CBO Estimates $1.2 Trillion Cost For Proposed Golden Dome Missile Defense System

' The estimate totals $1.191 trillion over a 20-year period. This figure is more than double the projection CBO issued last year. Deploying and sustaining a constellation of 7,800 space-based interceptors accounts for $743 billion of the total, or more than 60 percent.

The space-based layer alone would cost $723 billion to acquire and an additional $1 billion per year to operate and maintain. Even with this investment, the interceptors would be capable of engaging only 10 intercontinental ballistic missiles simultaneously.

The estimate breaks down into six main elements including the space-based interceptor constellation, upper and lower wide-area surface sites, regional sectors, self-defense for four existing surface sites, a space-based satellite constellation for tracking targets, and ancillary costs.

Surface site and regional sector costs primarily involve expanding existing land- and sea-based systems such as Aegis Ashore, Terminal High Altitude Area Defense, and the Next Generation Interceptor.

CBO calculated an average cost of $22 million per space-based interceptor satellite. That figure covers both the initial 7,800 interceptors and the nearly 1,600 replacements required each year due to the satellites' five-year service life. The need for periodic replacement stems from atmospheric drag at the low Earth orbit altitudes of 300 to 500 kilometers where the interceptors must operate to reach targets during the boost phase within three to five minutes.

Launch costs are based on $500 per kilogram using next-generation heavy-lift rockets such as SpaceX Starship. Even at that reduced rate, launch expenses account for less than 5 percent of the total cost for the space-based layer. The size of the constellation is driven by the requirement to maintain sufficient interceptors in position over potential intercontinental ballistic missile launch locations given the characteristics of low Earth orbit motion.