"Our Nuclear Shield Was Killed For Political, Not Technological Reasons"– Reagan's SDI Director Ambassador Henry Cooper on Reviving the Brilliant Pebbles Program & Why America's Golden Dome Defense Can Finally Be Built

In the winter of 1957, a junior engineering student at Clemson University named Henry Cooper heard news that would forever alter the trajectory of his life: the Soviet Union had launched Sputnik, the world's first artificial satellite. The beeping metal sphere orbiting above American soil represented more than just a technological milestone—it was a stark warning that the United States had fallen behind.

"It caught us with our pants down," Ambassador Cooper recalls, his voice still carrying traces of indignation six decades later. "We were totally unprepared."

Today, America faces a far more perilous crossroads. Russia tests nuclear-powered cruise missiles designed to evade all defenses. China deploys hypersonic weapons that can maneuver unpredictably at over five times the speed of sound. North Korea arms multiple warhead missiles while Iran advances its nuclear and satellite programs. Our existing missile defenses—designed for a simpler threat landscape—cannot adequately protect the continental United States and many experts believe they are becoming increasingly obsolete as adversary capabilities advance.

President Trump’s "Golden Dome" initiative represents the most ambitious defense undertaking since Reagan's Strategic Defense Initiative (SDI)—and possibly America's last opportunity to deploy a comprehensive shield before adversary capabilities overwhelm our defenses entirely.

Cooper, now 88, sees in Golden Dome the resurrection of his "Brilliant Pebbles" concept – a constellation of small, autonomous interceptors in space that could engage missiles throughout their entire flight path. Though fully validated by Pentagon studies with many components successfully tested in the early 1990s, the program was eliminated by congressional opponents for political rather than technical reasons and completely dismantled when the Clinton administration took office. Three decades of technological advancement later, what once required a room-sized supercomputer now fits in a smartphone, and what cost billions to launch now costs millions. Cooper believes we now need a “do-over.”

"The technical question was never whether it would work," Cooper insists, leaning forward in his chair. "The question is whether we'll finally do the right thing now, before it's too late."

In this exclusive interview, one of the architects of America's most ambitious defense concept explains why the Golden Dome isn't just possible—it's absolutely necessary, and why after thirty years of political resistance, America might finally build the space shield that Reagan envisioned and its adversaries have always feared.

Before we dive into the Golden Dome initiative, could you share your personal journey in space-based defense? What first drew you to this field, and how did your path lead to becoming President Reagan's defense and space negotiator and eventually the director of the Strategic Defense Initiative?

Ambassador Cooper traces his interest in space defense to a transformative moment in American history. “My entry into addressing space issues began with the Soviet Union’s 1957 launch of Sputnik,” he recalls. “It caught us completely unprepared.” At the time, Cooper was a junior engineering student at Clemson University. The startling success of Sputnik ignited his fascination with space technology and defense, setting the stage for his lifelong commitment to national security.

Upon graduating, Cooper joined Bell Laboratories in New Jersey while pursuing his PhD at NYU. There, he contributed to one of America’s first landmark space achievements: Telstar, the pioneering communications satellite launched in 1962.

“My wife and I traveled to my BTL office to witness the very first television transmission through space—from a colossal 100-ton antenna near Paris to another near Rumford, Maine,” he says. “It’s hard to imagine today, with everything you can hold in the palm of your hand, but that was our first televised broadcast. The first image was the American flag with the Star-Spangled Banner in the background.”

That same period marked Cooper’s first encounter with electromagnetic pulse (EMP) effects—a topic that would become central to his career. In July 1962, the United States conducted the Starfish Prime nuclear test high above the South Pacific. The resulting EMP disrupted electronics nearly 900 miles away in Hawaii, revealing the devastating potential of even very high-altitude, distant nuclear detonations.

“That test introduced us to the modern era of nuclear weapons effects,” he explains. “We anticipated electromagnetic effects, but we were stunned by their intensity. That’s what sparked my enduring focus on EMP—critical vulnerability that still threatens us today, and one we’re still failing to address.”

Cooper underscores that these threats can arise from both man-made sources, such as nuclear detonations, and natural phenomena like major solar storms known as coronal mass ejections. The most significant of these on record—the 1859 Carrington Event—damaged and disrupted telegraph networks at the time. 

“If—or rather, when—a similar event occurs today, it would devastate our unprotected electric grid,” Cooper warns. “In 1859, we didn’t have phones, computers, or complex networks. But if that kind of solar storm struck now, it would destroy critical components of our grid—cutting off electricity nationwide. The consequences would be catastrophic: widespread starvation, disease, and societal collapse. Most Americans wouldn’t survive.”

Cooper’s military career began after graduating from Clemson, when he was commissioned into the U.S. Air Force. At the time, a surplus of mid-grade officers following the Korean War led to an educational delay, allowing him to pursue a Ph.D. in engineering from NYU. He was then assigned to the Air Force Weapons Laboratory at Kirtland AFB in New Mexico, where he developed deep expertise in protecting strategic systems—particularly ICBMs—from the full spectrum of nuclear effects, including electromagnetic pulse (EMP) generated by high-altitude nuclear detonations.

“That’s where I became deeply involved in strategic matters,” Cooper notes. “Our focus was on hardening critical strategic systems—primarily our ICBMs, and, to a lesser extent, our submarines, and, similarly, our bombers and aircraft. Most importantly, we focused on securing the key communication systems that allow our political and military leaders to maintain control over them.”

