According to Live Science report, the record of staying for the most days in space was made by Valeri Polyakov. He stayed in space for 437 days for 437 days from January 1994 to March 1995. However, he spent that time not on the ISS but at the Mir Space Station, which is now closed. Scientists wanted to study what affects the human health staying in space for a long time and Polyakov chose this mission on his own.
Talking about staying for the longest days at the International Space Station, Frank Rubio of America, Sergei Prokopayev and Dmitry Phetlin of Russia have been on ISS for 371 days. The three made this record from September 2022 to September 2023.
These astronauts were part of the same mission. The spacecraft with which the three had to return, a space got damaged by the debris. In such a situation, the three had to wait for 6 months on the ISS.
How many days Sunita Williams will stay on space
If Sunita Williams returns till February 2025, she will spend about 240 days in space. If she returned in March, she can stay in space 270 days. This means that Sunita and Buch will not be able to break the old records.