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Elon Musk’s SpaceX is planning to launch four astronauts to the International Space Station from Florida on Wednesday, as the company keeps up a steady pace of crewed missions.

Known as Crew-3, the mission for NASA will bring the quartet to the ISS for a six-month stay in orbit on the research laboratory. SpaceX is launching the astronauts in its Crew Dragon capsule on top of a Falcon 9 rocket, with liftoff scheduled for 9:03 p.m. ET.

The company’s livestream with NASA is expected to begin about four hours before launch.

The launch is SpaceX’s third operational crew launch for NASA to date, and the first by the latest addition to its fleet of Crew Dragon capsules, named “Endurance” by the Crew-3 astronauts. The Crew-3 mission will bring the number of astronauts SpaceX has launched to 18.

The Crew-3 mission will carry four astronauts, three American and one German: NASA astronauts Raja Chari, Tom Marshburn, Kayla Barron, and European Space Agency astronaut Matthias Maurer. This is the first spaceflight for three of the crew: Chari, Barron, and Maurer.

SpaceX developed its Crew Dragon spacecraft and fine-tuned its Falcon 9 rocket under NASA’s Commercial Crew program, which provided the company with $3.1 billion to develop the system and launch six operational missions.

Commercial Crew is a competitive program, as NASA also awarded Boeing with $4.8 billion in contracts to develop its Starliner spacecraft — but that competing capsule remains in development due to an uncrewed flight test in December 2019 that experienced significant challenges.

Crew-3 represents the third of those six missions for SpaceX, with NASA now benefiting from the investment it made in the company’s spacecraft development.

NASA emphasizes that, in addition to the U.S. having a way to send astronauts to space, SpaceX offers the agency a cost-saving option as well. The agency expects to pay $55 million per astronaut to fly with Crew Dragon, as opposed to $86 million per astronaut to fly with the Russians. NASA last year estimated that having two private companies compete for contracts saved the agency between $20 billion and $30 billion in development costs.

Endurance is a new Crew Dragon capsule debuting for this mission. Previously, capsules “Resilience” and “Endeavour” have flown astronauts, and SpaceX expects to add a fourth Crew Dragon early next year.