His technical acumen and leadership propelled him to Washington, D.C., where he became Deputy Assistant Secretary of the Air Force. “At the time, the Air Force bureaucracy was leaner,” he says. “I was effectively the third-ranking civilian, overseeing all USAF strategic and space systems, including some clandestine operations of the National Reconnaissance Office (NRO)—which we couldn’t even publicly acknowledge then.”

Cooper’s most defining role in shaping the politics of space-based defense came during the Reagan administration. “I was first brought into the State Department to lead the backstopping efforts for all of our strategic arms control negotiations with the Soviet Union,” he explains.

In 1984, however, the Soviets withdrew from all arms control talks in an attempt to influence political opinion—and upcoming elections—in the U.S., NATO, and allied nations. Their withdrawal was explicitly tied to opposition to the Strategic Defense Initiative (SDI), which had been both announced and effectively launched by President Reagan’s March 23, 1983 speech. Fortunately, Reagan and the leaders of key allied nations were all re-elected, reinforcing support for SDI.

When negotiations resumed in 1985, Cooper was appointed as Reagan’s Ambassador and Deputy Negotiator—and later Chief Negotiator—of the new Defense and Space Talks. “My primary mission was to protect Reagan’s SDI,” he affirmed. “Reagan was deeply committed to building strategic defenses to protect the American people. In my role, I worked to uphold that vision—resisting not only Soviet pressure, but also internal efforts within the U.S. government to concede to their demands.”

Moreover, he represented President Reagan’s perspective in his Summits with Soviet General Secretary Mikhail Gorbachev. Shown above is a photo from the 1987 Washington Summit, following all-night negotiations before they signed the INF Treaty that led to the elimination of thousands of nuclear weapons that threatened our NATO allies and potentially also our allies in the far east.

In these negotiations, Cooper reflected Reagan’s mindset (which he shared): “He was never comfortable with the doctrine of mutual assured destruction (also known as MAD). He questioned whether any American leader would truly retaliate if it meant annihilating the Russian people. He believed that national defense should include actual protection, not just deterrence.” 

This ideological pivot had reached its apex at the Reykjavik Summit in October 1986, where Reagan famously walked away from a potential arms deal with Gorbachev rather than accept limits on SDI, especially in space-based experimentation. In subsequent negotiations, the U.S. captured concessions Gorbachev had made in Reykjavik, leading to the first ever arms control agreements to achieve major reductions in nuclear weapons. Below is a photo and note from President Reagan to Ambassador Hank Cooper, as he completed his second term as President, emphasizing this achievement. Cooper's SDI efforts continue even today.

Following his efforts as Chief Defense and Space Negotiator in Geneva into the subsequent administration of President George H.W, Bush, Cooper became the third SDI Director. In an early meeting in Colorado Springs, he hosted British Prime Minister Margaret Thatcher at the SDI National Test Facility in 1991. She reviewed much of the SDI efforts and spoke to SDI’s assembled Principal Investigators and declared: “I firmly believe that the commitment to SDI eventually convinced the Soviet Union that military victory was impossible.”

Cooper affirms that SDI fundamentally reshaped the strategic landscape: “It achieved what the Soviets couldn’t—and they knew it. That gave us tremendous leverage in our negotiations and led to the first meaningful arms control treaties: INF and START, which together reduced nuclear arsenals by many thousands of nuclear weapons.”

When you led SDI in the early 1990s, space-based defense faced significant technological and cost barriers. What progress did SDI make then, and how have recent commercial innovations transformed what's possible for the Golden Dome initiative compared to the original SDI vision?

When George H.W. Bush assumed the presidency in 1989, the world stood on the brink of geopolitical transformation. The collapse of the Soviet Union was imminent, and with it came a strategic inflection point. “The question was, what do we do next in all of this, in a world that is no longer bipolar?” Ambassador Cooper reflects.

Amid this uncertainty, a groundbreaking concept emerged—Brilliant Pebbles. It originated at Lawrence Livermore National Laboratory, developed by a team that included Edward Teller and Lowell Wood. Bill Graham was Reagan’s chief science advisor and a longtime colleague of Cooper’s from their early days as USAF Lieutenants at the Air Force Weapons Laboratory in the 1960s. “Bill arranged to brief President Reagan on the concept,” Cooper explains. “Reagan liked the idea of Brilliant Pebbles, and that’s how it became a serious program.” In the following figure, Bill Graham is seated next to USAF Lt. Gen. Jim Abrahamson, the first director of the Strategic Defense Initiative.

As the Brilliant Pebbles program became public knowledge, it encountered fierce political opposition despite demonstrating clear technical advantages over other missile defense systems under SDI consideration. This resistance was spearheaded by leadership in both the Senate and House Armed Services Committees. When the Clinton administration formed in 1993, former House Armed Services Committee Chairman Les Aspin became Secretary of Defense and swiftly terminated the program. His administration instead prioritized arms control agreements and invested in less effective, more expensive ground-based defenses that complied with the 1972 Anti-Ballistic Missile (ABM) Treaty.

Cooper had anticipated this outcome, having already encountered resistance from key Senate and House leaders. In response, he launched two key initiatives that would prove important for future technological developments.

First, he established a space-based sensor program called Brilliant Eyes to support ground-based defense systems. Though technically redundant—since Brilliant Pebbles already incorporated advanced sensors capable of supporting multiple defense platforms—this strategic move ensured that vital space-based sensing capabilities would survive the political transition and continue benefiting ballistic missile defense systems, including those in service today.

