Space is big. Objects in space are very dangerous to each other. Countries that intend to launch objects into space need to know what’s out there, in order to avoid disasters like the 2009 collision of 2 orbital satellites. All they need to do is track many thousands of man-made space objects, traveling at about 9 times the speed of a bullet, and residing in a search area that’s 220,000 times the volume of Earth’s oceans.
The US Air Force Materiel Command’s Electronic Systems Center at Hanscom Air Force Base in Massachusetts leads the procurement for the USA’s Space Fence, which is intended to improve space situational awareness as legacy systems in the Space Surveillance Network (SSN) are retired. With a total anticipated value of around $6.1 billion over its lifetime, Space Fence will deliver a system of 2-3 geographically dispersed ground-based radars to provide timely assessment of space objects, events, and debris.
The Space Fence program will provide a radar system operating in the S-band frequency range to replace the Air Force Space Surveillance System (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). It was slated to go live by 2015, but current GAO reports believe this will be 2017 at the earliest.
In 1980, there were 5,396 total objects to track. In 2010, there were 15,639. Space Fence is expected to grow that set very quickly, because the higher wave frequency of the new Space Fence radars will allow for the detection of much smaller microsatellites and debris than the current systems allow. At the same time, global political and technology trends are accelerating the absolute number of these objects in space.
The current AFSSS is also known as a “fence” because several transmitters and receivers create a narrow, continent-wide planar energy field in space. There are currently 9 AFSSS sites (3 transmitter, 6 receiver), located on a path across the southern United States from Georgia to California along the 33rd parallel. 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.
The new Space Fence system would reduce the number of sites to 2 or 3. John Morse, Space Fence Program Manager, Lockheed Martin MS2 Radar Systems:
“The new Space Fence will be located in geographically dispersed areas to give us better coverage in the Southern Hemisphere in particular. It will also enhance the space situational awareness by being able to see smaller objects….Space Fence will be a system of systems that consists of 2 to 3 large S-band radars and those radars will join other sensors in the space surveillance network and provide space situational awareness to the Air Force….The scope of the Space Fence contract includes sensors, mission processing, data processing, facilities, and communications, the whole system requirement….In order to use the space domain, we need to have accurate space situational awareness….We need to know where things are so we can use space when and how we need to use it. So the military application can be summed as giving the Air Force enhanced space situational awareness.”
The Space Fence procurement is broken down into the following phases: Phase A, Preliminary Design Review, System Development, Deployment and Follow-on support. System development is scheduled to begin in June 2012, with the first Space Fence radar site providing initial operational capability by the end of fiscal year 2015, and the final site providing full capability by 2020.
To fit this program into its larger context, the US GAO characterized 4 facets of space situational awareness (SSA), an umbrella term that includes but it not limited to tracking space debris:
Detect, Track, and Identify. The ability to discover, track, and differentiate among space objects. Space Fence will anchor this facet, but it won’t be the only asset used for this purpose.
Threat warning and Assessment. The ability to predict and differentiate among potential or actual attacks, space weather environment effects, and space system anomalies. Space Fence may be able to help with this task, but in a secondary way.
Intelligence characterization. The ability to determine performance and characteristics of current and future foreign space and counterspace system capabilities, as well as foreign adversary intentions. Better monitoring of space may help with intelligence collection, but in a tertiary way.
Data integration. The ability to correlate and integrate multisource data into a single common operational picture and enable dynamic decision making. Out of scope for Space Fence. The USA’s pending Joint Space Operations Center Mission System (JMS) will play a large role here, and must be ready, or the amount of data generated by the new radars will exceed the system’s capacity.
Over the 2011-2015 period, Pentagon expects about 66% of their $3.3 billion SSA investment to buy new sensors, about 21% on JMS for data integration, and the other 13% on extending the lives of current sensors, and other SSA-related programs.
At an estimated program cost of $6.1 billion over its lifetime, Space Fence will be the USAF’s largest single investment in SSA sensors. It will serve alongside new systems like the SSBS satellite, the pending ground-based RAIDRS electromagnetic interference detection system, and DARPA’s pending ground-based Space Surveillance Telescope. They’re designed to boost the existing Space Surveillance Network, which includes 29 ground-based Department of Defense (DOD) and privately/foreign owned radar and optical sensors, at 17 worldwide locations; plus a communications network, and primary and alternate operations centers for data processing. Most of the sensors are mechanical tracking, phased-array, and continuous-wave radars, but optical telescopes are also used.