Advanced Extremely High Frequency (AEHF) Military Communications Satellite

Air Force Space Command announced that the Advanced Extremely High Frequency system had achieved initial operational capability on July 28, 2015. With the IOC declaration, the 4th Space Operations Squadron then started operating the AEHF system, supporting warfighters around the world.

The system will consist of five satellites in geosynchronous earth orbit (GEO) that provides 10 times the throughput of the 1990s-era Milstar satellites with a substantial increase in coverage for users. First launched in late 2010, AEHF provides continuous 24-hour coverage between 65 degrees north and 65 degrees south latitude. The AEHF system is composed of three segments: space (the satellites), ground (mission control and associated communications links) and terminals (the users). The segments will provide communications in a specified set of data rates from 75 bps to approximately 8 Mbps.

The space segment consists of a cross-linked constellation of five planned satellites as well as the five legacy Milstar satellites. The mission control segment controls satellites on orbit, monitors satellite health and provides communications system planning and monitoring. This segment is highly survivable, with both fixed and mobile control stations. System uplinks and crosslinks will operate in the extremely high frequency (EHF) range and downlinks in the super high frequency (SHF) range. The terminal segment includes fixed and ground mobile terminals, ship and submarine terminals, and airborne terminals used by all of the Services and international partners (Canada, Netherlands and UK).

The Advanced Extremely High Frequency system was one of the satellite systems projected to replace Milstar and would provide 12 times the throughput of that system. Single user’s data rates would increase dramatically, more than four times that of Milstar. So for every one link of the old Milstar, the Air Force would have 12 operating at four times the speed. The upgrade was like a one-lane road being transformed into a 12-lane information Autobahn.

The Advanced Extremely High Frequency (AEHF) System was a joint service satellite communications system that provides near-worldwide, secure, survivable, and jam-resistant communications for high-priority military ground, sea, and air assets.

The Advanced Extreme High Frequency program would provide near-worldwide, secure, survivable satellite communications to support strategic and tactical forces of the United States and its international partners during all levels of conflict.

AEHF was planned to usher in a new era of cooperation and interoperability with Canada, the Netherlands, and the United Kingdom, under cooperative development partnerships. Completion of a global capability would be enabled by the first launch of the AEHF satellite, planned for April 2008. SV-1 was designed be compatible with Milstar and would complete the Milstar capability. After the launch and deployment of SV-2, both satellites would provide XDR services, enabling an entirely new suite of coverage, networking and security services to U.S. and international partners.


The AEHF System was designed as a follow-on to the Milstar system, augmenting and improving on the capabilities of Milstar and expanding the MILSATCOM architecture. The AEHF program would provide connectivity across the spectrum of mission areas, including land, air and naval warfare, special operations, strategic nuclear operations, strategic defense, theater missile defense, space operations and intelligence.

As planned the system would of consist of three satellites in geosynchronous earth orbit (GEO) providing up to 100 times the capacity of the 1990s-era Milstar satellites, servicing up to 4,000 networks and 6,000 terminals. Assuming a full constellation of three AEHF and one Transformational Satellite (TSAT), this would provide continuous 24-hour coverage between 65 degrees north and 65 degrees south latitude. AEHF would allow the National Security Council and Unified Combat Commanders to contact their tactical and strategic forces at all levels of conflict through general nuclear war and supports the attainment of information superiority.

While the AEHF is similar to Milstar, there are numerous important advances that would significantly extend MILSATCOM capabilities. AEHF can effectively emulate a Milstar satellite to allow a large, installed base of ground, shipborne and airborne terminals to immediately make use of its extensive capability. It is planned, however, to provide tremendously more capability as the XDR services are enabled in conjunction with a new and upgraded set of user ground, airborne, and shipborne terminals. The XDR services have greatly increased coverage options to allow distributed users better access to resources including:

  • Improved adaptive antennas that would cancel out the impact of enemy emitters designed to disrupt US warfighter communications
  • New narrowband services to allow Special Operations Forces and other disadvantaged users efficient access to communications
  • “Virtual satellite” control to enable war fighters to positively manage the communications resources necessary for successful engagement
  • Greatly enhanced security improvements to block theft of cryptographic information

These services were enabled by significant technological achievements. First-ever dynamically controlled uplink and downlink phased-array antennas provided global sharing of resources for a broad array of uses. The program had successfully incorporated commercial microelectronics enabling capability while reducing the weight and power of the satellite without sacrificing the essential military essence of a system and services that are unavailable in the commercial marketplace. Overall, it was planned that one AEHF satellite would outperform the entire Milstar constellation.