Second, Cooper initiated a project that could both withstand political scrutiny and demonstrate the core technologies behind Brilliant Pebbles. The result was Clementine, a joint mission with NASA that repurposed the Pebbles sensor suite to map the entire surface of the Moon. After completing its primary objective, Clementine was programmed to swing past Earth, use its gravity for a slingshot maneuver into deep space, fly by and map an asteroid, and then continue on—“lost and gone forever,” as its nostalgic name suggests. The mission exceeded all expectations, so much so that a replica earned a permanent display at the Smithsonian. The team also validated its miniature rocket thrusters in a separate test flight known as Astrid (as shown on the right).

Together, the Brilliant Pebbles, Clementine, and Astrid missions demonstrated the viability of small, autonomous space systems for both defense and exploration purposes three decades ago, establishing a technological foundation that continues to influence space innovation today.

The program’s origins had followed an unconventional path. In 1988, Edward Teller visited Cooper in Geneva—where he was negotiating with the Soviets—to personally share the Brilliant Pebbles concept. He invited Cooper to Lawrence Livermore National Laboratory to view the research firsthand. Cooper was impressed and attempted to engage the Air Force’s space interceptor program managers, but they promoted institutional resistance.

“The Air Force bureaucracy flatly refused,” Cooper recalls. This pushback led him and others to advocate for an independent Brilliant Pebbles Task Force, reporting directly to the SDI Director. This decision—to bypass conventional Air Force channels—proved crucial to getting the program off the ground.

Brilliant Pebbles marked another revolutionary departure from earlier space-based interceptor systems. Instead of relying on massive, centralized "Battlestar Galactica" platforms carrying multiple interceptors, the new approach relied on swarms of small, lightweight, autonomous “brilliant” interceptors dispersed throughout space.

Cooper emphasized, “The small interceptors weighed just a few hundred pounds—mostly fuel. Each carried its own sensors, computer, and propulsion system; and monitored its location and relative situation re: potential targets and consequent launch decisions—and shared that information with neighbors throughout the constellation and the overall BP constellation.” This miniaturized, self-contained design—with distributed battle management—made the system significantly more economical and scalable than its predecessors.

Despite this technical promise, political opposition eventually hamstrung the program. “In my final year as SDI Director, I was forced to curtail the Brilliant Pebbles effort,” Cooper says, citing resistance from top legislators: Senator Sam Nunn, Chair of the Senate Armed Services Committee; Senator Carl Levin, his deputy; and Representative Les Aspin, Chair of the House Armed Services Committee (and later Clinton’s Secretary of Defense).

This opposition was deeply rooted in politics. President Reagan had been so enthusiastic about Brilliant Pebbles that he vetoed the 1989 National Defense Authorization Act when it attempted to slash funding for space-based interceptors. When Aspin took over the Pentagon under President Clinton in 1993, he made good on his promise to “take the stars out of Star Wars,” effectively dismantling the entire program. 

Yet, despite the political turbulence, Cooper and his team managed to space-qualify every critical element of the Brilliant Pebbles concept. “We validated all the key technologies,” he affirms. In anticipation of funding cuts, Cooper launched the Clementine mission—an ingenious workaround to prove the system’s capabilities in space. (See the earlier discussion and accompanying photo of Clementine and Astrid.)

“We formed a small team to pull off a space mission once it was clear SDI was going to be shut down,” he explains. The team, at the Naval Research Laboratory, was led by Pedro Rustan and consisted of just six or seven people. “We deliberately avoided having the Lawrence Livermore team lead the mission, knowing the political climate would likely doom the effort if they were front and center.”

Clementine launched in January 1994 and, as previously noted, proved to be a remarkable success. It became the first U.S. mission to the Moon in 25 years, mapping its entire surface using 13 spectral bands. “It took 8 million photos, and was the first to discover water (ice) in the lunar polar regions, and tested every sensor we would have flown in a Brilliant Pebbles constellation,” Cooper says. “We also tested the miniature thrusters designed for missile intercepts—validating every aspect of the 1992-era Brilliant Pebbles concept. This wasn’t theoretical—it was proven capability.”

The SDI DC-X program offered another powerful demonstration of lean, fast-track innovation—proving that a reusable rocket system could take off vertically, maneuver, land, and relaunch. It showcased the dramatic potential for improving responsiveness and reducing the cost of deploying and maintaining space-based defenses. “It took some time,” Cooper notes, “but today the commercial sector is fully embracing technologies that SDI demonstrated over 30 years ago.” For example, consider the Iridium system.

The Brilliant Pebbles legacy also has been extended to many other private sector programs as well. It directly influenced the team behind the original Iridium satellite constellation. “The Iridium project initially included technologists from the Brilliant Pebbles world,” Cooper notes. “They, a couple of decades ago, showed that the BP concept was operationally viable and executable by a small, dedicated team.” Today, the SpaceX Starlink and Amazon Kuiper teams have taken the technology to a whole new level of investment and commercial utility as they extend the internet to space.

Iridium drew inspiration from earlier concepts, including Brilliant Pebbles. Its reliability and operational success helped validate the feasibility of distributed satellite systems for space-based defense, managed by just a handful of experts. Between May 1997 and November 1998, the Iridium team successfully launched 95 satellites, peaking at a rate of four per week. Their reliability was extraordinary: only two failed in the first several years and the system still supports key operations today. This unmatched success validated the viability of Brilliant Pebbles’ decentralized, small-satellite approach.

As for the future, Cooper is unequivocal: “The technical question isn’t whether it would have worked. The question is whether we’ll do the right thing now.”

Given today's commercial space capabilities, what deployment and maintenance strategies would make the most sense for Golden Dome - particularly the on-demand reusable launch options you've highlighted?

