The two NASA astronauts whose return to Earth was delayed for months are on their way home.

       Sunita "Suni" Williams and Barry "Butch" Wilmore left the International Space Station on a SpaceX Dragon spacecraft early on Tuesday and began an approximately 17-hour journey toward a splashdown off the Florida coast.

       NASA astronaut Nick Hague and cosmonaut Aleksandr Gorbunov were also onboard the craft as it undocked at about 1:05 a.m. ET.

       Williams and Wilmore had in June 2024 performed the first astronaut-crewed flight of Boeing's Starliner capsule. What was expected to be a weeklong trip to the ISS instead turned into a nine-month stay.

       Their return spacecraft early on Tuesday maneuvered in space, moving above and behind the station, before firing a series of departure burns that sent it back toward Earth.

       NASA said it expected the return trip to end at about 5:57 p.m., when the Dragon is scheduled to splash down off the Florida coast.

       This is a developing story. Please check back for updates.

       ABC News' Matthew Glasser and Mary Kekatos contributed to this report.