Why a U.S. Golden Dome Won’t Work
President Donald Trump and Defense Secretary Pete Hegseth on May 20th, 2025. Image source here.
On May 20th, President Trump, joined by Defense Secretary Pete Hegseth in the Oval Office, announced plans for a $25B investment in a space-based missile defense system dubbed the “Golden Dome” after Israel’s notedly successful Iron Dome. The full estimated costs at the time were around $175 billion, and the promise was to upgrade a national defense system in dire need of an update. Space-based nuclear defense systems are not a new concept; they are simply the modern iteration of President Reagan’s Strategic Defense Initiative (famously dubbed “Star Wars”) and its direct descendant, the “Brilliant Pebbles” program, both of which were largely unsuccessful. However, despite modern advances in technology, the “Golden Dome” initiative is still a distant fantasy, one that is doomed to fail due to insurmountable flaws in physics, economics, and vulnerabilities.
The logic of a space-based shield is to hit and destroy a missile when it is at its weakest point. For most intercontinental ballistic missiles, that point comes during its “boost phase”, which are the first few minutes after launch when the engines are still burning. In this phase, the missile is a large, hot, slow-moving target with a bright rocket trail that is easy to track. The appeal of this strategy, known as boost-phase intercepting, is that it neutralizes the threat before it can release its multiple warheads and cloud of decoys, which confuse defenses. According to nuclear arms experts, modern missiles remain in their boost phase for less than three minutes. Therefore, after accounting for the 45-60 seconds required to detect a launch, the actual time available to make an intercept is a fleeting moment.
Since this window is so small, in order to hit that target, the defense mechanism must already be nearby. The only way to guarantee this is to place the interceptors in space—the key trait of the Star Wars and Brilliant Pebbles programs, and now the Golden Dome initiative. These interceptors, called Space-Based Interceptors (SBIs), are launched into orbit and designed to detect the bright plume of a launched missile, calculate a path, and fly at it, destroying it through a high-speed, meteor-like direct collision. However, it is obviously impossible to keep objects stationary in space, meaning that the SBIs are constantly orbiting around Earth at over 17,000 miles per hour. This constant motion means that the vast majority of interceptors will, by sheer chance, be in the wrong place at the wrong time and will be unable to reach their missile target before it exits the boost phase. This introduces what is known as the “absentee ratio”, which measures the number of interceptors that are needed in orbit for every missile that is launched, in order to ensure that interceptors are in the proper place at the proper time. Today, experts estimate that the requirement is between 500 and 1,000 interceptors in orbit just to ensure one or two are positioned for a reliable defense against a single missile. The inescapable conclusion is that to guarantee coverage over one of the world’s largest countries by land mass, a constellation of these interceptors is required.
Deploying and maintaining a fleet like this comes with a staggering cost. Creating a network that fits in the White House’s $175 billion funding constraint would be sloppy, time-consuming, and reach nowhere near the levels of interceptors that would be required to defend a legitimate attack from the growing arsenals of our adversaries. Reports from the Congressional Budget Office estimated an initial price tag of nearly $542 billion. However, this cost could be upped even higher, as adversaries could overwhelm the investment by simply building more missiles, whose per unit cost is drastically lower than that of another interceptor. This has led many to realize that the U.S. cannot simply outspend its opponents, as a logical adversary will recognize that they hold the cost advantage and utilize that against the U.S.
The “Golden Dome” is therefore an unworkable concept, defeated by illogical physics, a disastrous cost-benefit ratio, and simple and effective countermeasures. A smarter path would be to invest more in ground-based defenses, which are both more practical and more cost-effective when compared to space-based defense mechanisms. While thousands of space-based interceptors are required to diffuse a single missile, that same work can be done with just 2 to 4 ground-based interceptors. A ground-centric defense mechanism, therefore, could provide similar strategic protection for just a fraction of the cost of a Golden Dome. Ultimately, the idea of Star Wars, though fun, is drastically far-fetched, inefficient, and costly.