The AEHF was designed to provide connectivity across the spectrum of mission areas, including land, air, and naval warfare, special operations, strategic nuclear operations, strategic defense, theater missile defense, and space operations and intelligence. The AEHF System would provide warfighters with broadcasting, data networking, voice conferencing, and strategic reportback capabilities. It would also provide commanders with the advantages of near-worldwide coverage, multi-user connectivity, protected data, and ease of use. AEHF protections included anti-jam capabilities, Low Probability of Detection (LPD), a Low Probability of Intercept (LPI), and advanced encryption systems. Finally, the AEHF system is a multinational effort with international partners from the United Kingdom, the Netherlands, and Canada. These international partners would gain access to the AEHF network through their own terminals.

The AEHF system is composed of three segments: space (the satellites), terminals (the users), and mission control and associated communications links. The segments will provide communications in a specified set of data rates from 75 bps to approximately 8 Mbps. The space segment consists of a cross-linked constellation of satellites to provide worldwide coverage. The mission control segment controls satellites on orbit, monitors satellite health, and provides communications system planning and monitoring. The segment was designed to be highly survivable, with both fixed and mobile control stations. System uplinks and crosslinks would operate at extremely high frequency (EHF), and downlinks at super high frequency (SHF). The terminal segment includes fixed and mobile ground terminals, ship and submarine terminals, and airborne terminals. User terminals supported by AEHF include Secure Mobile Anti-Jam Reliable Tactical-Terminal (SMART-T), Single Channel Anti-Jam Man Portable (SCAMP), Family of Advanced Beyond Line -of -sight Terminals (FAB-T), and Navy Multiband Terminals (NMT).

Microwave and millimeter wave units for defense satellites have been extremely expensive in the past – sometimes totaling more than 20 percent of the cost of a satellite. Typical applications used these units in high quantities and they were very expensive individually – as much as $50,000 per pound.

Defense satellite systems scheduled over the next few years would include more microwave hardware than ever before. Phased arrays would use thousands of microwave modules per satellite, and some satellite constellations would consist of as many as 20-30 satellites. Without less expensive microwave hardware, some of these key Air Force mission systems had the potential to be unaffordable.

The Manufacturing Technology (ManTech) Division of the Air Force Research Laboratory’s Materials and Manufacturing Directorate, under a cost-sharing contract with Northrop Grumman, applied new forms of automated packaging Radio Frequency (RF) modules and millimeter wave units that were designed to drive down the cost, while also decreasing the size and weight of each unit. The Affordable Millimeter Wave Units (AMU) Program allowed a rapid and highly repeatable automated assembly of module and board level AMUs, with minimal labor, and no hand tuning.

AMU had successfully demonstrated hardware designed specifically for three major defense satellite system programs. Near term space systems, such as the Transformational Satellite, and the Space-Based Infrared System Low and Advanced Extremely High Frequency (AEHF) had estimates placed that show that AMU’s technologies will save 50-80 percent of the cost of tens of thousands of modules, which previously would cost several thousand dollars apiece. The AEHF, for example, had adopted and inserted AMU’s technologies in more than 100 RF board assemblies and nearly 10,000 RF modules.

The AEHF satellites are intended to directly respond to service requests from operational commanders and user terminals providing real-time point-to-point connectivity and network services on a priority basis. On-board signal processing would provide protection and ensure optimum resource utilization and system flexibility among the Military Services and other users who operate terminals on land, sea, and air. The AEHF system would be backward compatible with the low data rate (LDR) and medium data rate (MDR) capabilities of legacy Milstar satellites and terminals, while providing extended data rates (XDR) and other improved functionality at substantially less cost than the previous system. Each satellite was planned to be launched with the Evolved Expendable Launch Vehicle (EELV), with the initial launch planned for 2007. The MILSATCOM Joint Program Office (MJPO), Space and Missile Systems Center (SMC), has been responsible for development, acquisition, and sustaining of the WGS AEHF Program.

