Mercury 14, 15, 16 ('Advanced Vortex 1, 2, 3')

The Mercury (MC) series, although known to the public as 'Advanced Vortex', are the latest generation of USAF ELINT/SIGINT satellites. They were focussed on communications intelligence (COMINT), focused at strategic level communications, but had the capability added to intercept also missile telemetry. These satellites were launched under the designation Mission 7500 and were part of NRO's Program A.

Unlike their predecessors of the Canyon and Chalet / Vortex series, they are operated from a true geostationary orbit. The satellites of this series were injected directly into the final orbit by the launch vehicle's upper stage, so they did not feature an apogee propulsion system.

They consist of a large antenna and are three axis stabilized. These satelites have the capability to geolocate a stationary emitter if itss signal is collected by two of the systems satellites simultaneously. The collected data is digitized, encrypted and downlicked to the RAF Menwith Hill Station, UK. The satellites have the capability to be repositioned along the geostationary arc as required.

The Mercury satellites have the primary mission to collect strategic and tactical military, scientific, politicla and economic communication signals with the focus on high-capacity microwave emitters. As a secondary mission, they also collect against ELINT (primary TECHELINT), Command & Control (RUTLEY) transmissions, pulse position modulator and pulse code modulation signals from missile guidance systems, machine-to-machine (PROFORMA) transmissions, FISINT, Russian short range air navigation system (RSBN), troposcatter emitters, Search & Rescue (SAR) emitters and cellular telephon signals.

The satellites were operated from Menwith Hill, UK.

Mercury 14 (USA 105) was launched on 27 August 1994 on a Titan-4(01)A Centaur-T.

Mercury 15 (USA 118) was launched on 24 April 1996 on a Titan-4(01)A Centaur-T.

Mercury 16 was launched on 12 August 1998 on a Titan-4(01)A Centaur-T, but was lost in a launch failure, caused by a short circuit in the guidance system.

The COMINT capability was merged into the succeeding advanced Orion (Mission 8300) series of SIGINT satellites.

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