Ballistic Missile Early Warning System (BMEWS)


This photo, and the note below is post 1996, after the AN/FPS-49 tracking radar was replaced with the Phased Array system.


The following was contributed by James Bollinger, NCOIC, Unmanned Threat Systems, 353 CTS/RD

Another element of the missile warning and space surveillance system is the Ballistic Missile Early Warning System (BMEWS). The primary mission of BMEWS is to provide NORAD with Tactical Warning/Attack Assessment (TW/AA) data on all ICBMs and SLBMs penetrating the site's coverage. The secondary mission is to provide NORAD with Launch and Impact (L&I) predictions for attack assessment by NORAD.

Ballistic Missile Early Warning System - BMEWS - The BMEWS sensors consist of an AN/FPS- 120 two-faced phased array radars located at Thule AB, Greenland. Three AN/FPS-50V detection radars, an AN/FPS-92 tracking radar at Clear AFS, AK, and an AN/FPS- 126 three faced phased array radar at Royal Air Force (RAF) Fylingdales, United Kingdom.

2E4XI personnel are utilized at sites I and II as Quality Assurance Evaluators.

Thule Air Base is located 700 miles north of the Arctic Circle. The unit there manages and operates the AN/FPS-120 model solid state phased array radar or SSPAR for short. The radar became operational June 24, 1987, replacing the old system, which was in use for more than a quarter of a century-

Thule (Site 1) was the first UHF phased array radar designed for BMEWS ICBM warning. This dual-faced phased array radar contains 3169 antenna elements per face of which 2560 per face transmit and receive RF energy. Each array provides 870 kW of RF power. The arrays receive target returns, which are processed by the signal processors and sent to the prime mission computers for final processing and transmission to forward users.

The unit is responsible for providing tactical warning and attack assessment of a ballistic missile attack against the continental United States and southern Canada. Located at the most northern US base, it would also provide attack assessment and detection in the event of a sea launched ballistic missile attack.

Warning data from the unit is forwarded to the North American Aerospace Defense Command, Cheyenne Mountain Air Force Base, Co. The squadron is also responsible for a portion of the Air Force Space Command Space Surveillance Program and assists in tracking more than 7,000 Space objects currently in Earth's orbit. The SSPARS radar beams can reach out for approximately 3,000 nautical miles in a 240 sweep, and at this extreme range can detect an object in space the size of a small automobile. The radar is capable of detecting smaller objects at closer range.

Clear Air Force Station, Alaska (BMEWS Site II) is 40 miles north of Mount McKinley and 80 miles south of Fairbanks. It manages and operates three AN/FPS-50 detection radars (DR) that cover 120 degrees in azimuth and approximately 3000 nautical miles in range. It also supports a AN/FPS-92 tracking radar (TR).

Each AN/FPS-50 detection radar consists of three antennas and associated equipment, which monitors three areas; each area is 40 in azimuth. The DR antennas are 165 feet high by 400 feet long. They continuously watch a fixed area of space for missile launches and orbiting satellites. Radar beams at two elevation angles repetitively scan each of the DR areas. The upper radar fans radiate at 7.0 elevation and the lower radar at 3.5 elevation.

The AN/FPS-92 tracking radar is a mechanical antenna 84 feet in diameter, housed in a 140 foot high radome. Radar signals are sent out and processed for targets. This radar also performs space surveillance functions.

The unit is responsible for providing tactical warning and attack assessment of a ballistic missile attack against the continental United States and southern Canada. Warning data from the unit is forwarded to the North American Aerospace Defense Command inside Cheyenne Mountain Air Force Base, Co. The squadron is also responsible for a portion of the Air Force Space Command Space Surveillance Program and assists in tracking more than 7,000 Space objects currently in Earth's orbit. Prime power at Clear Air Force station is obtained from the station's coal fired power plant, which is capable of producing 22.5 megawatts of power.

Clear AFS's detection radars (DRs) consist of transmitters, reflectors, receivers, and the Detection Radar Data Take Of f (DRDTO). The transmitters supply two 4 megawatt beams (upper and lower) of RF energy to each of the DR reflectors. The reflectors are positioned to reflect the lower beams at 3.5 degrees elevation and the upper beams at 7.0 degrees elevation. The reflectors receive target returns, which are routed to the receiver channel for amplification. The signals are then routed to the DRDTO, which performs analog to digital conversion. The signals are next processed by the mission computers and sent to forward users. The Clear AN/FPS-92 tracking radar utilizes multiple transmitters to supply 8 megawatts of RF energy to an 84 foot diameter parabolic dish antenna. Target returns are processed in much the same way as those of the detection radar.

The Fylingdales phased array radar (Site III) became operational in 1992. With the exception of the additional array face, it has many of the same features of the Thule system.

Operational functions peculiar to this mission include:

  1. Detection and reporting, as either correlated or unknown objects, of all objects passing within normal coverage.
  2. Tracking of all space objects at a nominal range, selected satellites at extended ranges (low signal-to-noise (S/N) track), and special satellites to synchronous altitude and geosynchronous altitude.
  3. Space Object Identification (SOI) employing Automatic Pattern Recognition and high data rate collection with selective transmission of data to the SOI center.
  4. interface with Naval Space Surveillance (NAVSPASUR) for hand-off and tracking of unknown objects approaching from the north.
  5. Tracking of all domestic missile and satellite launches within coverage