Program History

SMC awarded two competitive contracts for system definition of AEHF on 23 August 1999.

The Joint Requirements Oversight Council again validated the user community’s need 23 March 2000 for mitigating the loss of Milstar Flight 3. Flight 3, launched in April 1999, was equipped with the first medium-data-rate communications payload, which was designed to support the secure mobile antijam reliable tactical terminals performing mobile-subscriber-equipment range-extension missions at corps and division level. There was a misfire in the rocket’s upper stage, causing Flight 3 to fail to reach a useable orbit.

Since there were a number of options to mitigate Flight 3’s loss, Dr. J.S. Gansler, undersecretary of defense for acquisition and technology, signed the acquisition decision memorandum [ADM] on 6 April 2000 for the advanced extremely-high-frequency program. The ADM eliminated competition in the AEHF program and created a national team made up of Lockheed Martin, Hughes and TRW. The revised approach would provide a “Pathfinder” AEHF satellite on an accelerated schedule. Gansler’s guidance stated that Pathfinder will meet AEHF threshold requirements at a minimum and that satellites two to five would exceed threshold requirements. At that time Pathfinder was expected to launch around December 2004.

On 16 November 2001 the U.S. Air Force awarded a $2.698 billion System Development and Demonstration contract for the Advanced Extremely High Frequency satellite program to a team comprised of the Lockheed Martin Corporation, Lockheed Martin Missiles and Space, Sunnyvale, California and TRW Inc, Space and Electronics, Redondo Beach, California. The contractor team was led by Lockheed Martin as the prime integrator and provider of the Spacecraft Bus and ground command and control segments with TRW providing the satellite payload. The contract was planned to culminate in the delivery of two AEHF satellites and the ground command and control system. The first of two satellites under the contract was scheduled for launch in 2006.

The contract would develop and deliver the Department of Defense’s next generation highly secure, high capacity communications satellites and ground command and control system as a follow-on capability to DoD’s Milstar communications satellite program. AEHF would provide 10-times greater total capacity over Milstar communications satellites allowing tactical military communications such as real-time video, battlefield maps and targeting data.

On 11 October 2002, the Defense Security Cooperation Agency notified Congress of a possible Foreign Military Sale to the NATO Consultation, Command, and Control Agency (NATO NC3A) of satellite communication services and support. NATO NC3A requested a possible sale of satellite communication services and support for Extremely High Frequency (EHF) service on the United States Advanced EHF (AEHF) systems, AEHF follow-on support for meeting future satellite communication requirements, control of service-provisioned resources on AEHF and applicable follow-on systems, communications infrastructure upgrade and maintenance support, operation and logistics support including training, publications and documentation, U.S. Government and contractor technical assistance and other related requirements. The total value, if all options are exercised, was stated to be potentially as high as $550 million.

The proposed sale was in support of a competition that was limited to bids from member nations that participate in NATO. NATO remains the fundamental component of US national security in the North Atlantic and European regions. By providing satellite communication services, the US would ensure interoperability with US capabilities and those of our NATO allies and maintain a direct influence on NATO’s communications architecture.

As of 2002 NATO had a satellite communications system that was used in support of NATO military operations and to provide communications for political consultations. The proposed sale would obtain a protected satellite communications capability and augment their existing satellite communications system. NATO has been operating a satellite communications system since the early 1970’s.

In 2002 defense officials announced a 2009 target for the launch of a “transformational” SATCOM system and subsequently established an office to develop the program architecture. Officials would decide by the end of 2004 on whether to proceed with buying two more Advanced Extremely High Frequency satellites or commit to building a more advanced system reliant on laser technologies. As of late 2002 the fate of a planned five-satellite buy of the Lockheed Martin-led Advanced Extremely High Frequency satellite system depended upon the progress of the Transformational Communications System (TCS).

At least three AEHF satellites would be required to support critical military communications, and as many as five were potentially needed, depending on progress in the research and development of next-generation transformational communications satellites.