Ambassador Cooper is unequivocal: The primary obstacle to effective space-based defense is not technological—it is bureaucratic. “That’s nothing new,” he says. “It was a challenge in our day, too. One of the biggest opponents we had in executing the SDI program was the military—specifically, the Air Force—because they believed they were in charge of space.”

This institutional resistance has long-standing roots. During the SDI era, Air Force Lieutenant Generals James Abrahamson and George Monahan, both SDI directors, encountered significant pushback from within their own service. When General Monahan discovered that the Air Force Space and Missile Systems Organization, now known as the Space Systems Command (SSC), was refusing to seriously consider the Brilliant Pebbles concept, he took bold action.

Cooper himself secured a crucial organizational advantage when taking leadership of SDI. "When Defense Secretary Cheney, with President Bush's endorsement, asked me to become SDI Director, I agreed on one condition: That I work directly for him, directly reporting to him. And he agreed," Cooper explains. "This meant that when there were bureaucratic obstacles—and there were some—I could bring issues directly to him without navigating a bureaucratic maze. I only had to exercise that privilege a couple of times, and after the bureaucracy understood that this channel existed, most obstacles disappeared." Cooper emphasizes this lesson for current initiatives: "It's vital that the SecDef and President see eye-to-eye on executing the President's program. If the Golden Dome is to succeed, I strongly urge that its director be granted that same privilege."

"George fired them outright," Cooper recounts. "The bureaucracy was the problem then, and it's the problem today. Bureaucracies are designed to slow things down—and that's exactly what they do. What's needed now is the same kind of direct, empowered approach we took in my time."

Cooper expresses concern that the Golden Dome initiative may be falling into the same trap: relying on traditional, slow-moving organizations. "What worries me about Golden Dome—and this talk of a 'Manhattan Project'—is that it could lead to building yet another bureaucracy," he cautions. "What they really need is someone competent, empowered to lead a small, focused team that can move fast and deliver results."

Cooper emphasizes that modern technology has greatly simplified the problem and should be leveraged. “Commercial reusable launch systems have reduced launch costs by an order-of-magnitude in the last decade and emerging competition may drive those costs down by another. Given commercial constellations of “smallsats” and “cubesats”, orbital transfer vehicles maintaining constellations, and routine military demonstrations of high speed intercepts, you have the technological basis for low-cost space-based defenses, defenses which could actually reduce net defense spending in the future.”

This strategy mirrors what made Brilliant Pebbles successful in its early days: bypassing entrenched acquisition pathways in favor of lean, agile teams using commercial, off-the-shelf technology whenever possible.

Cooper sees an obvious example in Elon Musk. “I don’t think you can get Elon to focus on a single thing,” he admits, “but you could make him responsible for assuring that the Golden Dome begins by including current, off-the-shelf technology with only minor modifications.”

Indeed, SpaceX has demonstrated nearly all the required capabilities: rapid design and deployment cycles, drastically reduced launch costs, scalable satellite mass production (Starlink), and autonomous constellation management. While Musk’s passion has centered on Mars rather than military defense, Cooper believes his model offers a compelling template for the Golden Dome.

He’s also optimistic that the current political environment might finally support the kind of nimble execution that space-based defense demands. “This is the first time you’re seeing an administration made up of successful businesspeople,” Cooper observes. “Take JD Vance, for instance. He’s an entrepreneur. Elon Musk is an entrepreneur. There are dozens of people in this circle with serious business credentials.”

“This is kind of unprecedented,” he continues. “And given their backgrounds and their intent to cut bureaucracy—we’ve already seen them begin removing personnel that were supposedly ‘essential’—it might just be the perfect storm.”

Cooper then lays out a compelling technical and economic case for why space-based interceptors are vastly superior to their ground- or sea-based counterparts.

“If you want to expand current missile defenses,” he explains, “you’d need to build a new ship, base, or facility every few hundred miles to gain global coverage. You’d have to ring the entire United States—and then do the same for all our allies. That means hundreds, if not thousands, of essentially point-defense sites scattered across the globe.”

By contrast, space offers a fundamentally more efficient solution. “Say I have a 100- to 200-pound interceptor. No matter what, I’ve got to get that into space. If I start orbiting in space, I already have a Mach 25 velocity advantage. If I’m on the ground, I need a huge, fast booster to catch up. That means using a 10,000- to 30,000-pound rocket just to deploy a few small interceptors—and aerospace hardware is priced by the pound.” He adds, “Thanks to today’s commercial, reusable, low-cost launch systems, we can eliminate the need for those expensive, one-off boosters entirely.”

“That’s part of where this whole ‘Manhattan Project’ complexity is coming from,” he explains. “But if you're willing to take the initial step to employ space-based defenses, everything becomes simpler and cheaper.”

The physics and geometry of space-based defense reinforce this logic. Ground- and air-launched interceptors must be stationed near threat zones to be effective, requiring massive infrastructure across continents and oceans. But interceptors in low Earth orbit, moving at 7.8 km/s (Mach 25), can cover the entire globe with far fewer assets. This capability is especially critical against emerging threats like hypersonic missiles or launches from unexpected locations.

While some defense officials have suggested Golden Dome requires a Manhattan Project-scale effort, you've argued it could be much more affordable. What specific Brilliant Pebbles studies and hardware demonstrations at SDI led you to this conclusion?

Ambassador Cooper addresses cost concerns surrounding space-based defense by drawing a stark comparison between past SDI era and present computing power. “At the time we were doing Brilliant Pebbles, I had a hand calculator,” he recalls. “I used to go around saying, ‘You know, this is the size of the computer on a Brilliant Pebble.’ Today, that comparison is even more striking—my phone has more computing power than the room-sized Cray CDC 6600, which once filled a gymnasium alongside walls of tape recorders. The comparison is staggering—it is generations more capable in the artificial intelligence world we live in today than it was then.”

