CAPE CANAVERAL, Fla. (WFLA) — SpaceX launched its second private spaceflight to the International Space Station on Sunday.

The Falcon 9 rocket, topped with the Dragon capsule, was rolled out to the launch pad at Kennedy Space Center on Thursday. SpaceX launched the rocket on Sunday at 5:37 p.m.

SpaceX collaborated with Axiom Space for its Ax-2 mission. The Houston-based company wants to build and operate its own commercial space station – a possible replacement for the ISS, which NASA plans to retire by 2031.

Four crew members climbed aboard Dragon, including Mission Commander Peggy Whitson, who has spent more time in space than any other American. John Shoffner, described by Axiom as a “STEM advocate, business pioneer, and life-long space enthusiast,” paid for the opportunity to pilot the spacecraft.

Two astronauts from Saudi Arabia round out the crew. Rayyanah Barnawi, a biomedical researcher, and Ali AlQarni, a fighter pilot, will serve as mission specialists. Barnawi will be the first-ever Saudi woman in space.

The crew will bring over 20 experiments with them to space, studying topics that range from artificially-generated rain, to student-led projects that marry science with the arts. One experiment will research how stem cells multiply in microgravity.

“Potentially we can use this technology, maybe produce these stem cells in space, harness that microgravity to differentiate them. And then use stem cells in cell therapy here on earth,” Dr. Ryan Reeves of the ISS National Lab told NBC affiliate WESH.