The fiscal year 2004 budget request, submitted in early 2003, included no procurement funding for the third AEHF satellite. At that time the Air Force did not intend to request funding until fiscal year 2005. This represented a significant change from the budget projection for AEHF in fiscal year 2003, when the Air Force had planned to request $95 million in advanced procurement for the third AEHF satellite in fiscal year 2004. The delay resulted in a significant production gap that required a costly requalification of suppliers, a significant increase in technical risks, and delays in the AEHF schedule.

In June 2003 Lockheed Martin Corp, Sunnyvale, California, was awarded a $5,200,000 contract modification to provide for in-scope changes to modify the Advanced Extremely High Frequency (AEHF) Payload to accommodate resources to process Rapid Reconfiguration Order Wire (RROW) AEHF Access Control Channel Uplink (XC2) streams. The technical change ensured backward compatibility with MILSTAR operations and would provide users the capability to fence the necessary payload resources to process RROW XC2 streams and the capability to control the fenced RROW XC2 stream processing payload resources as any other fenced resource, including sub-fences and sub-sub-fences, via command and access control protocol. The change would impact multiple documents, the Mission Planning Element of the Mission Control Segment, the Configurable Onboard Router in the Digital Processing Subsystem and the payload software. The AEHF Satellite Communications System provided secure, survivable communications to US warfighters during all levels of conflict and was planned to be the protected backbone of the DoD’s military satellite communications architecture. The work was not planned to be completed in September 2008.

Because the AEHF system would include devices connected to the Air Force Constellation Net, the AEHF program office engaged the Air Force Space Command Certification and Accreditation Section to ensure all network security concerns were identified and mitigated during the development of the system.

Historically, early engagement with network security subject matter experts reduced or eliminated security modifications that had to be resolved by redesign during the implementation phase of a system. It was well known that security modifications made during the implementation phase of a system are the most expensive and time consuming. Modifications required at implementation are best avoided with thorough analysis during the requirements phase. The AEHF program office was actively pursuing this objective.

On May 18, 2004 Lockheed Martin Corporation, Space Systems Company, Sunnyvale, California and Northrop Grumman Space Technology, Los Angeles, California, were awarded a $149,000,000 contract modification which incorporated within-scope changes resulting from Revision to the KI-54 Cryptographic Interface Control Document (ICD). The KI-54 ICD was modified by the NSA’s contractor, the Advanced Extremely High Frequency (AEHF) prime and subcontractor team (Lockheed Martin and Northrop Grumman) was required to redesign the Host Accessory Logic Application Specific Integrated Circuit (HAL ASIC) in the AEHF communication payload. The effort was captured in Phase 1. In Phase 2, the AEHF contractor team would receive a four months program extension to identify and mitigate the AEHF system-level risks associated with the HAL ASIC redesign. (Note: The KI-54 is an encryption device or “black box”) This change to the AEHF Technical Baseline during FY04 would allow the contractor team to proceed with the development of the AEHF program with reduced technical risk. Providing the technical change ensured that system compatibility issues with the KI-54 would be addressed in a thorough fashion to ensure mission success. Locations of performance were: Lockheed Martin Corp., Sunnyvale Calif. (51%) and Northrop Grumman, Los Angeles, California (49%). At this time, $19,812,000 of the funds has been obligated. The work was planned to be complete by September 2008.

In October 2004 the Air Force decided against buying a fourth AEHF satellite in order to proceed more quickly with the Transformational Communications Satellite (TSAT).

On 21 December 2004 the Air Force announced that the AEHF communications satellite program had suffered a schedule slip of one year, with launch of the first of three planned satellites delayed to 2008 rather than 2007, and cost growth of about 20 percent. The AEHF program experienced unavoidable delays and cost growth due to delayed delivery of information-assurance (signal-encryption) products, and the resulting delay of terminals required for satellite command and control. As a result of these schedule impacts, the AEHF program was delayed by 12 months. The AEHF program also experienced cost growth due to replacement of critical electronic parts and added payload component testing. However, these activities had schedule impact. With the restructure, the projected launches were scheduled for April 2008, April 2009 and April 2010.

