President Trump on Tuesday formally directed the Department of Defense to draft legislation creating a so-called Space Force within the U.S. Air Force – in a bid to launch the first new branch of the military in more than 70 years.

Officially known as Space Policy Directive 4 (SPD-4), the directive would put Trump’s Space Force on similar ground as the U.S. Marine Corps, which is part of the Navy, but stipulates that it could become its own separate department in the future. Cost details are expected to be included in the 2020 budget proposal Trump sends Congress next month.

"The United States considers freedom to operate in space a vital national interest, one that is fundamental to our prosperity and security," Chief Pentagon Spokesperson Charles E. Summers Jr., said in a statement provided to Fox News. "With Space Policy Directive-4, President Trump is posturing the United States to compete, deter, and win in a complex multi-domain environment characterized by great power competition."

TRUMP ORDERS ESTABLISHMENT OF 'SPACE FORCE' AS 6TH BRANCH OF MILITARY

The directive was developed by the National Space Council alongside members of the Pentagon, Joint Chiefs of Staff, Office of the Director of National Intelligence, National Security Council, Office of Management and Budget, and the White House Counsel's Office.

Space Force will also be represented on the Joint Chiefs of Staff and overseen by an Air Force undersecretary for space.

“There are 1,000 decisions that have to be made to be able to work out the intricate details of how we move forward, how we establish a service within the Department of the Air Force,” said Gen. David Goldfein, chief of staff of the U.S. Air Force at the Washington think-tank Brookings Institution Tuesday .

The proposal, which still would need congressional approval, comes just over two months after Trump signed a memorandum getting the process started.

It would follow the U.S. Space Command, which existed from 1982 to 2002 but was moved under U.S. Strategic Command after the 9/11 attacks.

The current U.S. Air Force Space Command resides at Peterson Air Force Base in Colorado Springs, Colo., about 20 miles from the U.S. Air Force Academy. There are no current plans to establish a new service academy for Space Force. Like the Marines who draw from midshipmen at the U.S. Naval Academy, it is presumed any future Space Force officers will come from the Air Force Academy.

MARS 'TERROR,' FUTURE MOON MISSIONS AND AN EPIC JOURNEY TO THE SUN: 2018'S YEAR IN SPACE

The biggest question now surrounding the space force is: What would it actually do?

While some online commentators envision something akin to Star Trek or Battlestar Galactica, the reality would – at least in the foreseeable future – be more down to earth.

Inside the Pentagon, there is a small but vocal minority pushing programs such as anti-satellite weapons, missile detection capability and space-based solar power to counter mounting space threats from Russia and China. But others argue that the biggest danger to future space exploration is the debris floating around Earth’s orbit now.

CLICK HERE TO GET THE FOX NEWS APP

Whatever the mission, experts tend to agree that a “space force” won’t be something that will be patrolling the final frontier anytime during Trump’s current presidential term.

“This is something that is going to take a long time to get running, three to five years if things run smoothly and this actually gets through Congress,” John Crassidis, a professor of mechanical and aerospace engineering at the University of Buffalo, told Fox News.

The last time a new branch of the military was created was in 1947, when the National Security Act created the Air Force in the wake of World War II.

Fox News' Lucas Tomlinson and The Associated Press contributed to this report.