For decades, the Pentagon has wrestled with replacing large, monolithic satellites with more agile constellations of smaller spacecraft, a concept known as satellite disaggregation. Proponents have argued that distributed systems are more resilient against attack and allow more frequent technology upgrades.

This vision is gaining momentum, driven by the work of the Space Development Agency (SDA) — an organization under the U.S. Space Force that is developing a missile-tracking network in low Earth orbit using hundreds of relatively small satellites. By contrast, today’s missile detection architecture relies primarily on a small number of large satellites parked in geosynchronous orbits 22,000 miles above the Earth.

The Space Force is now looking to emulate aspects of SDA’s proliferated acquisition strategy, laying out plans to augment or replace the Defense Department’s backbone systems like protected communications, weather monitoring, and even GPS with clusters of smaller vehicles. Lt. Gen. Philip Garrant, head of the Space Systems Command that oversees Space Force acquisitions, observed that the procurement approach embraced by SDA is reverberating across the service.

“SDA has fundamentally changed acquisition,” Garrant said May 21 at a Mitchell Institute for Aerospace Studies event. “They have leveraged the commercial sector, they’ve leveraged relationships with the warfighter. So we’ve learned a lot of lessons from them.”

The Pentagon’s large, bespoke satellite programs are not completely going away. But disaggregation is increasingly taking hold across the U.S. military’s space architecture, said Cordell DeLaPena, program executive officer for military communications, positioning, navigation, and timing at the Space Force’s Space Systems Command.

This push for change, he said, is being fueled by lower launch costs, more capable small satellites, and other advances spearheaded by the private sector.


“Milsatcom is the first phase of our disaggregation,” said DeLaPena. “We’re going to provide resilient communications for warfighters.”

The Space Force plans to acquire three distributed satellite networks in the coming years as future replacements for the AEHF system, or the Advanced Extremely High Frequency constellation, which provides secure military communications for both strategic and tactical users.

DeLaPena told reporters recently that commercial space technology is creating opportunities to diversify the architecture. The Space Force is trying to deliver capabilities faster through more rapid acquisition cycles and technology refresh rates, and smaller satellites allow DoD to be more responsive to emerging threats and not be locked into the same capabilities for 10-15 years.

Today’s AEHF architecture consists of six large satellites that carry multiple payloads to support a range of functions like nuclear command and control, airborne communications for the presidential air fleet, and tactical communications for ground forces.

For strategic communications supporting senior leadership, a tracking and relay satellite constellation called Evolved Strategic Satcom is being developed. It will take over AEHF’s strategic roles, such as providing the U.S. president with assured connectivity during nuclear operations.

Tactical battlefield communications, meanwhile, will shift to a new proliferated architecture of two constellations in geostationary orbit known as Protected Tactical Satcom (PTS). The PTS-R will focus on resilience, providing anti-jam protection optimized for regional theater coverage in high-threat environments. Another set of lower-cost satellites, PTS-G, will provide global coverage for lower-risk operations.

PTS-R satellites will operate in the military Ka-band, and PTS Global will operate in the X-band and Ka-band.


The Pentagon’s bedrock positioning, navigation and timing constellation, the Global Positioning System, may get the small-satellite treatment. DeLaPena said his office will study whether payloads currently on GPS satellites can be hosted on smaller “GPS Light” companion spacecraft.

GPS spacecraft today carry a complex suite of tightly integrated payloads to support a range of positioning, timing, nuclear detection and other missions. That creates opportunities for disaggregation, said DeLaPena.

Among the payloads hosted on GPS satellites are sensors designed for search and rescue, and to detect nuclear detonations as part of the U.S. nuclear detection system. Putting certain payloads onto separate platforms could enhance resiliency while focusing the GPS constellation on its critical positioning, navigation and timing roles, he said.

The Space Systems Command has asked companies to submit concepts for a smaller, lighter version of GPS that would operate in medium Earth orbit alongside the traditional spacecraft.

“I’m very interested in the commercial market for GPS satellites,” said DeLaPena. “I think it’s going to be a game changer,” he added. Using commercial satellite buses and payloads, it would be possible to disaggregate GPS into smaller and cheaper platforms.

“We can start making GPS satellites a lot lighter and at a much-reduced cost,” he said.