Today, smartphones exceed that old level of Cray power by orders of magnitude. Combined with advances in artificial intelligence, autonomy, and sensor technology, tasks such as target discrimination, tracking, and battle management are now significantly easier and more reliable than they were decades ago.

Cooper has addressed the affordability of space-based defense systems in formal publications. One example is a September 19, 2018 article in The Washington Times, co-authored with retired Air Force Colonel Rowland “Rhip” Worrell, former commander of the SDI Brilliant Pebbles Task Force. The piece directly challenged the common assumption that space-based defenses are inherently cost-prohibitive. They defended a cost estimate made by then–Under Secretary of Defense for Research and Engineering Michael Griffin, who had previously served as SDI Director of Technology. He estimated that a constellation of 1,000 space-based interceptors could be built and deployed for under $20 billion in 2018 dollars.

This estimate was strikingly consistent with an earlier analysis by the Pentagon’s Cost Analysis Improvement Group (CAIG) (now known as the Cost Assessment and Program Evaluation (CAPE)), which in 1989 projected that deploying 1,000 Brilliant Pebbles—including full research and development, launch, deployment, and 20 years of operation—would cost around $10 billion in 1988 dollars. Cooper notes that this financial continuity across decades, despite inflation and technological advancement, underscores just how cost-effective such systems can be with the right approach.

Central to Cooper’s philosophy is the idea of small, agile, empowered teams of young innovators. “There are bright young experts—people who have engineering and other supporting degrees, perhaps even PhDs—that can do that job,” he says. “You need a shepherd over them that understands and will protect them, because there is no perfect world, and they will make mistakes. We made them. You’ve got to have bosses that are willing to say, ‘Well, let’s pick up the pieces and go again.’”

This innovation culture traces back to General Bennie Schriever, who built America’s intercontinental ballistic missile (ICBM) force in the 1950s by assembling government and industry teams of young, high-performing engineers. Schriever shielded them from bureaucratic interference, then funded and empowered them to move fast—an approach Cooper replicated during SDI, especially in the Brilliant Pebbles program and later the Clementine mission. Clementine, developed in under two years on a tight budget, space-qualified several systems originally designed for missile interception.

Looking at today's capabilities, Cooper points to Elon Musk’s Starlink constellation as evidence that the technologies required for space-based defense are not only available, but also proven at scale. “Elon’s already put up tens of thousands of these little satellites,” Cooper notes. “Those aren’t CubeSats—they’re multi-thousand-pound satellites. They cost less than a million dollars each, and they contain all kinds of small components suitable for future space defenses.”

He elaborates on the relevance to defense: “You can also use that whole command and control data link through Starlink to control everything. That’s almost off-the-shelf technology—it’s 90% of the way there.”

Cooper’s argument is clear: the combination of mature commercial hardware, modern autonomy, and streamlined team structures offers a direct, affordable path to reactivating space-based missile defense—without the need for a bloated “Manhattan Project” bureaucracy. It’s not a matter of whether the technology works—it’s about empowering the right people to execute with speed, agility, and focus.

You've noted that all classes of intercept - boost phase, mid-course, and terminal phase - are possible with space-based systems, including against hypersonic threats. Please elaborate on the constellation structure needed for continuous coverage?

Ambassador Cooper draws on Strategic Defense Initiative (SDI)-era studies to outline a practical and effective space-based constellation. “For the space defense part that we would do immediately—based on what we analyzed with the Pebbles—a few thousand interceptors makes sense,” he explains. “They should be relatively lightweight, with fuel being the heaviest component on the vehicle.”

This constellation was originally sized to ensure near-total coverage against one of the most serious Cold War threats: a Soviet submarine-launched missile barrage from just off the U.S. coastline. At the time, that scenario posed such a significant danger that strategic bombers were kept on constant “strip alert,” engines running on the tarmac, ready to take off at a moment’s notice to escape the initial strike and carry out a retaliatory response.

During the SDI program, the constellation design initially centered around deploying approximately 1,000 Brilliant Pebbles in low Earth orbit (LEO). Each interceptor was designed to function autonomously, equipped with its own sensors, onboard computer, and propulsion system. This distributed architecture ensured resilience: there was no single point of failure, making the system robust against both mechanical issues and enemy attacks. (Larger constellations were also considered and could have followed the initial deployment of 1,000 Brilliant Pebbles once their operational capability was demonstrated.)

Cooper emphasizes that the concept of space-based defense has deep, well-established roots. “The original DARPA studies from 50–60 years ago concluded that space was the right answer for effective missile defense, but the technology wasn’t available to do it then,” he says. “So it’s not a new idea that you should be doing things in space to take advantage of the inherent benefits of being in Earth orbit.”

These early insights came from Project Defender, conducted by the Advanced Research Projects Agency (ARPA)—now DARPA—in the 1960s. These studies identified space as the most effective domain for intercepting ballistic missiles, laying the theoretical foundation that would inspire Reagan’s SDI. While the technology wasn’t mature enough in the 1960s, the advancements of the 1980s—and the exponential progress since—have brought that vision within reach.

Cooper explains the unique advantages of space-based systems using insights from SDI-era technical briefings. “Just look at all the shoot opportunities you get—even on relatively short-range missiles,” he says. “You can’t intercept ballistic missiles during boost phase from ground-based interceptors invariably located far away, but from space, you can intercept rockets while they’re still burning in the boost phase of flight. In fact you get multiple intercept opportunities as the missile ascends.”

