PENSACOLA - The first astronauts launched by Elon Musk’s SpaceX company departed the International Space Station on Saturday night for the final and most important part of their test flight: returning to Earth with a rare splashdown.

NASA’s Doug Hurley and Bob Behnken bid farewell to the three men left behind as their SpaceX Dragon capsule undocked. It's headed toward a Sunday afternoon descent by parachute into the Gulf of Mexico at 1:48 pm Central time.

Despite Tropical Storm Isaias’ surge toward Florida’s Atlantic shore, NASA said the weather looked favorable off the coast of Pensacola on the extreme opposite side of the state.

It will be the first splashdown for astronauts in 45 years. The last time was following the joint U.S.-Soviet mission in 1975 known as Apollo-Soyuz.

Space station commander Chris Cassidy rang the ship’s bell as Dragon pulled away, 267 miles above South Africa. Within a few minutes, all that could be seen of the capsule was a pair of flashing lights against the black void of space.

The astronauts’ homecoming will cap a mission that ended a prolonged launch drought in the U.S., which has relied on Russian rockets to ferry astronauts to the space station since the end of the shuttle era.