Record-breaking US astronaut returns to Earth

Koch touched down at 0912 GMT on the Kazakh steppe after 328 days in space along with Luca Parmitano of the European Space Agency and Alexander Skvortsov of the Russian space agency.

Dmitry Rogozin, head of Russia's Roscosmos space agency, said the crew had returned safely.

"All is well on board, the crew are feeling well," Rogozin wrote on Twitter.

Koch, a 41-year-old Michigan-born engineer, beat the previous record for a single spaceflight by a woman -- 289 days, held by NASA veteran Peggy Whitson -- on December 28, 2019.

She had already made history by that point as one half of the first-ever all-woman spacewalk along with NASA counterpart Jessica Meir in October.

Koch told NBC on Tuesday that she would "miss microgravity" as she spoke to journalists ahead of the three-and-a-half hour journey back to Earth.

"It's really fun to be in a place where you can just bounce around between the ceiling and the floor whenever you want," she said, smiling as she twisted her body around the ISS.

Koch called three-time flyer Whitson "a heroine of mine" and a "mentor" in the space programme after she surpassed the 59-year-old's record.

She also spoke of her desire to "inspire the next generation of explorers".

Koch's return comes after an advert produced by the skincare brand Olay ran during an intermission in the American football Super Bowl with a call to "make space for women".

The advert featured NASA astronaut Nicole Stott and saw the company promise to donate up to $500,000 to the non-profit Women Who Code, which works with young women seeking careers in tech and scientific fields.

This year's Super Bowl was watched by over 100 million people while advert time costs more than USD 5 million for a 30-second commercial.

The first woman in space was Soviet cosmonaut Valentina Tereshkova whose spaceflight in 1963 is still the only solo mission carried out by a woman.

But the cosmonauts Russia has sent to the ISS since expeditions began in 2000 have all been men with the exception of Yelena Serova's launch in 2014.

Both Tereshkova and Serova are now lawmakers in the Russian parliament, where they represent the ruling United Russia party.

Unlike Koch, whose stay aboard the ISS was extended, Parmitano and Skvortsov are rounding off regular six-month missions.

Parmitano handed over command of the ISS to Roscosmos' Oleg Skripochka on Tuesday.

The 43-year-old Italian posted regular shots of the Earth while aboard, highlighting the plight of the Amazon rainforest and  describing the Alps as "like a spinal column, never bending to time".

Four male cosmonauts have spent a year or longer in space as part of a single mission with Valery Polyakov's 437 days the overall record.

Scott Kelly holds the record for a NASA astronaut, posting 340 days at the ISS before he returned home in 2016.