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Space Fence (AFSSS S-Band)

The Space Fence (formerly Air Force Space Surveillance System S-Band Radar) program provides a radar system operating in the S-band frequency range to replace the AFSSS VHF "Fence" radar that currently performs detection of orbiting space objects. The Space Fence will have a modern, net-centric architecture that is capable of detecting much smaller objects in low/medium Earth orbit (LEO/MEO). The system will operate with greater accuracy and timeliness to meet warfighter requirements for Space Situational Awareness.

The existing Air Force Space Surveillance System (AFSSS) is also known as the "Fence" because several transmitters and receivers create a narrow, continent- wide planar energy field in space. Satellites passing through the energy field or "Fence" can be detected. The "Fence" mission is: to maintain a constant surveillance of space and provide satellite data as directed by US Strategic Command, to fulfill national requirements.

The nine (9) FENCE sites were located on a path across the southern United States from Georgia to California along the 33rd parallel and consist of three (3) transmitter and six (6) receiver sites. The main transmitting station located at Lake Kickapoo, Texas, has an average power output of 766,800 watts feeding a two-mile long antenna array. It provides the primary source of illumination. Two other transmitting stations are located at Jordan Lake, Alabama, and Gila River, Arizona. These stations, with average power output of approximately 40,000 watts each, improve low altitude illumination at the sides of the main beam. Receiving stations are located at Tattnall, Georgia; Hawkinsville, Georgia; Silver Lake, Mississippi; Red River, Arkansas; Elephant Butte, New Mexico; and San Diego, California. The stations at Hawkinsville and Elephant Butte have larger antennas for high altitude detection in addition to low earth capability. Energy emitted from the transmitter sites forms a fixed position, very narrow, fan shaped beam in the north-south direction extending across the continental United States in the east-west direction. One or more of the receiver sites receives energy reflected from objects penetrating the beam.

HQ AFSPC conducts the surveillance mission through three operational functions. First, a network of three transmitter and six receiver stations located on a great circle across the southern United States performs data acquisition of a satellite radar reflection. Next, data from the surveillance system is transmitted via a communications network back to the Mission Processing System (MPS) in Dahlgren, Virginia. In the processing center, computers perform satellite detection and correlation with predictions. Finally, the MPS stores, retrieves, and updates orbital elements for all orbital objects that can be detected by the AFSSS and other sensors.

The end product is a backup product is backup catalog consisting of currently over 9,000 objects that will be used as necessary during Alternate Space Control Center (ASCC) activations. Satellite detections are also reported to the 1st Space Control Squadron as a sensor input into the SCC catalog. The catalogs are a database of orbital elements from which it is possible to calculate position and velocity at any time for any satellite in Earth orbit. Predicted positions of these objects are essential data for all analyses, including threat assessments. Satellite detection by other space surveillance assets are similarly reported to Dahlgren and are incorporated into the process that generates the HQ AFSPC backup catalog.

ESC is conducting a Concept Studies Phase, including a Risk Reduction contract effort, during the FY05 to FY07 time period. The follow-on system development, production, and fielding phases are expected to begin in FY08, with development contract award early that year. Delivery of the Initial Operational Capability (IOC) is expected in the FY13-14 time frame.

The contractor shall provide non-personal services to manage, operate and maintain the nine (9) AN/FPS-133 sites (otherwise known as the FENCE) to provide uninterrupted space surveillance resulting in automated data transmission to the Computational Center (DCC) located in Dahlgren VA. The FENCE system has been identified as a critical defense system and, therefore, shall be manned 24-hours a day, 7 days-a-week, 365 days-a-year (24/7). Further, the contractor shall continue to operate and maintain the system in the event of a national emergency, to include declared or undeclared state of war.

On 01 May 2007 the Government released an initial draft Space Fence System Performance Specification and Facility Requirements Document (FRD) for industry review. The Government intends that the specification should contain requirements written primarily at the system level and as performance requirements, rather than design requirements, to provide industry with as much flexibility as possible in proposing a cost effective solution with the highest mission utility. The Government desires industry feedback and suggestions that would improve the specification's performance requirements, especially in the areas of object detection, fence integrity, and radar coverage. The Government desires specific feedback on the utility of potential frequency bands and the availability of spectrum allocations at likely Space Fence overseas sites (see the AFSPC Space Fence Siting Study), to assist in development of the specification and overall acquisition strategy. To provide an affordable program with immediate mission utility, the Government expects to acquire the Space Fence though an incremental, block approach with each succeeding block providing more system capability (e.g., number of sites, performance, functionality). The Government desires industry feedback on a viable block approach and schedule, potential block content, and required funding, to assist in development of the overall acquisition strategy.

The following companies responded to the RFI:

  • Lockheed Martin Maritime Systems & Sensors
  • Raytheon Integrated Defense Systems, Surveillance and Sensor Systems
  • Northrop Grumman Corporation, Electronic Systems
  • Analytical Graphics Inc.
The Air Force asked Congress for $4 million for the Space Fence in 2008, about $10 million less than envisioned in the out-year spending plan that accompanied the service's 2007 request. For subsequent years, the gap between the two funding profiles for the Space Fence is even wider. Last year's projections for 2009 and 2010 were $75 million and $106.5 million, respectively. The revised projections for those years are $13.9 million and $65.6 million, respectively.

The new system uses S-band ground-based radar and will replace a 1960s-era system used by the US Air Force to monitor satellites and space debris. Construction began in February 2015 on the nearly $1.5 billion radar system located on the Kwajalein Atoll, where the United States has a military installation including a Ballistic Missile Defense test site.

When it comes online in 2018, Space Fence will enable the Air Force to locate and track hundreds of thousands of objects orbiting Earth with more precision than ever before to help reduce the potential for collisions with critical space-based infrastructure.

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