Astronauts set to return after marathon 196-day ISS mission

French astronaut Thomas Pesquet is due to return to Earth on Friday (June 2) after a marathon 196-day trip that will fall just shy of a record space mission for a European.

The world was a different place when Pesquet, Russia's Oleg Novitskiy and American Peggy Whitson arrived on the International Space Station (ISS) on November 20 for a six-month mission.

Since then, Donald Trump has replaced Barack Obama in the White House and a young centrist, Emmanuel Macron, has taken over from Francois Hollande as president in Pesquet's native France.

Pesquet, 39, and Novitskiy, 45, are due to quit the ISS on Friday morning for a Soyuz MS-03 spacecraft which will transport them back to the steppes of Kazakhstan. Whitson will remain on the ISS until September.

The 400-kilometre (250-mile) descent is expected to take around three hours and 20 minutes, with touchdown scheduled for 1430 GMT.

Along the way, their Soyuz will separate into three parts, leaving the orbital and propulsion modules to burn up as they fall to Earth.

The descent module will encounter temperatures of up to 1,600 degrees Celsius (2,900 degrees Fahrenheit) as friction from the atmosphere heats its protective shield.

"The two astronauts have accomplished all the tasks that were given to them in a satisfactory manner," said Yuri Malenchenko, the number two at the cosmonaut training centre outside Moscow.

"Thomas Pesquet... is a real professional with a great desire to work in space. And this flight has confirmed these qualities," Malenchenko said.

"Thomas has worked in a remarkable fashion," Jean-Yves Le Gall, the head of CNES, France's space agency, told AFP.

The record for the longest continuous mission in space by a European is held by Italian Samantha Cristoforetti, who was in orbit for 199 days from November 2014 to June 2015. She also broke the record for the longest single mission for a woman.

But that is far short of the 437-day mission by Russian cosmonaut Valery Polyakov, aboard the old Soviet-Russian space station Mir, from January 1994 to March 1995.

Pesquet underlined the fragility of Earth in an interview to AFP from the ISS.

"There are things that one understands intellectually, but which one doesn't really get," the 39-year-old said via video link, gently floating around in the zero gravity of space.

When it comes to global warming, "we talk of two degrees (Celsius) or four degrees -- these are numbers which sometimes exceed human understanding.

"But to see the planet as a whole... to see it for yourself... this allows you to truly appreciate the fragility."

Pesquet is France's 10th ISS astronaut and has become a bit of a social media celebrity at home, with more than 550,000 followers on Twitter where he frequently posted photographs of Earth from space.