NASA astronauts riding SpaceX capsule poised for Sunday return

The two NASA astronauts who rode to the International Space Station aboard SpaceX's new Crew Dragon are heading home for a Sunday splashdown in the Gulf of Mexico.

Crew Dragon "Endeavor" decoupled from the orbital station at 7:35 pm ET carrying US astronauts Bob Behnken and Doug Hurley ahead of a Sunday afternoon splashdown off the coast of Pensacola, Florida.

"It's been a great two months, and we appreciate all you've done as a crew to help us prove out Dragon on its maiden flight," Hurley told the remaining US station crew member Chris Cassidy, as Crew Dragon autonomously eased away from its docking port to begin the 21-hour journey home.

NASA and SpaceX — monitoring the crew's return from Houston, Texas and SpaceX's headquarters in Hawthorne, California — ruled out splashdown options in the Atlantic earlier this week due to Tropical Storm Isaias.

Upon a successful splashdown at 2:48 pm ET Sunday, the spacecraft will have completed its final key test to prove it can transport astronauts to and from space.

"The hardest part was getting us launched, but the most important part is bringing us home," Behnken said during a farewell ceremony early on Saturday aboard the space station.

NASA officials have said Crew Dragon has been in a "very healthy" condition since docking to the space station, where astronauts have been conducting tests and monitoring how the spacecraft performs over time in space.

Behnken and Hurley will have a few hours for sleep during their journey home in the capsule, which will gradually decrease its orbital altitude through a series of automated thruster firings.

"They've got plenty of food and water aboard the spacecraft," SpaceX engineer Siva Bharadvaj said during a livestream of the undocking.