A four-person crew entered the International Space Station on Sunday|@Space_Station|X

NASA and SpaceX launched a four-person crew to the International Space Station (ISS) early Sunday, paving the way for astronauts Suni Williams and Butch Wilmore to return home after spending over nine months in space. 

Initially set for just over a week, their trip stretched unexpectedly due to technical failures in Boeing’s Starliner spacecraft.

NASA astronauts Anne McClain, Nichole Ayers, Japan’s Takuya Onishi, and Russian cosmonaut Kirill Peskov arrived at 1:35 a.m. ET.

Williams and Wilmore will probably depart the ISS later this week. Their unexpected extended stay began when Starliner, launched on June 5, suffered helium leaks and thruster malfunctions, forcing NASA to adjust mission plans. According to experts, the two will only receive their usual salary. They will not receive compensation or overtime for their extended stay.