NRO/USAF/NSA, SIGINT Spacecraft
By © Charles P. Vick 2007 All Rights Reserved
MERCURY-Advanced Vortex - SIGINT Spacecraft Series – (NRO/USAF/NSA - Program AFP-???)
Code name MECURY 1-3 was the new unified one serves all SIGINT satellite design successor to the Vortex series the next in a long series of earth orbit NRO/USAF/NSA, SIGINT (signals intelligence) spacecraft used by the CIA/USAF and intelligence Community for a variety of mission. They were launched by the Titan-4A Centaur booster with a total of three MERCURY 1-3 successful launches identified. The spacecraft were actually nothing more than USAF/NSA mission specific sophisticated earth orbit space based earth receiving stations operating over the entire emitted electro magnetic radio spectrum frequency range. The MERCURY 1-3 spacecraft introduced the very large unfurling dish structures “wrap-rib” large deployable bleached white gold colored mesh covered receiving dish antenna design of about 328-344.5 (312) feet in diameter with a total spacecraft estimated mass of about 9,938- 10,000 pounds for the Titan-4A Centaur. MERCURY’s first launch was August 27, 1994 and the second subsequent launch was April 24, 1996 while its third and last launch was on August 12, 1998. Earlier suggestions of the use of the Hughes satellite antenna technology is now not believed to have been adopted by the NRO due to mass constraints verses the lighter “wrap-rib” technology approach.
The MERCURY 1-3 series were designed to monitor and pick up from the ground and in flight electronic signals intelligence (ELINT), radio, communications intelligence (COMINT) and radar emitters emissions intelligence (RADINT) in addition to the primary missile test telemetry intelligence (TELINT) acquisitions capabilities all coming under the general SIGINT heading. They were fully dedicated mission operations that were highly successful in acquiring SIGINT through the larger mission general SIGINT “wrap-rib” white gold colored mesh covered reflector dishes. Its primary mission was communications intelligence (COMINT), radar emitters emissions intelligence (RADINT) and to monitor and pick up from the ground and in flight electronic signals intelligence (ELINT).
The technology for these SIGINT spacecraft fulfilled the need for larger more sophisticated systems able to do multiple missions at the same time. The technology for these SIGINT spacecraft were slow in coming on line development wise but later proved out highly successfully once the technology was perfected. Like any new technology program it had its issues that slowed its preparation for launch as the missions were revised. With this and the MENTOR and TRUMPET satellites were the new unified consolidated one serves all SIGINT satellite design for the total intelligence community requirements.
Each gravity gradient stabilized spacecraft was about 312 feet in diameter with the dish attached to gimbals for steering from the command, communication, control and intelligence, power bus. The MERCURY dish did not cover the entire visible surface of the earth but covered more than its VOIRTEX predecessor and thus the dishes were presumable set on gimbals to monitor specific points or objects of interest such as ballistic missile flight test telemetry. This would thus require several spacecraft to accomplish this monitoring task over the full range of the ICBM’s flight test.
It is presumed that each spacecraft rear bus carried one or two solar arrays with at least one down link communications dish each. The large SIGINT spacecraft was carried into earth orbit by the TITAN-4A Centaur in its shorter 76/77.73 foot long by 16.67 foot diameter payload Shroud. Part of the spacecraft which housed the forward bus mounted sophisticated receiving feed horns with log periodic antennas collecting the earth based signals reflected off the larger “Wrap-Ribbed” supported white gold mesh covered SIGINT dish. These log periodic antenna farms were also located just above spacecraft rear bus in the hub area.
Note: For further details of the Titan-4 design payload encapsulation configuration see the accompanying illustration of the payload arrangement and the feed horn log periodic details.
It is not believed that this spacecraft series carried any early warning or sophisticated infrared sensors tracking sensors like those carried on the USAF based TRUMPET, SIGINT satellites.
This spacecraft utilized the 14.5 foot diameter by 29.3 foot long Centaur-G stage to place the spacecraft on a geosynchronous transfer orbit that then became a geosynchronous orbit once the Centaur-G stage fired a second time and later the spacecraft bus housed orbital maneuvering engine was fired to placed it in that kind of a GEO orbital position. They were operated at an inclination that was at approximately near 0 degrees with a geosynchronous earth orbit (GEO) with a spacecraft life of eight to twelve years. The USAF/NSA primarily utilized it for monitoring Soviet missile test flights operations telemetry traffic emissions.
The Centaur-G rocket stage portion of the SIGINT packages carried the usual assortment of earth, horizon and solar sensors to orient the spacecraft but it did not remain attached to the spacecraft. The constellation of spacecraft was able to receive and send the data to several global ground stations via radio signal operated by NSA/CIA personnel. The data was then processed and analyzed at NSA headquarters for further analysis distribution to the USAF intelligence community. The spacecraft series cost rose from $1,750,000.00 each with a launch cost initially at $430,000,000.00 each.
1. McDowell, Jonathan, http://www.planet4589.org/space/ web site satellite information tables.
2. Guillemette, Roger G, Top –Secret Eavesdropping Satellite Launched by Titan IV/Centaur, Countdown, July/August, 1994, page 39-35
3. Guillemette, Roger G, USAF Launches Pair of Top-Secret Eavesdropping Satellites but Titan-IV Suffers Yet Another Setback, Countdown, September/October, 1995, pp. 28-25.
The MERCURY signals intelligence spacecraft are designed to intercept transmissions from broadcast communications systems such as radios, as well as radars and other electronic systems. The interception of such transmissions can provide information on the type and location of even low power transmitters, such as hand-held radios. The MERCURY [Advanced VORTEX] spacecraft is believed to be built by Hughes, and to utilize a much larger military version of the special antenna that will be used on the commercial APMT mobile communications system.
Signals intelligence (SIGINT) consists of several categories. The VORTEX Communications intelligence (COMINT) system was originally developed by the Air Force for NRO to support NSA collection and exploitation of intercepted message traffic. The first CHALET spacecraft [as VORTEX was originally known] were first orbited in the late 1970's, and had an antenna with a diameter of several tens of meters. The most recent Advanced VORTEX spacecraft, since renamed MERCURY, have a very large deployable antennae with a diameter of approximately 100 meters. With the consolidation of all SIGINT programs under the NRO SIGINT Directorate, MERCURY has been redirected to additionally perform Electronic intelligence (ELINT) collection of non-communications electronic transmissions, to includ telemetry from missile tests (TELINT), or radar transmitters (RADINT).
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