Crew members have worked years with companies to get here and they said they can not wait for the flights to begin next year. Boeing said earlier this week it would carry out a test flight of the Starliner vehicle without humans later this year or in early 2019, after it suffered an issue with the capsule's launch abort system during a test in New Mexico in June, according to SpaceNews.
More astronauts will be announced to join the crews at a later date, NASA said.
"For the first time since 2011, we are on the brink of launching American astronauts on American rockets from American soil", Jim Bridenstine, NASA administrator, said.
NASA has always been working on developing its commercial crew programme while it can focus on its space exploration projects, the report added. He retired from NASA in 2011 and has been an integral part of Boeing's CST-100 Starliner program.
These US astronauts previously flew aboard Russian spacecraft to get to the ISS.
Boe is a former shuttle pilot; Mann will be making her first trip into space.
He logged more than 40 days in space.
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The test flights and missions aboard Boeing's CST-100 Starliner and SpaceX's Crew Dragon spacecraft, slated for as early as April 2019, will "begin a new era in America spaceflight", the US space agency said.
United States astronauts have been relying on Russian capsules to travel to the space station, with each seat costing NASA as much as $82 million (€71 million). NASA astronaut Bob Behnken, an experienced spacewalker who flew on two shuttle missions, will strap into the Crew Dragon alongside former shuttle pilot Doug Hurley.
On the first operational mission to the International Space Station, Sunita Williams and Josh Cassada would fly for Boeing.
The astronauts assigned to crew the first flight tests and missions of the Boeing CST-100 Starliner and SpaceX Crew Dragon acknowledge the media upon introduction at NASA's Johnson Space Center in Houston, Texas, U.S., August 3, 2018.
The 1997 electrical engineering master's recipient has been selected by NASA to fly aboard Boeing's first commercial crew flight test, which is expected to lift off from Florida in the middle of 2019. Behnken, Boe and Hurley have each flown two shuttle missions, logging four weeks in space apiece. SpaceX's manned test flight will feature two NASA astronauts.
The contracts for travel to the International Space Station were awarded in 2014. He is the director of Crew and Mission Systems for Boeing's Commercial Crew Program. Between the end of the space shuttle program and the start of commercial crew operations, NASA's crew members have and are continuing to launch to the space station on Russian Soyuz spacecraft.
Boeing's and SpaceX's commercial spacecraft may also open the space station - and more broadly, Earth orbit - to more privately-funded visitors and spaceflight participants from countries that do not have their own domestic crewed spacecraft and rockets.