The first AEHF space vehicle (SV-1) would be operated as a Milstar-only capability to complete the Milstar capability. After the launch and deployment of AEHF space vehicle 2 (SV-2), both satellites would provide extended-data-rate (XDR) services (up to 8.139 Mbps), enabling an entirely new suite of coverage, networking and security services to U.S. and international cooperative development partners Canada, the Netherlands and the United Kingdom.

The AEHF program suffered problems with two identified causes. First, the production and delivery of newly developed information-assurance products, and the resulting delay of satellite command and control terminals, had fallen behind schedule, causing satellite launches to be delayed by 12 months. Second, the program incurred cost growth from unplanned payload component testing and replacement of existing critical electronic components. These combined cost and schedule impacts were expected to increase the overall cost of the AEHF program by approximately 20 percent.

Development of new, complex information-assurance products, concurrently with other AEHF subsystems, was a technically challenging and high-risk area for the program. The National Security Agency (NSA), working closely with the MILSATCOM Joint Program Office, implemented several risk-reduction actions to sustain ongoing satellite integration and test activities. In spite of these efforts, delayed delivery of final information-assurance products and satellite command and control terminals was preventing the government from delivering them to the AEHF prime contractor, Lockheed Martin, on schedule. Late receipt of this government-furnished equipment would prevent on-time completion of AEHF system integration and test, and ultimately delay satellite launches.

The AEHF program incurred cost growth from unplanned payload component testing and replacement of existing critical electronic components with parts that could be space-qualified within schedule. While these activities contributed to the overall cost growth, they did not contribute to the schedule delays.

As of early 2005 projections of the Milstar constellation revealed a healthy constellation through the 2011-2014 timeframe. This constellation would maintain a robust low-data-rate (75 to 2,400 bits per second) capability to provide command and control to strategic forces and was one satellite shy of global medium-data-rate service (4800 bps to 1.544 megabits per second) due to the launch vehicle failure in April 1999 of the Milstar Flight 3 satellite. Completion of a global capability was planned to be enabled by the first launch of the AEHF satellite in April 2008.

Lockheed Martin, Space Systems Company, Sunnyvale, California, was awarded on 14 April 2006 a $454,882,060 cost plus fixed fee, cost plus award fee contract modification. The contract action was for the implementation of the Advanced Extremely High Frequency (AEHF) Satellite Communication System Program re-plan, which started in late 2004. The re-plan was necessary due to delayed delivery of government-furnished information assurance products, added payload component testing, and replacement of critical parts that were disqualified for space flight. The effort includes development of emulators, additional testing associated with integrating multiple incremental deliveries, and additional months of non-recurring development. The resulting AEHF first launch date of April 2008 was consistent with the revised Acquisition Program Baseline approved in March 2005. At that time, $17,709,000 had been obligated. The work was planned to be completed by May 2010.

A March 2007 Government Accountability Report stated that the AEHF program’s technologies were stable and mature, and that schedule risk came from critical items developed outside of the AEHF program itself. In the report according to the program office, the issues had been resolved and the first satellite was entering into final integration and testing and was on schedule for the first launch. Current plans were to meet full operational capability with three AEHF satellites and the first Transformational Satellite Communications System (TSAT) satellite.

Resolving the issues added approximately $800 million to the program. In 2006 the GAO reported that the program still faced schedule risk due to concurrent development of two critical path items developed and managed outside the program: the cryptographic components developed and produced by the National Security Agency and the Command Post Terminal managed by another Air Force program office.

The AEHF program office reported all cryptographic hardware and components for the satellites were delivered, meeting all revised delivery milestones as of March 2007. In addition, the replacement of critical electronic components and additional payload testing was completed.

Since the 2006 GAO assessment of the AEHF, the Command Post Terminal, a critical path item, was delayed. However, the program office intended to then use the test terminal that was originally built to provide end-to-end testing of the system to control the satellites. Program officials stated that utilizing the test terminal, developed by Lincoln Laboratories, will have no adverse schedule or operational impact on the satellites.

