F 31.05.1967 Va SLC-2W Thor-DM21 Agena-D with Poppy 7A, Poppy 7B (GGSE 4), Poppy 7C, Poppy 7D (GGSE 5), Timation 1, Calsphere 3, NRL-PL 150B, OPS 5712

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