Elon Musk’s SpaceX is gearing up to send a crew of astronauts to the International Space Station for the fourth time.

The mission, dubbed Crew-3, will carry NASA astronauts Raja Chari, Tom Marshburn and Kayla Barron, along with European Space Agency astronaut Matthias Maurer, to the ISS for a six-month stay in orbit.

The spaceflight, moved to Wednesday from Sunday because of weather, will be the first for three of the four crew members.

The veteran on the mission is Marshburn. The doctor and former NASA flight surgeon, making his third trip to space, said this research could one day answer bigger questions about human existence.

“It’s every one of us who has looked into the night sky and wondered, ‘How does the universe work, and how did life come to our planet Earth?'” Marshburn told ABC News.

Barron, an astronaut who has experience on submarines, said her time in Navy has helped prepare her for this moment — and that she made a playlist for the ride out.

“There are some strong millennial favorites on my playlist and throwbacks to the ’90s,” she joked.

They will launch aboard SpaceX’s Crew Dragon spacecraft and Falcon 9 rocket.

The crew is scheduled to spend 22 hours in the capsule before docking with the ISS. The team decided to call the new capsule “Endurance” — a tribute to the human spirit and a historic sailing vessel used by Antarctic explorer Ernest Shackleton.

SpaceX launched two NASA astronauts to the ISS successfully for the first time in June 2020, which cleared them to continue conducting flights with their rocket and Crew Dragon. It was the first crewed launch to depart from American soil in nearly a decade.

Last month SpaceX’s Inspiration4 mission made history as civilians traveled the greatest distance away from Earth — 367 miles — even farther than the International Space Station.

But on that flight they discovered an issue with the toilet inside the Crew Dragon that almost hampered the Crew-3 launch. A tube became unglued and spilled urine onto fans beneath the floor.

“It had no impact on Inspiration4 at all,” William Gerstenmair, SpaceX’s vice president, said during a press conference. “We didn’t really even notice it, the crew didn’t notice it, until we got the vehicle back and we looked under the floor and we saw the fact that there was contamination.”

Engineers eventually fixed the problem.

SpaceX is contracted to launch up to six crewed flights for NASA, with two more scheduled for 2022.