After a scrubbed attempt this week, NASA’s SpaceX Crew-10 mission successfully lifted off Friday evening from the Kennedy Space Center in Florida headed for the International Space Station.

NASA astronauts Sunita “Suni” Williams and Butch Wilmore are now one step closer to returning home from the ISS.

Powered by a Falcon 9 rocket, the spacecraft reached a speed of 17,500 mph as it headed into space after lifting off on Friday at 7:03 p.m. ET.

Docking at the ISS is scheduled for Saturday at 11:30 p.m. ET. They will open the hatch and enter the station at 1:05 a.m. ET on Sunday.

The launch was initially planned for Wednesday evening but postponed due to a problem with a ground support clamp arm on the Falcon 9 rocket. SpaceX subsequently said the hydraulic system issue was fixed and the crew was once again cleared for take-off on Friday.

Dragon is transporting the Crew-10 team made up of NASA astronaut Anne McClain, the mission’s commander; NASA astronaut Nichole Ayers, the mission pilot; Japan Aerospace Exploration Agency astronaut Takuya Onishi; and cosmonaut Kirill Peskov, with Roscosmo, Russia’s space agency.

Crew-10 will relieve four astronauts who are part of the current station crew, including Williams and Wilmore. The two astronauts planned to spend about a week on the ISS, but that brief stop turned into a nine-month mission when NASA determined that it was unsafe to bring them home on the Boeing Starliner spacecraft they rode into orbit.

The duo arrived at the ISS in early June, but in September, NASA opted to bring the Starliner back home empty due to concerns about technical issues with the craft. This mission marked Boeing’s first crewed flight of the Starliner. An empty Starliner landed safely back on Earth on Sept. 6.

The two American astronauts became part of the ISS Crew-9 team and have been actively engaged in research and maintenance of the station ever since. The extended time in space also allowed Williams to break the record for the most spacewalking time by a woman, with 62 hours and 6 minutes in the vacuum of space.

NASA has long insisted that Williams and Wilmore were never stuck or stranded.

In September, three months after the pair arrived at the ISS, a Roscosmos Soyuz spacecraft arrived at the station with two cosmonauts and an American astronaut. Several weeks later, American astronaut Nick Hague and cosmonaut Aleksandr Gorbunov arrived at the station onboard the SpaceX Crew Dragon Freedom spacecraft. Both vehicles have remained docked to the ISS and available for emergencies ever since.

The SpaceX Crew Dragon Freedom capsule that brought Hague and Gorbunov to the ISS is currently docked at the station will be the one that brings Williams, Wilmore and the two other Crew-9 astronauts back home. Endurance will remain docked at the station along with the Soyuz.

There is a period of overlap when the new team and the current crew of seven work collaboratively to ensure a smooth handover. NASA has said Williams and Wilmore could be home as soon as Wednesday.

NASA said that Crew-10 will conduct more than 200 scientific experiments and technology demonstrations during their mission to help humans eventually go deeper into space.