According to the Congressional Budget Office (CBO), reduced launch costs over the last few decades could potentially lower estimates for a space-based missile defense layer by up to 40%. In a letter dated May 5 addressed to Senate lawmakers, CBO highlighted that a proposed Golden Dome missile defense shield capable of addressing threats from regional adversaries such as North Korea, as well as militaries with comparable capabilities like China and Russia, would likely necessitate significantly more sensors and interceptors than previously calculated. This could lead to a much higher overall price tag.
In its correspondence, the CBO stated, “Such a defense could require a more expansive SBI capability than the systems examined in the previous studies.” The letter was directed to Senators Deb Fischer of Nebraska and Angus King of Maine, indicating that further analysis would be necessary to quantify the changes stemming from updated threat assessments.
Historically, the Pentagon has explored options for creating constellations of space-based systems designed to intercept or destroy enemy missiles, a concept initially promoted by the Reagan administration through its Strategic Defense Initiative, aimed at neutralizing Soviet missiles from space. This initiative was ultimately abandoned due to technical challenges and policy concerns.
Renewed interest in space-based interceptors was stimulated by an executive order signed by President Donald Trump in January that called for an advanced, layered missile defense network, termed the Golden Dome, intended to defend against threats both on the ground and from space.
According to the CBO, previous studies, including its own report from 2004 and a 2012 study by the National Research Council, provided cost estimates for space-based interceptors (SBI) ranging from $264 billion for 1,300 interceptors to $831 billion for 2,000 interceptors. Central to these estimates were launch costs, which were projected to be between $9,800 and $10,600 per pound. This led to a 20-year launch cost projection of between $116 billion and $335 billion in 2025 dollars.
The CBO found that since the early 2000s, launch costs have decreased by 90%, significantly reducing their overall share of an SBI program’s total costs. The updated estimates indicate that launch services would account for less than 10% of total costs over 20 years, a decrease from approximately 40% in earlier estimates. Consequently, the lower-end cost projection now stands at around $161 billion, while the upper end is at approximately $542 billion.
Despite the lower launch costs, the CBO cautioned that the actual costs of an interceptor architecture designed for a broad range of missile defense needs would likely exceed the estimates from 2004 and 2012, regardless of the reduced launch prices. The office is currently conducting a more in-depth analysis of the overarching costs associated with the constellation.
The Pentagon is anticipated to request funding for the Golden Dome initiative in its fiscal 2026 budget, and a proposed budget reconciliation package from House Republicans has earmarked $24.7 billion for missile defense, which includes $5.6 billion specifically for space-based interceptors.
The CBO suggested that if the Pentagon chooses to focus its SBIs primarily on “rogue adversaries,” it could alter the size of its SBI constellation and potentially reduce related costs. The institute noted, “The SBI system would probably have to be larger than those assumed in the two earlier studies — because of increases in North Korea’s capabilities — but not as large as would be necessary to counter Chinese or Russian attacks.”
Courtney Albon, the author of the report, has been reporting on the U.S. military since 2012, focusing on the Air Force and Space Force, and covering various defense acquisition, budget, and policy challenges.
