Liftoff! Four people are on their way to the space station on NASA's Crew-8 mission

A SpaceX Falcon 9 rocket thundered off the launch pad at the Kennedy Space Center in Florida during a fiery nighttime liftoff just before 11 p.m. ET on Sunday. Four people were aboard the capsule as NASA's Crew-8 mission gets underway.

For the next 28 hours, the capsule will race to the International Space Station as it orbits more than 250 miles above the Earth. Once it catches up, it'll dock autonomously around 3 a.m. ET on Tuesday and the crew will spend the next six months on the orbital laboratory.

There was some concern in the minutes before launch about a "small crack" seen in a seal when the capsule's side hatch was closed. SpaceX told the crew there would be no concern during liftoff - but on the capsule's return when the soaring temperatures of re-entry could pose safety problems. After analysis, SpaceX's engineers said they were confident it would not be an issue for the mission.

The Crew-8 mission members are three NASA astronauts and a Russian cosmonaut. The commander is NASA's Matthew Dominick, pilot Michael Barratt, mission specialists Jeanette Epps and Alexander Grebenkin of Roscosmos, Russia's space agency.

This is the first spaceflight for Dominick, Epps and Grebenkin. It's the third for Barratt.

During their time on the I.S.S., NASA says the crew plans to conduct more than 200 experiments and scientific demonstrations. These include studying the effects of microgravity and UV radiation on plants, using stem cells to create models to study degenerative disease and testing whether wearing pressure cuffs on the legs could prevent fluid shifts and reduce health problems in astronauts.

They'll relieve the four people on the Crew-7 mission which launched last August and is set to splashdown off the Florida coast in about a week.

The I.S.S. has been continuously occupied since November 2000. Typically seven people are aboard as the football field-sized station circles the earth at five miles per second.

This is the 13th time SpaceX has launched humans into space since 2020 and comes a day after the fifth anniversary of SpaceX's first uncrewed demonstration launch of the Crew Dragon capsule. And, with this mission, the private company has sent 50 people into orbit. By comparison, during the Apollo era (including the lunar missions, Skylab launches and Apollo-Soyuz), NASA launched 45 into space.

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