• A Delta IV rocket carrying the WGS-9 satellite lifts off from Cape Canaveral Air Force Station in Florida. International partners receive proportional access to bandwidth based on their financial contribution to the satellite in what could be a harbinger of future tactical military satellite communications (MILSATCOM) programs.
     A Delta IV rocket carrying the WGS-9 satellite lifts off from Cape Canaveral Air Force Station in Florida. International partners receive proportional access to bandwidth based on their financial contribution to the satellite in what could be a harbinger of future tactical military satellite communications (MILSATCOM) programs.
  • The Advanced Extremely High Frequency (AEHF) satellite, part of a constellation of six orbiters, is replacing the vaunted Milstar system. As advanced as these new satellites are, the U.S. Air Force already is looking toward the next generation of tactical satellites.
     The Advanced Extremely High Frequency (AEHF) satellite, part of a constellation of six orbiters, is replacing the vaunted Milstar system. As advanced as these new satellites are, the U.S. Air Force already is looking toward the next generation of tactical satellites.

Satellite Communications Go Tactical

October 1, 2017
By Robert K. Ackerman
E-mail About the Author

New threats and requirements drive development of constellations even as new ones begin to operate.


U.S. military satellite communications is expanding to provide greater coverage of the tactical environment as part of its overall mission to serve the land, sea and air domains. Broadening tactical coverage requires new types of satellites with a larger variety of capabilities, and these spacecraft must be shielded against threats ranging from cyber attack to on-orbit interference.

This expansion also means speeding up the development-to-orbit time for complex military satellites so that capabilities can be brought to warfighters without delay. The Air Force Space Command is working to develop new acquisition models to shorten that time frame while looking at commercial communications satellite technologies and systems to complement their military counterparts.

Bob Tarleton, director of the command’s Military Satellite Communications (MILSATCOM) Systems Directorate within the Space and Missile Systems Center, sees a clear shift in MILSATCOM toward tactical connectivity. One reason for the shift is that the strategic need to communicate is not going to change very much, while tactical communications demands are growing rapidly. Consequently, the percentage of tactical MILSATCOM will increase relative to the overall MILSATCOM total, while the amount of strategic MILSATCOM will be largely unchanged, except for upgrades.

“As we get more [tactical] capability in orbit, there is more and more demand for its use,” Tarleton posits. Also, new and next-generation satellites will be more versatile, opening them up to tactical users more so than their predecessors.

He explains that the center provides both protected and wideband MILSATCOM for warfighters. Protected MILSATCOM comprises strategic and tactical links, but it is tactical MILSATCOM that is growing in importance and activity.

Wideband MILSATCOM is less protected but provides a large pipe for information when speed is of the essence. The Wideband Global SATCOM system, or WGS, is the lead constellation in the world of wideband MILSATCOM, but it is supplemented by older satellites in the Defense Satellite Communications System (DSCS), which the WGS is replacing. New WGS satellites are in orbit, with one more scheduled for launch next year. 

Three Advanced Extremely High Frequency (AEHF) satellites are in orbit, and three more are slated to launch over the next three years to replace the Milstar constellations. The Enhanced Polar System (EPS), which also will provide protected EHF SATCOM to support tactical operations, will achieve initial operational capability (IOC) next year. It will cover northern regions of the Earth, primarily for the Navy, which has traditionally lacked effective SATCOM connectivity there.

Even as these new constellations assume their places in orbit, the center is looking ahead at replacement satellite systems. “We have come a long way since when we first started working in AEHF or WGS,” Tarleton says.

Among the systems in the works are ground-based technologies. The Protected Tactical Enterprise Service (PTES) will be a hub-and-spoke system that reaches out to tactical warfighters and uses the WGS constellation. It will tap the Protected Tactical Waveform (PTW), which the government developed to provide secure communications in a frequency-agnostic format. It adds more secure communications, so warfighters are more likely to have necessary connectivity while being less likely to have their location identified.

This waveform also can be used over commercial systems, which provides greater flexibility as the center develops future SATCOM architectures, Tarleton explains. The waveform is being added to the WGS as well as the PTES, which is scheduled to attain IOC in 2023. Protected Tactical SATCOM will follow to provide full tactical connectivity as it replaces the WGS and the EPS. Tarleton explains that it will perform the key functions of both systems in geosynchronous and polar orbits.

These new tactical space assets will pick up much of the WGS capabilities, although the exact amount remains to be determined, Tarleton says. An ongoing Defense Department SATCOM analysis of alternatives (AOA) will help establish the future architecture and its requirements. The Space Command is participating heavily in this analysis, which will include a look at a next-generation wideband system as well as protected tactical requirements. Another issue includes the balance between industry and government-purpose systems.

The Space Command’s Space Enterprise Vision, unveiled last year, links all aspects of space assets—acquisition, support, capabilities, training, resilience and security, as well as their involvement with the warfighting domain. The MILSATCOM Systems Directorate has several major defense acquisition programs (MDAPs), along with smaller programs and federally funded research and development efforts.

Even with the increased need for security in recent years, capabilities take top priority for MILSATCOM development. “We are continuing to evolve, as best we can, the capabilities of these current programs of record,” Tarleton offers. “Even after you get a satellite in orbit, there are some things you can do via software updates or ground infrastructure changes, so we are continuing to do that with both our AEHF and our WGS systems to make them more resilient.”

These efforts include antijam capability, along with other ways to defend satellites or to avoid space conflict. Wideband communications are known for high throughput without much protection. An antijam capability for the WGS is in development, and it may be fielded in a couple of years, Tarleton reports. “This antijam capability we’re putting on WGS moves that level of protection up a notch,” he says. “And, if you get PTW over that, you go up another notch.”

