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GGTS 1, 2


GGTS (Gravity Gradient Test Satellite) were two experimental satellites to investigate gravity gradient stabilization in geostationary orbits. They were each launched together with 7 IDCSP communications satellites. The GGTS satellites used the same bus as the IDCSP, but were battery powered.

The Magnetically Anchored Gravity Systems (MACS) used to stabilize the GGTS satellite consists of two identical subsystem packages, each containing an extensible rod unit and a magnetically anchored spherical viscous damper. When the rod units are extended to the full rod length of 15.8 m. the 5 kg damper tip weights provide a symmetric dumbbell configuration. The total weight of the stabilization system is 12 kg.

The General Electric magnetically anchored viscous damper consists of two concentric spheres separated by a viscous damping fluid. The internal sphere contains a hollow cylindrical magnet which serves to "anchor' the inner sphere to the earth's magnetic field.

GGTS 1 was successfully launched on a Titan-3C into near geosynchronous orbit. It was hoped, that within 60 days after launch the satellite would reach a stabilization of 8 on the x- and y-axis. The results were compromised, as one of the dampers was magnetically contaminated.

The GGTS 2 mission was lost due to a launch vehicle failure.

Nation: USA
Type / Application: Technology, gravity gradient stabilization
Operator: USAF
Equipment: 2 MACS gravity gradient stabilization booms
Power: Batteries
Mass: 47 kg
Orbit: 33663 km × 33858 km, 4.2
Satellite COSPAR Date LS Launch Vehicle Remarks
GGTS 1 (OPS 9381) 1966-053A 16.06.1966 CC LC-41 Titan-3C with IDCSP 1, 2, 3, 4, 5, 6, 7
GGTS 2 1966-F08 26.08.1966 CC LC-41 F Titan-3C with IDCSP (8), (9), (10), (11), (12), (13), (14)


  • P. Weygandt, R. Moyer: Attitude Control For The Gravity Gradient Test Satellite (Abstract), 15 August 1966