article_snippet: NASA wants to know more about the impact of long-duration spaceflights on the human body to help plan missions to Mars and deeper into space.
article_snippet: Spending that much time in a weightless environment will take a toll.
article_snippet: NASA says space station astronauts have vision changes, bone loss, muscle atrophy and other problems.
article_snippet: NASA says the experiments should have benefits on Earth, such as helping patients recover from long periods of bed rest to improved monitoring of people whose bodies are unable to fight infections.
article_snippet: But astronauts and cosmonauts still report feeling isolated and confined at times.