Instead, the $252 billion option would include additional Patriot missile batteries and air-control squadrons, dozens of new aircraft, and next-generation systems to defend against drone and cruise missile attacks on major population centers, military bases, and other key areas.
At the other end of the spectrum, Harrison writes that the "most robust air and missile defense shield possible" will cost some $3.6 trillion through 2045, nearly double the life cycle cost of the F-35 fighter jet, the most expensive weapons program in history.
"In his Oval Office announcement, President Trump set a high bar for Golden Dome, declaring that it would complete 'the job that President Reagan started 40 years ago, forever ending the missile threat to the American homeland and the success rate is very close to 100 percent,'" Harrison writes.
The numbers necessary to achieve this kind of muscular defense are staggering: 85,400 space-based interceptors, 14,510 new air-launched interceptors, 46,904 more surface-launched interceptors, hundreds of new sensors on land, in the air, at sea, and in space to detect incoming threats, and more than 20,000 additional military personnel.
SpaceX's Starship rocket could offer a much cheaper ride to orbit for thousands of space-based missile interceptors. Credit: SpaceX
No one has placed missile interceptors in space before, and it will require thousands of them to meet even the most basic goals for Golden Dome. Another option Harrison presents in his paper would emphasize fast-tracking a limited number of space-based interceptors that could defend against a smaller attack of up to five ballistic missiles, plus new missile warning and tracking satellites, ground- and sea-based interceptors, and other augmentations of existing missile-defense forces.
That would cost an estimated $471 billion over the next 20 years.
Supporters of the Golden Dome project say it's much more feasible today to field space-based interceptors than it was in the Reagan era. Commercial assembly lines are now churning out thousands of satellites per year, and it's cheaper to launch them today than it was 40 years ago.
A report released by the nonpartisan Congressional Budget Office (CBO) in May examined the effect of reduced launch prices on potential Golden Dome architectures. The CBO estimated that the cost of deploying between 1,000 and 2,000 space-based interceptors would be between 30 and 40 percent cheaper today than the CBO found in a previous study in 2004.
But the costs just for deploying up to 2,000 space-based interceptors remain astounding, ranging from $161 billion to $542 billion over 20 years, even with today's reduced launch prices, according to the CBO. The overwhelming share of the cost today would be developing and building the interceptors themselves, not launching them.