Space Fence

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Diagram of the Space Fence

The Space Fence is a second-generation space surveillance system operated by the United States Space Force in order to track artificial satellites and space debris in Earth orbit.[1]

Contracts were issued for development and construction in 2014, and the Space Fence was expected to be operational in the fourth quarter of 2019.[1][2] The budget is US$1.594 billion (FY15).[3]

The initial space fence facility was to be located at Kwajalein Atoll in the Marshall Islands,[1] along with an option for another radar site in Western Australia.[2][4]

The U.S. Space Force declared the system operational on March 28, 2020.[5]


Deputy Commander of Air Force Space Command, accepts a model of the Space Fence radar site at Peterson Air Force Base.

The initial plans to upgrade the legacy Air Force Space Surveillance System were made in 2009. The USAF 850th Electronic Systems Group, Electronic Systems Center awarded three $30-million study contracts to Lockheed Martin, Northrop Grumman, and Raytheon on 11 June 2009.[6]

The new Space Fence was envisioned to be a system of two or three S-band ground-based radars designed to perform uncued detection, tracking and accurate measurement of orbiting space objects, and was intended to replace the Air Force Space Surveillance System, or VHF Fence, that was transferred from the US Navy to the US Air Force in 2004. The shorter wavelength of the S-band Space Fence will allow for the detection of much smaller satellites and debris.[6]

The February 10, 2009 collision of the Iridium 33 and Cosmos 2251 communications satellites, which added hundreds more pieces of debris in orbit, highlighted the need for more precise tracking of space objects.[7]

As of 2009, data collected from the new Space Fence's sensors was planned to feed into the Joint Space Operations Center Mission System, which is used to track objects orbiting the Earth, monitor space weather, and assess foreign launches. Used by operators at the USAF 614th Air and Space Operations Center at Vandenberg Air Force Base, Calif., the 614 AOC's 24-hour-a-day, seven-day-a-week support provides vigilance of global and theater operations, and equips the Joint Functional Component Command for space operations with the tools to conduct command and control of space forces.[6]

Plans to award the final contract were delayed by the federal government's budget sequestration in early 2013[8] and the AFSSS system was scheduled to be discontinued in October 2013 due to budget cuts.[9]

In 2014, Lockheed Martin awarded a contract for the Space Fence ground structures to General Dynamics. The ground structures include the receive array, cooling equipment, radomes and other buildings. The primary Space Fence system, procured by the Air Force will be located on Kwajalein Atoll in the Marshall Islands.

The U. S. Space Force declared the system operational on March 28, 2020.[5]

Technical characteristics[edit]

The Space Fence will use S-band radar and will track a larger number of small objects than previous space radars: "about 200,000 objects and make 1.5 million observations per day, about 10 times the number" made by existing or recently retired US assets.[1]

Data-sharing agreements[edit]

As of November 2014, the United States Strategic Command had "announced data-sharing agreements with at least seven countries and 44 companies, but [the details of] those agreements have [not] been made public" and it is unclear how much of the new Space Fence data will be shared.[1]

Countries with space situational awareness data-sharing agreements in place with the USAF include Australia, Japan, Italy, Canada, France, South Korea, and the United Kingdom. It also "has agreements with the European Space Agency and Europe’s Eumetsat weather satellite organization."[1]

Predecessor system[edit]

A previous system used by the USAF for the same purpose was the Air Force Space Surveillance System, which ceased operation in September 2013.[4]


  1. ^ a b c d e f Gruss, Mike (2014-11-21). "Haney: U.S. Partners To Have Indirect Access to Space Fence Data". Space News. Archived from the original on December 1, 2014. Retrieved 2014-12-01.
  2. ^ a b Indian anti-satellite test proves early test for Space Fence, by Debra Werner — April 11, 2019,, ...Still in testing mode, the U.S. Air Force Space Fence on Kwajalein Atoll detected India’s March 27 anti-satellite test and issued a break-up alert...The Air Force is scheduled to begin initial the fourth quarter of this year...
  3. ^ "GAO-15-342SP DEFENSE ACQUISITIONS Assessments of Selected Weapon Programs" (PDF). US Government Accountability Office. March 2015. p. 125. Retrieved 16 July 2015.
  4. ^ a b Clark, Stephen (2014-06-02). "Lockheed Martin wins contract for Space Fence". Spaceflight Now. Retrieved 2014-12-01.
  5. ^ a b Erwin, Sandra (March 28, 2020). "Space Fence surveillance Radar Site Declared Operational". Retrieved March 29, 2020.
  6. ^ a b c Morales, Monica D. (July 30, 2009). "Space Fence program awards contracts for concept development". USAF News. Archived from the original on March 4, 2016. Retrieved September 13, 2014.
  7. ^ Iannotta, Becky (February 22, 2009). "U.S. Satellite Destroyed in Space Collision". Archived from the original on 13 February 2009. Retrieved 2 November 2016.
  8. ^ Ewalt, David M. (July 17, 2013). "Budget Cuts Threaten The Air Force's New 'Space Fence'". Retrieved September 13, 2014.
  9. ^ "Air Force Space Command to discontinue space surveillance system". US Air Force News. August 13, 2013. Retrieved September 13, 2014.