Private spaceflight specialist Axiom Space on Wednesday announced a deal with SpaceX that added three more crewed flights to the International Space Station, bringing its total planned missions through Elon Musk’s company to four.

“We are beyond excited to build upon our partnership with Axiom to help make human spaceflight more accessible for more people,” SpaceX president Gwynne Shotwell said in a statement. “A new era in human spaceflight is here.”

Houston-based Axiom had previously announced its Ax-1 mission would launch with SpaceX’s Falcon 9 rocket and Crew Dragon capsule, and now the Ax-2, Ax-3 and Ax-4 missions will as well.

Ax-1 is currently scheduled to launch in January 2022.

Musk’s company has flown three Crew Dragon flights to the space station to date, all under NASA’s Commercial Crew program and carrying government astronauts. SpaceX has flown 10 astronauts to orbit so far, with a full schedule of both government and private Crew Dragon missions in the year ahead.

“SpaceX has blazed the trail with reliable, commercial human launch capability and we are thrilled to partner with them on a truly historic moment,” Axiom CEO Michael Suffredini said in a statement.

While Axiom declined to comment on the financial details of the deal, NASA is paying SpaceX about $55 million per astronaut to fly to the space station – giving an idea of the steep cost of a private flight to orbit. Although SpaceX is providing the rocket and capsule, Axiom is leading the mission’s management from training to the return to Earth.

Axiom calls these private flights “precursor missions,” as the unicorn space company is building habitable modules that will connect to the ISS, as well as operate independently in orbit.