For weather monitoring, the Space Force is looking to deploy a network of small- and medium-size environmental data satellites to complement weather services provided by civilian agencies.

A legacy system transitioning to a distributed architecture is the Defense Meteorological Satellite Program (DMSP).

The aging DMSP constellation, which provides strategic cloud characterization data to U.S. military forces, is down to just two operational satellites, which are expected to burn through their remaining fuel soon.

Rather than try to build a DMSP replacement, the Space Force is pivoting to a disaggregated architecture composed of separate satellite networks focused on different environmental sensing roles.

Frank Calvelli, Assistant Secretary of the Air Force for Space Acquisition, said May 21 at a hearing of the Senate Armed Services Committee’s strategic forces subcommittee that the idea is to take advantage of commercial and partner capabilities while also fielding some purpose-built constellations.

One new constellation will handle infrared and visible imaging for cloud monitoring — a role previously filled by DMSP’s primary payloads. A separate pair of satellites is planned to provide the microwave-sounding and atmospheric moisture-profiling data collected by DMSP’s secondary sensors.

These dedicated military platforms will supplement weather data from sources like the National Oceanic and Atmospheric Administration and the European Eumetsat program.

The Space Force recently launched the first prototype spacecraft in this new disaggregated weather architecture — a small satellite called the Electro-Optical Infrared Weather System. Calvelli highlighted this launch in congressional testimony as the first phase of “a pivot to a more resilient disaggregated hybrid weather architecture to meet warfighter requirements.”


Another area being reshaped by the military’s space disaggregation push is space domain awareness, or the monitoring of objects in valuable orbits
around Earth.

Today, that mission relies heavily on the Geosynchronous Space Situational Awareness Program (GSSAP), which consists of large satellites that provide specialized monitoring of resident space objects in the geosynchronous belt.

The Space Systems Command issued an RFI (request for industry information) in March on a potential constellation of lower-cost “free flyer” satellites with electro-optical sensors to conduct rendezvous and proximity operations.

The RFI indicates the Space Force wants to shift away from highly specialized, big-ticket satellites for space domain awareness in favor of a continually refreshed constellation of commoditized small satellites with interchangeable payloads. “The goal is to establish a replenishable constellation,” the command said in the solicitation.


Industry executive Charles Beames calls the military’s renewed push for satellite disaggregation a long-overdue correction.

For decades, the DoD piled on missions onto massive satellites, said Beames, who heads an industry group known as the SmallSat Alliance and more than a decade ago served as principal director for space and intelligence in the Office of the Secretary of Defense.

At the time, very large monolithic satellites were favored because of the high cost of building and launching, so the Pentagon tried to pack as much capability on a spacecraft as possible. The result, he said, were multi-billion dollar programs that took decades to develop. These satellites also became attractive targets for adversaries who realized they could weaken America’s military might by disabling just one system.

Beames noted that now retired Gen. John Hyten—who then led the Air Force Space Command—and former space policy official Doug Loverro in the early to mid-2010s were advocating disaggregating large satellites.

“Their views were prescient,” said Beames. But in those days before SpaceX entered the national security launch market, he said, the cost of putting satellites in space was high, and there were very few small satellite builders. “The major primes that built satellites were completely against the idea and lobbied heavily against it.”

SDA’s proliferated constellation program proves that the disaggregation strategy can shake up the traditional space industrial base, said Beames. The companies that produced custom-built spacecraft under cost-plus contracts for decades now have to compete in the new business environment of fixed-price contracts and lower-cost satellites.

Calvelli, the Space Force’s top procurement official, has directed acquisition program offices to leverage the commercial small-satellite industry’s innovation and reduce their reliance on a few large primes.

“We’ve proven now that we can build small satellites quickly,” Calvelli said at the Senate Armed Services hearing. “Proliferation is absolutely one of the key elements of a resiliency strategy that supports mission assurance.”

“We can move smartly to a more defensible architecture that is not dependent on individual exquisite systems,” Calvelli added. “We’re showing we have the ability to go fast by tapping into the commercial space industry.”

This article first appeared in the June 2024 issue of SpaceNews Magazine.

Sandra Erwin writes about military space programs, policy, technology and the industry that supports this sector. She has covered the military, the Pentagon, Congress and the defense industry for nearly two decades as editor of NDIA’s National Defense...