A new report by the Congressional Budget Office (CBO) estimates that the Defense Department could spend hundreds of millions, or billions, of dollars to form a “Space National Guard” to complement the recently formed Space Force depending on how large it plans the force to be.

Since the sixth military branch was established in the fiscal year 2020 National Defense Authorization Act, questions have abounded as to whether a Space National Guard might be set up in the near future. In February, senior leaders of the National Guard Bureau proposed a plan that would convert existing Air and Army National Guard units that work in space to form a new Space National Guard. However, the Department of the Air Force – under which the new Space Force falls – has not yet shared any details of when, or whether, a Space National Guard will be created.

The CBO report, released June 2, analyzes two options – the first considering if the existing space-related units in the Army and Air National Guard were transferred into the Space National Guard, and the second considering if the Space National Guard were to reach a size that was proportional to the Air National Guard’s size relative to the Air Force, about 32 percent the size of the active component.

Under the first proposal, about 1,500 personnel would transfer from the Air and Army National Guards into a new Space National Guard, along with an assumed 50-90 personnel in the training pipeline, the report said. Creating this size of a Space National Guard would require additional annual operation and support costs of $100 million, plus $20 million for onetime construction costs.

“It is unclear to what degree such a force would require additional administrative overhead,” the CBO said, noting that each state or territory that would be affected by transfers would already be organized to administer and command those units via the existing Guard structure. “However, it is likely that a small number of additional personnel would be needed in each state or territory affected, as well as some personnel for national functions,” the report said, estimating about 260 new personnel would come into the new Guard.

It would require 4,900 to 5,800 personnel to form a Space National Guard whose size relative to the Space Force would be similar to that of the Air National Guard to the Air Force, the report said. That would include the space-related Air and Army National Guard Units described in the first option, plus another 3,400 to 4,300 full-time and part-time positions. Using numbers based on average operation and support costs per capita for Air National Guard personnel, the CBO estimated such a size force would cost between $355 million to $460 million per year for personnel costs, plus about $30 million per year to support national functions.

The larger Space National Guard would additionally require $400 million to $900 million in onetime costs to equip the new units and build new facilities such as armories.