What challenges do astronauts face during long-duration space missions?

Living in space for months is hard. Astronauts face both physical and mental challenges. Without gravity, their muscles and bones become weaker, so they must exercise daily. They can also lose some sense of balance when they return to Earth. Space radiation is another risk that can affect their health. Mentally, being away from family and friends can cause stress and loneliness. Astronauts also live in small spaces with limited privacy. They have to work together and stay positive. Sleep schedules can be difficult because the Sun rises and sets many times a day in orbit.