One of the critical strategic benefits of space-based systems is their ability to engage threats across all phases of flight—boost, mid-course, and terminal. Most importantly, they can target missiles during the boost phase, when rockets are still accelerating and have not yet deployed decoys or countermeasures. This capability is especially vital against modern threats such as MIRVs (multiple independently targetable reentry vehicles), which China has already demonstrated with success.

“You can shoot them even on their way down,” Cooper adds. “As they’re reentering the atmosphere—which is where the current generation of hypersonic threats operate—they’re in the upper atmosphere and can maneuver, which makes them difficult to hit. But with an aero-shape you can hit them from space, on their way down.”

Hypersonic weapons represent one of today’s most urgent strategic challenges. Flying at lower altitudes than traditional ballistic missiles and capable of high-speed maneuvers, they are extremely difficult to target with current ground-based defenses. In March 2018, then–Under Secretary of Defense for Research and Engineering Michael Griffin made clear the urgency of this threat, stating: “I didn’t take this job so that we could regain parity with our adversaries. I want to see their hand and raise them one. I want to make them worry about catching up with us again.”

Cooper cites actual Brilliant Pebbles test results that validated these capabilities. “In the tests we conducted before the Clinton administration came in and killed the program, we were working with first-generation Pebbles,” he recalls. “In one of those tests, the Pebble was chasing the target and the target went amok—it wasn’t the Pebble’s fault—and the BP continued to track it downward, all the way to under 100,000 feet. That’s the region where hypersonic vehicles operate and maneuver. So even back then, the original BP conceptual system promised the potential to intercept those kinds of hypersonic threats.”

Looking ahead, Cooper envisions a dual-track strategy that balances immediate deployment with long-term innovation. “I would put my basic research dollars into directed energy,” he says, “and I would use my development funds to make the best of what modern technology can provide for kinetic interceptors. Then take whatever improvements beyond that make sense.”

Importantly, Cooper is not suggesting a return to the original Brilliant Pebbles blueprint with a massive new R&D program. “It’s not to say that everything may be in hand—because I don’t know that—but I do know enough about how the technology works to believe that it’s all out there. It’s a matter of assembling it.”

His approach aligns with the classic “crawl, walk, run” philosophy:

• Near term: Deploy updated kinetic interceptors based on proven Brilliant Pebbles designs using today’s off-the-shelf military and commercial technology.
• Long term: Invest strategically in directed energy weapons such as lasers and neutral particle beams, which could revolutionize boost-phase defense by eliminating or reducing the need for interceptors altogether.

In Cooper’s view, the choice is not whether we have the means—but whether we have the vision and agility to assemble and deploy them effectively.

The Path Forward: Golden Dome Initiative

Major geopolitical developments have consistently driven shifts in U.S. defense and space policy. The 1957 launch of Sputnik led directly to the creation of NASA and ARPA (now DARPA). The Soviet deployment of multiple-warhead missiles in the 1960s reignited interest in mobile-based ICBMs and ballistic missile defenses strategic defense to enhance the survivability of our Minuteman ICBMs.  

Indeed, a 1988 Defense Board Summer Study (during Cooper’s watch as USAF Deputy Assistant Secretary for Strategic and Space Systems) considered these issues and found that such a missile defense system was the most cost-effective alternative way to protect our silo-based ICBMs. But such a defense was prohibited by the 1972 ABM Treaty. And mobile ICBM basing also became unacceptable. So, we ended up “stuffing” the very large “MX” ICBMs in upgraded (but still vulnerable) silos.  And they were abandoned in concert with the Strategic Arms Reduction Talks (START) with the Soviet Union. 

More recently, China’s 2007 anti-satellite test, North Korea’s nuclear and missile advancements, and China and Russia’s development and proliferation of hypersonic weapons have all underscored the need for advanced, multi-domain defensive capabilities.

And we should not forget that Iran participated in North Korea’s underground nuclear tests that validated its nuclear weapons, so we should not be surprised if it turns out that they already have a rudimentary nuclear capability.  

Cooper recalls how innovation has often emerged in spite of bureaucracy. “The early Navy space launch efforts weren’t successful. That was Vanguard. Their effort failed because they tried to do it the traditional way,” he explains. “The Air Force took a different path. A young Brigadier General, Bernard Schriever, was allowed to lead outside the existing USAF R&D establishment. He recruited as many young PhDs as he could find—along with other top talent—and brought in a new civilian cadre to provide Scientific, Engineering, and Technical Direction (SETD). That team went on to develop the nation’s ICBM program in record time.” Admiral Hyman Rickover adopted a similar streamlined model to build the Navy’s first submarine-launched ballistic missile (SLBM) capability—also in record time.

One of the most transformative episodes in modern missile defense occurred during the 1991 Gulf War. “We had three Patriots—never tested,” Cooper recounts. “Thanks to a young lieutenant colonel in Huntsville, and the willingness of the leadership there, we turned on the production lines of that untested Patriot. Every Patriot used in the Gulf War—280 to 300 of them—was an untested missile.”

But the most significant breakthrough, particularly in Israel, wasn’t technical—it was psychological and political. “People went back to work,” Cooper recalls. “Before then, Scud attacks kept them hunkered down in shelters and basements. Even limited missile defense changed that. It shifted the political landscape.”

That shift aligned with visits to Israel by influential members of Congress, including Senator Sam Nunn (D-GA), then chairman of the Senate Armed Services Committee. “He and others in that congressional delegation went into the bomb shelters with Israeli citizens,” Cooper says. “That experience changed their outlook. It allowed us to argue, ‘At the very least, we should have theater defenses.’”

