During their time in space, their bodies have adapted to the microgravity environment, and their muscles and bones have weakened due to lack of use. This can make it difficult for them to adjust to the stronger gravitational pull of Earth after their mission. It typically takes several days or even weeks for astronauts to fully readjust to Earth’s gravity and regain their normal physical abilities. More information: 3 reasons why astronauts can’t walk after landing on earth