According to Nasa, the US record she set in April leaves her eighth on the Russian-dominated all-time space endurance list, just behind Yurchikhin who has now logged 673 days.

During the 57-year-old biochemist’s mission at the ISS she also broke the record for the longest ever space flight completed by a woman, eclipsing Italian astronaut Samantha Cristoforetti’s 199-day mission in June.

Watch: Peggy Whitson talks about the challenges of spacewalking

Jack “2Fish” Fischer, 43, went into space as a rookie but has won over space watchers with his boundless enthusiasm during his four-and-a-half months aboard the ISS.

He likened the feeling of his spacewalk with Whitson in May – the 200th ISS spacewalk – to a “ginormous fondue pot, bubbling over with piping hot awesomesauce.”

“Heading home soon ... I hope I infected a few of you with my passion for space. Never stop learning and growing. I dare you to dream!” he tweeted Friday.

The US pair’s expected return to the Johnson Space Centre in Houston has been complicated by the deadly floods and storms that have devastated Texas, however.

Nasa said Friday it was “reviewing” Whitson and Fischer’s return “as a result of the impacts of Hurricane Harvey”.

Historic rainfall in the region has wrought particular damage on built up Houston and Nasa confirmed that the Johnson Space Centre had seen “significant” damage in a Friday tweet.

Mission Control remains “operational” the agency said.

The ISS orbits the Earth at a height of about 400 kilometre, circling the planet every 90 minutes at a speed of about 28,000 kilometres per hour.