Brendan Byrne A SpaceX Falcon 9 rocket launches a Crew Dragon capsule from NASA's Kennedy Space Center in Florida on Wednesday. The Ax-4 mission is the fourth private spaceflight for the Houston-based commercial company, which is flying four astronauts on a two-week trip to the International Space Station. John Raoux/AP hide caption toggle caption How the U.S. became highly reliant on Elon Musk for access to space It's the fourth mission brokered by the Houston, Texas-based commercial space company Axiom Space. The company works with SpaceX for rides to the International Space Station and coordinates with NASA for the usage of the I.S.S. for its astronauts. The European Space Agency and the governments of the participating astronauts also contributed to the mission. The Ax-4 launch comes after multiple issues delayed the mission. First, an attempt to launch earlier this month was waived off due to weather. Then, the crew's rocket — SpaceX's Falcon 9 — developed a leak. Sponsor Message The mission was then delayed for nearly two weeks as NASA and its Russian space station partner, Roscosmos, investigated a leak on the station's Zvedzda service module, one that has previously been repaired and monitored by flight controllers for years. NASA said the pressure in the module was stable, and the crew was given the all-clear to launch. Axiom's Peggy Whitson is serving as commander. Whitson, a retired NASA astronaut, has set numerous spaceflight records, including the most cumulative time in space by a U.S. astronaut. This mission will add to her 675-day record.