Retired NASA astronaut Mark Kelly has lambasted President Trump's proposal to create a Space Force, saying the Air Force already does the tasks Trump is talking about.

"This is a dumb idea," Kelly wrote on Twitter. "The Air Force does this already. That is their job. What’s next, we move submarines to the 7th branch and call it the “under-the-sea force?”

Kelly, who has been mentioned as a possible Democratic congressional candidate in the past (he is married to former Rep. Gabby Giffords) was referring to the Air Force Space Command (AFSPC), a unit of the Air Force focused on space.

MASSIVE MARS DISCOVERY: ORGANIC MOLECULES 'FUNDAMENTAL TO OUR SEARCH FOR LIFE' FOUND BY NASA ROVER

According to the AFSPC's website, its mission is to "to provide resilient and affordable space and cyberspace capabilities for the Joint Force and the Nation." It has more than 36,000 people working at 134 locations around the world to support this mission.

Headquartered at Peterson Air Force Base, in Colorado, the AFSPC's capabilities include facilities and range safety control for the conduct of Deparment of Defense, NASA and commercial launches, command and control of all Deparment of Defense satellites.

Its capabilities also include "continuous global coverage," space surveillance on satellites and space debris. "Maintaining space superiority is an emerging capability required to protect U.S. space assets," AFSPC states in its website.

On Monday, Trump announced he is directing the Pentagon to create a new "Space Force" as an independent military service branch aimed at ensuring American supremacy in space, a directive that seemed to take Defense officials by surprise. Creating a new joint military command is largely the purview of Congress, which would have to provide the authority and any funding or shifting of money to a new unit.

The Department of Defense is already in the middle of a congressionally mandated review of the space force issue. The study began in March, with an interim review due in August and a final report due December 31. It's not clear if the president's comments Monday were meant to override or influence that study.

In a March document outlining the review, the Pentagon said it has already made organizational changes to beef up the stature of the Space Force, but is reviewing others. The document sent to Congress said the review will look at research, capabilities, acquisition and joint warfighting needs, and will assess "whether the Space Corps concept should be implemented."

JEFF BEZOS SAYS WE NEED TO LEAVE EARTH

Others weigh in

Other experts have weighed in on the creation of a Space Force, with some saying it could be a good idea if done properly.

"This could be politically very difficult to do," Dr. John L. Crassidis, Samuel P. Capen Chair professor at the University of Buffalo, told Fox News. "I don't necessarily think having one agency look at space is a bad idea if it's done right."

Dr. Crassidis added that space debris is a huge issue, saying "there's a good possibility that a collision [with space debris] in the next 20 to 30 years could occur."

As of 2013, NASA pointed out there were more than 500,000 pieces and they have the potential to do some serious damage to space equipment, including satellites or even spacecraft.

Buzz Aldrin, the second man to walk on the Moon, said the conversation about the proposed Space Force is leading to "interesting times," though Aldrin, who was caught on camera looking baffled when Trump spoke about space last year, did not expand on what he meant by that.

In October 2017, Secy. of Defense James Mattis wrote letters to several congressmen, including Sen. John McCain (R.-Az.), the Chairman of the Committee on Armed Services, and said he opposed "the creation of a new military service and additional organizational layers at a time when we are focused on reducing overhead and integrating joint warfighting functions."

Fox News has reached out to the White House with a request for comment on this article.

The Associated Press contributed to this report. Follow Chris Ciaccia on Twitter @Chris_Ciaccia