In context: After months of testing with mixed results, SpaceX is finally ready to move forward with its Crew Dragon project. Later this year, SpaceX will use the spacecraft to launch a crewed mission to the International Space Station (ISS). This mission will transport four astronauts to the station, two of which were just added to the roster today.

These additions include American astronaut Shannon Walker and Japanese Aerospace Exploration Agency member Soichi Noguchi. The news was revealed by NASA today, along with some other details about the mission. For starters, the flight will be the first of many, as part of NASA's "Commercial Crew Program."

This program aims to make transportation between the ISS and the Earth more efficient than ever before. Ideally, commercial transportation between the two locations will lead to "expanded utility," additional research time, and "broader opportunities for discovery" aboard the station. NASA says that offloading the burden of human transportation to reliable third-party companies like SpaceX will free it up to focus on new projects, such as the tech that may one day drive "deep space missions."

The Crew Dragon's two new astronauts aren't fresh faces in this industry -- they're seasoned veterans. Walker spent a total of 163 days aboard the ISS back in 2010, and Noguchi lived there from December of 2009 to June of 2010. Walker and Noguchi will be joining two other experienced astronauts aboard the Crew Dragon: Victor Glover and Michael Hopkins. Upon arriving at the ISS, Walker, Glover, Hopkins, and Noguchi will work aboard the station for around six months before returning home.

We don't have a specific launch date for the Crew Dragon's first operational mission, but the day will be heavily dependent on the success of SpaceX's Demo-2 test, which is scheduled for May 20. Demo-2 will be the Crew Dragon's first-ever manned test flight, taking two passengers to the ISS and back as part of a 14-day expedition (which may be extended, if NASA sees fit).