Program officials reported to the GAO in 2007 that the mission control segment continued to meet or exceed schedule and performance milestones. Three AEHF satellite launches were scheduled for 2008, 2009, and 2010. The program completed most systems-level testing and started final integration and environmental testing on the first satellite. The program remained on schedule, as of 2007, to meet the first launch date. The flight structure for the second satellite had also been delivered for payload integration. The third satellite was on contract and included procurement of long lead components. Full operational capability was planned with three AEHF satellites and the first TSAT.

As of the March 2007 GAO report, the Air Force stated that AEHF remained on track for a first launch date of April 2008 with events proceeding as expected in accordance with the December 2004 program replan. The Air Force further stated that the program was currently in fabrication and production of the first two satellites, and the third satellite will begin assembly, integration, and test in FY09. It noted that the cryptographic chip development remained on schedule since the January 2005 summit between the Air Force and the National Security Agency. In addition, the Air Force stated that all spacecraft flight cryptographic units were received on schedule and that chips for the ground terminals were due over the next couple of years to support terminal production schedules. Moreover, according to Air Force officials, DoD explored the option of adding a fourth AEHF satellite to mitigate the potential gap caused by schedule slips in the TSAT program, but decided to restructure the TSAT program baseline and not purchase a fourth AEHF satellite at the time.

The U.S. Air Force’s 4th Space Operations Squadron at Schriever Air Force Base began “talking” with the fifth Advanced Extremely High Frequency (AEHF-5) protected communication satellite after its successful launch from Cape Canaveral Air Force Station, Florida, Aug. 8, 2019. The Lockheed Martin-built AEHF-5 satellite was responding to the squadron’s commands as planned. The squadron began “flying” the satellite shortly after it separated from its United Launch Alliance Atlas V 551 rocket approximately 5 hours and 40 minutes after the rocket’s successful 6:13 a.m. ET liftoff.

AEHF-5 completes a geostationary ring of five satellites delivering global coverage for survivable, highly secure and protected communications for strategic command and tactical warfighters operating on ground, sea and air platforms. Besides U.S. forces, AEHF also serves international partners including Canada, the Netherlands and the United Kingdom.

“This fifth satellite adds an additional layer of flexibility for critical strategic and tactical protected communications serving the warfighter. This added resilience to the existing constellation will help ensure warfighters can connect globally to communicate and transmit data at all times,” said Mike Cacheiro, vice president for Protected Communications at Lockheed Martin Space. “In the weeks ahead, AEHF-5 will move towards its operational orbit, deploy all of its solar arrays and antennas, and turn on its powerful communications payload for a rigorous testing phase prior to hand over to the Air Force.”

AEHF-5, with its advanced Extended Data Rate (XDR) waveform technology, adds to the constellation’s high-bandwidth network. One AEHF satellite provides greater total capacity than the entire legacy five-satellite Milstar communications constellation. “Individual data rates increase five-fold compared to Milstar, permitting transmission of tactical military communications, such as real-time video, battlefield maps and targeting data,” said Cacheiro. “AEHF affords national leaders anti-jam, always-on connectivity during all levels of conflict and enables both strategic and tactical users to communicate globally across a high-speed network that delivers protected communications in any environment.”

Lockheed Martin designed, processed and manufactured all five on-orbit AEHF satellites at its advanced satellite manufacturing facility in Sunnyvale, California. The next AEHF satellite, AEHF-6, was in full production in Silicon Valley and was expected to launch in 2020.

A United Launch Alliance (ULA) Atlas V rocket carrying the sixth Advanced Extremely High Frequency (AEHF) communications satellite for the U.S. Space Force’s Space and Missile Systems Center lifted off from Space Launch Complex-41 on March 26 at 4:18 p.m. EDT. This marks the 83rd successful launch of an Atlas V rocket, 138th launch for ULA and first mission for the U.S. Space Force.

The AEHF team includes the U.S. Air Force Military Satellite Communications Systems Directorate at the Space and Missile Systems Center, Los Angeles Air Force Base, Calif. Lockheed Martin Space, Sunnyvale, Calif., is the AEHF prime contractor, space and ground segments provider as well as system integrator, with Northrop Grumman Aerospace Systems, Redondo Beach, Calif., as the payload provider.


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