Washington (AFP)

Two American astronauts, en route to Earth aboard the SpaceX capsule, were preparing for a high-risk water landing in the Gulf of Mexico on Sunday after two months aboard the International Space Station (ISS).

"It's the big day, Bob Behnken and Doug Hurley return to Earth," tweeted NASA, which has not landed astronauts since 1975 and has been dependent for almost ten years on the Russians to transport them to the laboratory orbital.

A success of this mission would allow the United States to regain their spatial autonomy, while delegating to a private company the transport to the ISS to concentrate on other exploration missions, notably on the Moon or on Mars. .

The two men bade farewell to their three colleagues on the ISS, about 400 km from Earth, on Saturday and left the station without a hitch around 11:34 GMT.

The US space agency has decided to maintain their trip despite tropical storm Isaias, which brings strong winds and heavy rain to the east coast of Florida. However, it gave up on the first site envisaged, located on the more exposed Atlantic coast.

- Parachutes -

A few hours from the finish, SpaceX's Crew Dragon capsule, a company of eccentric entrepreneur Elon Musk, was traveling at more than 28,000 km / h.

At 13:51 (17:51 GMT), it will begin a series of delicate maneuvers, starting with the unloading of unnecessary equipment for the end of the trip. After being placed in the right trajectory, it will enter the atmosphere at 2:32 p.m. (6:32 p.m.). Its heat shield will have to withstand temperatures of the order of 1,900 degrees.

If all goes as planned, the first parachutes will deploy at an altitude of around 4.5 km to slow its fall and the main parachutes will open 1.8 km from Earth.

A NASA ship, GO Navigator, has been deployed to pick up the crew who will immediately undergo medical examinations before being brought back to land.

The Dragon Crew capsule will be transported to a SpaceX site in Florida for a six-week inspection to verify that it can again serve as a space taxi.

Last year, she completed this mission empty and without incident. If everything is repeated identically, SpaceX, which has been transporting cargo to the ISS since 2012, will be able to boast of being the first private company to provide the shuttle to the ISS for astronauts.

- Thomas Pesquet in 2021 -

On May 30, the company of Elon Musk, creator of PayPal or Tesla electric vehicles, had achieved a first feat by transporting Bob Behnken and Doug Hurley to the orbital laboratory.

It was the first manned flight launched from the United States since 2011, when the space shuttles were shut down. Americans have since been traveling on Russian rockets.

For three billion dollars, granted since 2011 as part of a fixed price contract, SpaceX has promised NASA six round trips to the ISS, with four astronauts on board.

The next mission, scheduled for the end of September, should transport three Americans, Michael Hopkins, Victor Glover, and Shannon Walker and a Japanese Soichi Noguchi, who will stay six months in space.

French astronaut Thomas Pesquet said this week that he will in turn travel aboard SpaceX's Crew Dragon for his second mission to the ISS in spring 2021.

© 2020 AFP