While the tactical effectiveness of the Patriot system during the war was later scrutinized, the strategic and political impact was undeniable. The experience galvanized support for missile defense, enabling Cooper to launch the Navy's sea-based missile defense program—which would evolve into one of the most successful U.S. missile defense capabilities to date, at least in land-based and sea-based modes.

Still, Cooper notes that launching the Aegis BMD program faced significant bureaucratic resistance. “Almost all of the Admirals in the Pentagon were opposed to starting the program,” he recalls, “because they were concerned that Navy cruisers and destroyers would be diverted from fleet operations to defend land targets.” Fortunately, one committed Vice Admiral supported the effort, and Chief of Naval Operations Frank Kelso agreed to accept SDI funding to initiate and expand what would become the Aegis Ballistic Missile Defense (BMD) system. That decision paved the way for a capability that now defends critical assets and locations around the world—including through land-based Aegis Ashore deployments.

Today, Cooper’s long-held vision finds fresh relevance in the Golden Dome initiative. In January 2025, President Trump signed an executive order declaring the establishment of a next-generation missile defense shield a matter of national policy. Initially referred to as “Iron Dome for America”—drawing inspiration from Israel’s highly successful system—the initiative was later renamed the Great Golden Dome by President Trump. The program now envisions a comprehensive, multi-layered defense architecture designed to counter ballistic missiles, hypersonic weapons, advanced cruise missiles, and other next-generation aerial threats.

The Golden Dome initiative is the most ambitious opportunity in decades to implement the space-based defense concepts Cooper has championed since the SDI era. The executive order specifically tasks the Department of Defense with evaluating the deployment of space-based interceptors—a direct alignment with Cooper’s original Brilliant Pebbles architecture, though multiple technical pathways are under consideration.

Unlike past efforts, which focused primarily on deterring “rogue state” actors, the Golden Dome initiative makes a bold pivot: it explicitly aims to “defend against a countervalue attack by nuclear adversaries,” including Russia and China. This represents a historic shift in U.S. missile defense policy—one that echoes the Reagan-era vision of comprehensive, civilian-protective strategic defense.

To implement this vision, the Pentagon has formed a “tiger team” to develop options of varying scope and complexity for presidential review. Some have proposed the creation of an entirely new organization to manage the initiative, likening it to a modern Manhattan Project. The Missile Defense Agency (MDA) has already received over 360 proposals from industry stakeholders, ranging from enhanced ground-based systems to space-based constellations.

Several of these concepts mirror Brilliant Pebbles directly. One proposal, for instance, involves a constellation of autonomous satellites weighing 40–80 kilograms, capable of tracking and intercepting ballistic missiles shortly after launch. This decentralized, resilient design is remarkably similar to Cooper’s SDI-era architecture.

However, the initiative faces major technical, logistical, and political challenges. As Pentagon officials acknowledge, defending the entire U.S. landmass is far more complex than merely securing borders or coastlines: “You can’t do it just at the borders and the shoreline, because intercontinental ballistic missiles can re-enter the atmosphere over Kansas.”

This geographic reality supports Cooper’s long-standing claim: only space-based systems offer a viable solution for nationwide—and truly global—defense.

Cost remains a central issue. The IRON DOME Act, introduced in the U.S. Senate, proposes $900 million specifically for space-based missile defense R&D, with additional billions earmarked for ground-based upgrades. While significant, these funds fall short of what many in today’s military bureaucracy feels is required for a full constellation deployment, reflecting the ongoing challenge of securing sustained investment. But it also represents the opportunity outlined by Cooper: i.e., focus on much smaller and lower cost space based solutions that leverage the commercial sector technologies.

Cooper highlights that leadership and bureaucratic agility are just as critical as technology. “The leadership not only needs to understand the technology,” he notes, “but be bureaucratically competent and willing to take on the challenges. I’ve never been one to avoid making up my own mind. Occasionally, you get senior people who agree with you—but there aren’t many willing to initiate transformative programs.”

On a more personal note, Cooper reflects candidly that SDI often didn’t enhance the careers of the SDI staff, “from a promotion point of view going to work for SDI was not always viewed favorably in the home service,” he admits. “We were all ‘Space Cowboys,’ and that’s how we got branded.”

This stigmatization of SDI-affiliated personnel had real consequences. Officers and civilians involved often faced career stagnation, creating a disincentive for top-tier talent to engage with the program and limiting the continuity of institutional expertise.

Cooper concludes with what he sees as the essential ingredient for success: "It takes young people who want to do the right thing, who are willing to pay the price."

Author’s Analysis: Brilliant Pebbles to Golden Dome – The Critical Opportunity

In examining the Golden Dome initiative through the lens of Cooper's experience, we find ourselves at a potential inflection point in American defense strategy. The coincidental timing is remarkable – exactly what Cooper and his colleagues have advocated for decades is suddenly receiving serious consideration at the highest levels of government.

This represents more than just a cyclical return to previous ideas. Today's geopolitical landscape, with China's rapidly expanding space capabilities, Russia's hypersonic weapons, and North Korea's nuclear provocations, creates an urgency that wasn't present even during the SDI era. The threat environment has evolved beyond ICBMs to include maneuverable hypersonic weapons, fractional orbital bombardment systems, and sophisticated countermeasures that can defeat current ground-based defenses.

What makes the current moment particularly significant is the convergence of three critical factors: advanced technology, commercial space capabilities, and political leadership with business acumen rather than bureaucratic instincts.

