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.
Note: The NROL designations refer to the launch, not to the payload.
|Type / Application:||SIGINT, ELINT, COMINT|
|Operator:||NRO, CIA, NSA|
|Configuration:||Large Dish Antenna, 3-Axis-Stabilization|
|Power:||Solar arrays, batteries|
|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|