The first astronauts launched by Elon Musk’s SpaceX company left the International Space Station on Saturday night for the last and most important part of their test flight to return home.
Nasa’s Doug Hurley and Bob Behnken bade farewell to the three men left behind as their SpaceX Dragon capsule was undocked for its Sunday afternoon descent by parachute into the Gulf of Mexico.
Despite the surge of Tropical Storm Isaias towards Florida’s Atlantic shore, Nasa said the weather off the Pensacola coast looked favourable.
It will be the first splashdown for astronauts in 45 years, after the joint US-Soviet mission in 1975 known as Apollo-Soyuz.
The astronauts’ homecoming will cap a two-month mission that ended a prolonged launch drought in the US, which has relied on Russian rockets to ferry astronauts to the space station since the end of the shuttle era.
In launching the men from Nasa’s Kennedy Space Centre on May 30, SpaceX became the first private company to send people into orbit. It will now be the first to bring them back.
“The hardest part was getting us launched, but the most important is bringing us home,” Mr Behnken said several hours before being strapped into the Dragon.
A successful splashdown, Mr Behnken said, would bring US-crew launching capability full circle.
At a farewell ceremony earlier in the day, space station commander Chris Cassidy, who will remain on board with two Russians until October, presented Mr Hurley with the small US flag left behind by the previous astronauts to reach the ISS from American soil.
Mr Hurley was the pilot of that shuttle mission in July 2011.
The flag – which also flew on the first shuttle flight, in 1981 – became a prize for the company that launched astronauts first.
The next SpaceX crew flight is planned for late September.