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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.

Officials broke ground 10 February 2015 at the U.S. Army Garrison Kwajalein Atoll, Republic of the Marshall Islands, to kick off a 36-month construction effort to build the Space Fence radar system. The construction process is challenging due to the remoteness and cultural and historic significance of the location. The buildings are designed to handle high winds and seismic loads, while maintaining the alignment and accuracy of the radar system.

The Space Fence, an S-band radar, will be located on the U.S. Army Garrison Kwajalein Atoll, but the Space Fence Operations Center will be co-located at Reagan Test Site Operation Center in Huntsville, Ala., or ROC-H.

"The Air Force's installation of the new space fence radar marks a key milestone for both USAG-KA and RTS," said Richard DeFatta, acting director, U.S. Army Space and Missile Defense Command/Army Forces Strategic Command's Technical Center. "It brings another significant tenant to the garrison, but will also allow the range to explore cooperative opportunities to work with the Air Force in SMDC/ARSTRAT's critical space operational mission area."

The Space Fence will provide the capability for dedicated uncued surveillance of small objects in low-earth orbit with useful capability in the higher orbit regimes. Uncued detection provides a continuous "curtain" of radar pulses forming a "fence" that enables detection, tracking and determination of objects' orbits without prior knowledge of their existence or location. The system will improve space situational awareness by detecting and tracking objects such as commercial and military satellites and debris from break-up events at a higher accuracy. Coverage will extend down to just above the horizon to handle low-inclination orbits.

The Space Fence will work in conjunction with the Joint Space Operations Center, or JSpOC, to provide an integrated picture of the space operating environment for the Warfighter.

"Previously, the Air Force could only track and identify items the size of a basketball," said Dana Whalley, the Space Fence program manager, who is stationed at Hanscom Air Force Base, Mass. "With the new system, we'll be able to identify items down to the size of a softball. This will significantly increase our capability to provide predictive and actionable space situational awareness for the nation.

"The program will provide knowledge of objects, debris and events that will help us to maintain U.S. and allied space capabilities, protect space assets and prevent potential collisions in near-earth orbit," Whalley said.

The Space Fence is designed to provide assured coverage at low earth orbit for objects as small as 10 cm. The system will also support cued searches and uncued surveillance at medium earth orbit and above. The increased Space Fence sensitivity, coupled with the increased computing capabilities of the JSpOC Mission System, will yield a greater understanding of the space operating environment and associated threats.

"By providing a better picture of the space operating environment, Space Fence will greatly improve the Air Force's ability to see and understand that battlespace," said Whalley.

Officials awarded the engineering, manufacturing and design contract valued at $914 million to Lockheed Martin on June 2. About 250 workers will live on island during the construction period, which is expected to be ongoing until February 2018. Once the construction is complete, the Air Force will begin conducting acceptance testing. The projected initial operational capability is fiscal year 2019. The contract also includes an option for procuring a second radar site.

The Space Fence will replace the Air Force Space Surveillance System, or AFSSS, which has been in service since 1961 and could track about 20,000 objects before being shut down last year. The Space Fence will expand that to 100,000 objects or more by using two strategically placed ground radars, with the first one to be located on Kwajalein and the second to be located in Australia if further procurement allows for it.

Lockheed Martin’s Space Fence System, including the large-scale digital radar and turn-key facility were deemed technically mature and provided evidence that all requirements will be met through the program’s Critical Design Review (CDR) conducted by the U.S. Air Force in September 2015.

Government representatives met with Lockheed Martin engineers in Moorestown to review the Space Fence S-band radar system design, which will detect, track, and catalog orbital objects in space more than 1.5 million times a day to predict and prevent space-based collisions. The three-day CDR was preceded by the delivery of 21,000 pages of design documents, and an eight-day Design Walkthrough, to ensure the system will meet performance requirements. The CDR event featured the demonstration of a small-scale system built with end-item components that detected and tracked orbiting space objects.

“Completion of CDR marks the end of the design phase and the start of radar production and facility construction of the Space Fence system,” says Steve Bruce, vice president for Advanced Systems at Lockheed Martin’s Mission Systems and Training business. "Once complete, Space Fence will deliver revolutionary capability to the U.S. Air Force with a flexible system capable of adapting to future missions requiring new tracking and coverage approaches. We look forward to continuing our successful partnerships with the U.S. Air Force Space and Missile Systems Center, Life-Cycle Management Center and Space Command.”

Within the Space Fence radar open architecture design, Lockheed Martin uses the latest monolithic microwave integrated circuit technology, including Gallium Nitride (GaN) semiconductor materials. GaN provides a number of significant advantages for active phased array radar systems, including higher power density, greater efficiency and significantly improved reliability over previous technologies.

Lockheed Martin has a decade of investment and significant experience in successfully developing GaN-based products. Lockheed Martin is able to procure mature technology that is commercially available, aided by significant investment occurring in the marketplace in areas such as cell phone infrastructure and LED design. This is in alignment with the recent release of Better Buying power 3.0 and the need to leverage commercial technology where applicable to lower development costs and provide greater value for the Department of Defense.

The sensor site installation will include an on-site operations center and an annex to the current island power plant that will ensure the Space Fence system has everything necessary to provide continuous Space Situational Awareness. Once construction is complete, Space Fence will go through testing and validation before its initial operating capability occurs in late 2018.

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