HOUSTON — President Donald Trump fired off a celebratory tweet today to laud NASA's first astronaut crews to fly on private spacecraft built by Boeing and SpaceX, a message that also appeared to hail the president's proposed military Space Force.

"NASA, which is making a BIG comeback under the Trump Administration, has just named 9 astronauts for Boeing and Spacex space flights," Trump wrote on Twitter. "We have the greatest facilities in the world and we are now letting the private sector pay to use them. Exciting things happening. Space Force!"

NASA has unveiled the first astronaut crews to fly on private spaceships built by SpaceX and Boeing. The astronauts are: (from left to right) Victor Glover, Mike Hopkins, Bob Behnken, Doug Hurley, Nicole Aunapu Mann, Chris Ferguson of Boeing, Eric Boe, Josh Cassada and Sunita Williams.
NASA has unveiled the first astronaut crews to fly on private spaceships built by SpaceX and Boeing. The astronauts are: (from left to right) Victor Glover, Mike Hopkins, Bob Behnken, Doug Hurley, Nicole Aunapu Mann, Chris Ferguson of Boeing, Eric Boe, Josh Cassada and Sunita Williams.
Credit: NASA/Bill Ingalls

NASA announced the nine astronauts that will fly on the first crewed flights of SpaceX's Crew Dragon and Boeing's CST-100 Starliner spacecraft during a ceremony here at the agency's Johnson Space Center. The group includes eight current NASA astronauts and one Boeing astronaut. They will be the first Americans to launch into space from U.S. soil since NASA's space shuttle program retired in 2011.Since then, the U.S. has relied on Russia's Soyuz spacecraft to carry Americans space. [Meet NASA's 1st Commercial Crew Astronauts]

Trump's Twitter praise for the astronauts did appear to gloss over the fact that NASA is actually paying SpaceX and Boeing to fly American astronauts. The tweet's second sentence seems to suggest that Boeing and SpaceX are paying the government to fly the missions. In fact, NASA is paying Boeing and SpaceX billions to fly Americans to and from the International Space Station.

It is true, however, that SpaceX and Boeing are paying to use some facilities owned by NASA and the U.S. Air Force. SpaceX has leased NASA's historic Launch Pad 39A at the Kennedy Space Center (KSC) in Cape Canaveral, Florida to launch Falcon 9 and Falcon Heavy rockets. The company also uses launchpads at the nearby Cape Canaveral Air Force Station (CCAFS) and Vandenberg Air Force Station in California.

Boeing has leased two of NASA's old space shuttle hangars at KSC, known as Orbiter Processing Facilities, to build its Starliners and house two small robotic X-37B space planes it built for the Air Force. Boeing is also part of the United Launch Alliance (along with Lockheed Martin), a launch services company that uses launchpads at both CCAFS and Vandenberg.

Trump's statement that NASA is making a "BIG comeback" under his administration could be referring to the three Space Policy Directives Trump has issued over the last six months. In December, Trump signed Space Policy Directive 1 to set the moon as NASA's next goal for astronauts. His Space Policy Directive 2, signed in May, was aimed at streamlining regulations for commercial space industry. In June, Trump signed Space Policy Directive 3, directing the Commerce Department to take charge of space traffic control operations.

Trump's congratulatory tweet ends with an emphatic "Space Force!" signoff, referring to the new space-centered branch of the military he has ordered the Pentagon to create. While some NASA astronauts are military officers, NASA itself is a civilian space exploration agency. In June, Trump directed the Department of Defense to form a Space Force as the sixth branch of the U.S. military.

Boeing's first crewed Starliner test flight will be flown by NASA astronauts Eric Boe and Nicole Aunapu Mann and Boeing astronaut Chris Ferguson in mid-2019. Ferguson, a former NASA astronaut and space shuttle commander, is Boeing's director of crew and mission systems.

SpaceX's first crewed test flight on the Crew Dragon will be flown by astronauts Bob Behnken and Doug Hurley in April 2019.

If those missions go well, astronauts Mike Hopkins and Victor Glover will fly the first operational Crew Dragon flight to the International Space Station, while astronauts Sunita Williams and Josh Cassada will fly the first operational CST-100 Starliner mission.

Trump wasn't the only one heralding NASA's commercial crew announcement today. Vice President Mike Pence, who leads the National Space Council that has helped shape the Trump administration's space policies, also weighed in.

"Congrats to the first Americans who will travel on American rockets from American soil to the @Space_Station since 2011 aboard the @SpaceX #Dragon and @Boeing #Starliner," Pence wrote.

Email Tariq Malik at tmalik@space.com or follow him @tariqjmalik. Follow us @SpacedotcomFacebook and Google+. Original article on Space.com.