Space is not as benign an environment as it was just a few years ago, he points out. “We have to be able to defend our assets, particularly when we’re putting up a satellite that costs a billion dollars—you’d like it to keep operating for awhile,” he offers.

Cybersecurity has become part of the normal system-engineering process, Tarleton observes. It is introduced in the initial overall requirements for all hardware and software related to MILSATCOM, and it is being added wherever possible. “I feel good about MILSATCOM systems [cybersecurity], but there is always the next threat and adversary that is coming along—and we want to be ahead of them,” he declares.

It is crucial, especially in the end-to-end system, Tarleton continues. The AEHF, which was first launched in 2010, is being built to requirements now 17 years old. Clearly, changes have been made since then, and parts have become obsolete. Satellites for the constellation are still under construction, and AEHF-6, when launched in the future, will feature a new hardware-based resiliency. The Air Force continues to strive to improve both hardware and software, which Tarleton says is the biggest challenge. This involves the satellite; the ground infrastructure is another factor.

“It doesn’t do any good to have the best cybersecurity on a satellite if the ground infrastructure, and the whole network, isn’t also secure,” he offers.

Red teams have assessed the AEHF, and the Air Force is working toward the new risk management framework, which is the new way of managing cyber put forth by the Defense Department. The fact that the AEHF constellation is part of a closed network helps its security, Tarleton says.

Other approaches could find their way into orbit. Small satellites, or smallsats, are under consideration as the Space Enterprise Vision is implemented, but how they will be used along with MILSATCOM assets remains to be determined. Tarleton offers that smallsats have been launched as demonstrations for specific frequency ranges, but they have no role in existing systems.

The commercial sector offers promise with its high-capacity satellites, and the Space and Missile Systems Center also wants to take advantage of these advances, he says. Tarleton sees MILSATCOM exploiting these commercial satellites by incorporating wideband and protected tactical requirements.

“As we move forward into the next generation of systems and the architectures that we are considering … I expect commercial industry to be a big part of that as it has developed high-throughput satellites and has capabilities we would like to take advantage of,” he states.

For example, the Air Force’s Pathfinder program seeks to exploit commercial satellites by buying bandwidth or a transponder aboard an orbiter instead of leasing it. Pathfinder 2, which is scheduled to release a request for proposals by the end of this year, aims to tailor a transponder purchase by including MILSATCOM protection features before a satellite is launched. Air Force requirements embedded in the spacecraft during development could carry over to other commercial satellite constellations as a matter of course, enabling the satellites to serve military roles. Tarleton points out that it will take at least three years before a Pathfinder 2 satellite reaches orbit, but its success will prove the concept of combining commercial capability with MILSATCOM needs.

Pathfinder 2 is building a new business case for MILSATCOM as well, he continues. In addition to offering technical requirements, the military customer is exploring how to exchange equivalent bandwidth for access to an entire commercial satellite constellation. This will entail new contracting vehicles and other regulatory changes, and the Air Force is learning a lot about new ways on the business side, he says.

Pathfinder 3, which would be concurrent with Pathfinder 2, would feature a flexible modem interface allowing users to move from one system to another. A ground terminal modem would be built to permit this movement with enabled satellites, giving forces their choice of systems. It also could sow confusion among adversaries. This effort is being led by the Undersecretary of Defense for Acquisition, Technology and Logistics and the principal deputy space adviser, with the Air Force supporting it. Tarleton notes that his department’s advanced concepts division, which continually examines new technologies for use in MILSATCOM, is driving the Pathfinder program.

Moving new technologies into MILSATCOM entails many challenges. Upgrading ground systems is less difficult than altering on-orbit assets, although the ground upgrades must be compatible with the orbiting technology. Tarleton notes that upgrading ground systems is much less expensive and quicker than replacing the terminals, which can take years.

“We’re never going to move as fast as we want, and we want to get inside the time frame of our adversaries, who are figuring how they might attack our systems,” Tarleton says. “If that requires changes, we certainly want to be able to implement those changes ahead of when something really bad might be done to our systems. Often, it’s not just the technology—it’s how quickly we can get on contract.”

The Air Force’s MILSATCOM work is not limited to U.S. entities. The WGS already features six international partners. Australia actually paid for the WGS-6 satellite, while the United States paid for the launch, Tarleton says. WGS-9, launched in March, is the product of work by the United States, Canada, Denmark, Luxembourg, the Netherlands and New Zealand. Each nation is granted a percentage of the constellation’s bandwidth usage based on agreements among them, Tarleton explains. The Czech Republic also has expressed interest in joining WGS, he adds.

The directorate Tarleton oversees includes another division that focuses on aspects of international cooperation such as memoranda of understanding. The AEHF program has Canada, the Netherlands and the United Kingdom as international partners, and Australia also wants to join, Tarleton reports.

The AOA that the Space Command and the Defense Department are working on also includes international participation. As many as 16 nations were invited to take part, Tarleton says, and the center hopes to be able to use their ideas and technologies.

One international discussion brought to light a firm known as Space Norway, a Norwegian government-owned, privately held company. It is charged with launching a satellite by the end of 2022, and the Air Force offered to place a gap-filler satellite payload that falls between the EPS and the future protected tactical MILSATCOM system. Tarleton relates that the center has received the necessary approvals, but it must move quickly to meet its deadline. Among the tasks remaining are payload definition, contract placement and delivery by 2021. Achieving this will require streamlining acquisition documents and the approval process, he states.

The Space and Missile Systems Center has strong support for this effort from the Air Force Chief of Staff and the Secretary of the Air Force organizations, he continues. The U.S. government could save as much as $900 million on satellite bus, launch and integration costs if this succeeds.

“If we can’t go fast on this one, we’re not going to be able to go fast on any [other] space acquisition programs. We have all the stars aligned,” Tarleton says.

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