CSIS analyst Todd Harrison estimated the cost of three options — a Space Corps, a Space Force Lite and a Space Force Heavy.

WASHINGTON — The takeaway from new cost estimates for establishing a new military service for space is that there is no cheap way to build a Space Force.

Todd Harrison, director of defense budget analysis and senior fellow at the Center for Strategic and International Studies, unveiled a highly anticipated report on Monday, detailing cost estimates for standing up a Space Force as a separate military branch. Harrison made headlines in September when he criticized Air Force Secretary Heather Wilson’s estimate — $13 billion over five years to establish a new service and a space command — as overinflated.

Harrison estimated it would cost the Pentagon an additional $1.5 billion to $2.7 billion over five years to stand up a new service, based on the assumption that more than 96 percent of the cost would be covered from existing budget accounts within DoD. Harrison’s numbers, however, are hard to compare directly with the Air Force secretary’s because they do not include costly items that Wilson put into her proposal, such as a Space Command and additional programs and people she argued would be needed to fight rising space rivals China and Russia.

Harrison laid out cost numbers for three options — a Space Corps, a Space Force Lite and a Space Force Heavy. The total annual budget of the new service would range from $11.3 billion to $21.5 billion under the three options. None includes the National Reconnaissance Office whose size and budget are classified.

The CSIS report does not include the cost of standing up a new combatant command for space, U.S. Space Command, or a Space Development Agency because these are separate policy decisions and both could be created with or without a new military service, Harrison said on Monday at at news conference. His analysis assumes that the military will continue to do what it currently does in space. “That’s a separate decision, if you want to do more in space,” he said. “I just focused on the reorganization.” The Space Development Agency is a high priority for Pentagon leaders but Harrison chose to not include it in his report because the mission or purpose of the agency is “not well defined yet.”

The first option, a Space Corps within the Department of the Air Force, would essentially be staffed by current airmen — a 27,300 total workforce including military and civilians. About $11 billion of its $11.3 billion annual funding would come from existing Air Force accounts.

The second option, a limited but independent Department of the Space Force is what Harrison calls Space Force-Lite. It include everyone from the Space Corps plus additional people from the Army and the Navy, for a total workforce of 35,800 and an annual budget $13.4 billion, $13 billion of which would come from other services’ accounts.

The third option, a Department of the Space Force, or Space Force-Heavy, adds missile defense activities and elements of the Defense Information Systems Agency, for a total workforce of 48,500 and an annual budget $21.5 billion, of which $500 million would be new funding. The Heavy option assumes the Space Force would have its own bases, recruiting and training organizations. The Space Force would not have its own service academy or professional military schools.

Harrison stood by his previous criticism of Wilson’s Space Force cost memo as a poison pill. “They did it with the largest possible scope,” he said. Wilson has yet to explain why she believes and additional 10,000 people and a billion-dollar building are needed for U.S. Space Command, said Harrison. “This begs the question: We have people doing those jobs at U.S. Strategic Command, why not move them over?”

The obvious conclusion from Harrison’s study is that the size and budget of a new military service for space can vary considerably depending on the scope of the reorganization.

According to DoD sources, of Wilson’s $13 billion estimate, about half is for U.S. Space Command. Critics of her proposal insist that most of the Space Force and Space Command personnel should be transferred from existing organizations, but there are likely to be “huge inefficiencies” associated with moving thousands of people around, one official said. “There’s huge inefficiency with standing up a new department and all the functions you have to replicate.”

Deputy Defense Secretary Patrick Shanahan told reporters last week that he estimated the cost of a new service would be in the “single digit” billions. Harrison said he did not share any of his numbers with Shanahan in advance of the CSIS study’s release on Monday. “We don’t know what he meant by single-digits,” said Harrison. “That could be anywhere from 1 to 9 billion, a pretty broad range.”

As to whether any of the Space Force models has any chance of getting through Congress next year, Harrison said “at this point it may be a coin toss.” A lot depends on how the Trump administration sells it, how it scopes the new service, “how disruptive it might be perceived to be, and whether it will be seen as Trump’s Space Force or something the military is getting onboard with,” said Harrison. “That would make a big difference in the House.”