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Orion 3, 4

The Orion 3 and 4 (RIO 3, 4) satellites, which are generally known as 'Advanced Orion' or 'Mentor', are geostationary signals intelligence satellites, which replaced the Magnum / Orion series. Their purpose is to intercept missile telemetry from Russia and China and the COMINT capability of the Mercury satellites was merged into this series. These satellites are launched under the designation Mission 7600.

Although this satellite series was originally designed for FISINT (Foreign Instrumentation Signals Intelligence), they are now primarily used as COMINT collectors, with about 85% of their work is againt COMINT targets. Some were collocated with Thuraya mobile communications satellites.

These satellites feature a large dish antenna for signal reception, which has reportedly a diameter of ~100 m. The main body has the shape of an octagonal prism, carrying an large array of different antennas, among them a smaller deployable dish. The combination of fixed and steerable feeds allows simultaneous collection againt multiple signal types (COMINT, ELINT, MASINT, etc.) located across a broad geographic aera. The satellites of this series are injected directly into the final orbit by the launch vehicle's upper stage, so they do not feature an apogee propulsion system. These satellites have a significantly larger mass as the first two Magnum / Orion satellites.

Additionally to the SIGINT task, these satellites reportedly also included a communications cross-link system in space and had some limited data relay capability, which they inherited from the aborted project Kodiak.

Orion 3 (USA 1108) was launched on 14 May 1995 on a Titan-4(01)A Centaur-T rocket. It was initially positioned around 90-91 East and moved to 121 East in 1996-99. Since 2009 it has been at the 127 East position.

Orion 4 (USA 139) was launched on 9 May 1998 on a Titan-4(01)B Centaur-T.

Orion-3 is operated from the Pine Gap, Australia, ground station, while Orion-4 is operated from Menwith Hill, UK.

These satellites were succeded by the Mision 8300 Orion satellites, which unified the capabilities of Orion (Mission 7600) and Mercury (Mission 7500).

Note: The NROL designations refer to the launch, not to the payload.

Nation: USA
Type / Application: SIGINT, ELINT, COMINT
Operator: NRO, CIA, NSA
Contractors: TRW
Equipment: ?
Configuration: Large Dish Antenna, 3-Axis-Stabilization
Propulsion: ?
Power: Solar arrays, batteries
Lifetime: ?
Mass: 4500-5200 kg
Orbit: GEO
Satellite COSPAR Date LS Launch Vehicle Remarks
Orion 3 (RIO 3, Mission 7607, USA 110) 1995-022A 14.05.1995 CC LC-40 Titan-4(01)A Centaur-T
Orion 4 (RIO 4, Mission 7608 ?, USA 139, NROL 6) 1998-029A 09.05.1998 CC LC-40 Titan-4(01)B Centaur-T


Further high orbit SIGINT missions:

Geostationary orbit COMINT (Canyon-Chalet-Vortex-Mercury series) Geostationary orbit SIGINT (Rhyolite-Aquacade-Magnum-Orion series) High elliptical orbit SIGINT (Jumpseat-Trumpet series) Other high orbit SIGINT

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