The technological advancement is self-evident. What required room-sized supercomputers in the early 1990s can now be accomplished with smartphone-level processing. Miniaturization, artificial intelligence, and autonomous systems have all progressed exponentially. Hypersonic intercept speeds have been demonstrated routinely by the Missile Defense Agency and foreign nations, both in space and the atmosphere. The sensors that were validated by Clementine would be considered primitive by today's standards. Modern materials science allows for lighter structures with greater durability. These advancements would make a modern Brilliant Pebbles not just feasible but far more capable than its SDI era predecessor.

Equally important is the revolution in commercial space. SpaceX has demonstrated the ability to rapidly deploy thousands of satellites, dramatically reducing launch costs while increasing reliability. The Starlink constellation has proven that large distributed satellite systems can be effectively managed. Amazon, Blue Origin, Rocket Lab, Stoke Space and other companies either can or will one day provide competitive commercial alternatives to both large constellations and reusable launch. This commercial ecosystem simply didn't exist during the SDI era.

Finally, the current administration's background in business rather than politics creates an environment potentially more receptive to innovative approaches. The emphasis on results over process, cost-effectiveness over bureaucratic comfort, and willingness to challenge established defense contractors aligns perfectly with Cooper's longstanding criticism of the defense acquisition system.

However, significant challenges remain. The Pentagon's initial framing of Golden Dome as requiring a "Manhattan Project" scale effort risks recreating exactly the bureaucratic structure that doomed previous efforts. The focus on ground-based systems in the initial funding allocations suggests an institutional bias toward familiar approaches. And the historical pattern of promising space-based defense only to dilute it through the budget process remains a very real risk.

For Golden Dome to succeed where previous efforts failed, several lessons from Cooper's experience are essential:

First, the program must maintain a laser focus on small, autonomous interceptors rather than complex centralized battle management. The distributed nature of the Brilliant Pebbles architecture was its greatest strength – no single point of failure and no vulnerable command node.

Second, commercial off-the-shelf technology should be leveraged wherever possible. The bureaucracy will inevitably push for custom-designed military-specific components, but Cooper's experience proves that commercial technology can often provide superior performance at lower cost.

Third, the organizational structure must protect the innovators from institutional resistance. All three SDI Directors supported the creation of a dedicated Brilliant Pebbles Task Force that reported directly to the SDI Director—bypassing traditional Air Force chains of command. This autonomy was seen as essential to the program’s early success. Today, that might mean an organization outside traditional Pentagon structures, perhaps leveraging the Space Force or even a public-private partnership.

Fourth, the system must be designed for iterative improvement rather than perfection from the outset. “Requirements creep” is real and a favorite son of the Pentagon establishment. The SDI approach of "build a little, test a little, learn a lot" remains the most effective way to develop revolutionary capabilities without getting bogged down in requirements creep.

The Golden Dome initiative represents potentially the last, best chance to implement the vision Cooper has championed for decades. The technological capabilities exist. The strategic need is clear. The question now is whether the political will and organizational discipline can be maintained through the inevitable bureaucratic resistance to revolutionary change.

If successful, the impact would extend far beyond missile defense. A lightweight, distributed, space-based architecture could fundamentally alter strategic stability calculations, deter aggressive behavior by adversaries, and potentially enable negotiated reductions in offensive systems – precisely the outcome that Cooper and his colleagues sought during the SDI era. The stakes could not be higher.

About Ambassador Henry F. Cooper

Ambassador Henry F. Cooper, a Clemson engineering graduate with a PhD from NYU, served in the US Air Force, was Science Advisor to the Air Force Weapons Laboratory, Deputy Assistant Air Force Secretary for Strategic and Space Systems, Assistant Director for Strategic Systems of the Arms Control and Disarmament Agency, President Reagan’s Negotiator for Defense and Space Systems with the Soviet Union and President George H.W. Bush’s Strategic Defense Initiative (SDI) Director.  In the private sector he was a Clemson Engineering Mechanics Instructor, a member of the technical staff of Bell Telephone Laboratories and R&D Associates, Senior Vice President of Jaycor, a Visiting Fellow of the Heritage Foundation, Chairman of High Frontier and Chairman of Applied Research Associates.

Additional Resources:

March 15, 2016 l The Right Side of the Cost Curve! l High Frontier 

January 8, 2019—Brilliant Pebbles Is Affordable! | High Frontier

September 25, 2018—The SBI Price is Right! | High Frontier

August 14, 2018—It’s the Law-of-the-Land! | High Frontier

April 3, 2018—The Price Is Right! | High Frontier

March 20, 2018—One More Time for “The Gipper!” | High Frontier

March 13, 2018—Time to Revive Space Defense! | High Frontier

February 6, 2018—Let’s Win One for the Gipper! | High Frontier

November 28, 2017—Boost Phase Intercept, Now! | High Frontier

July 18, 2017—Micro-satellites for Defense … Who’ll Be First? | High Frontier

February 7, 2017—President Trump: Win One for the Gipper! | High Frontier

January 31, 2017—Two Key Trump Initiatives | High Frontier

Better Defenses: Part Way Back to the Future? l High Frontier

December 4, 2014—Time to Debate About Space Based Defense? | High Frontier

July 5, 2013—The Most Cost-Effective Defense: Space Based Interceptors! | High Frontier

June 10, 2013—Can You See What’s Falling Through the Cracks? | High Frontier

May 14, 2013—The Dog Not Barking | High Frontier

Potpourri-Countering-an-Existential-Threat-To-All-We-Hold-Dear.pdf