Russian space researchers will lock six men in a metal tube for more than year in an effort to mimic the stresses and challenges of a manned mission to Mars. The 500 Days experiment, under development by the Russian Institute of Medical and Biological Problems, will isolate human volunteers in a mock space station module for — as its namesake suggests — a complete 500 days to study how a long mission to Mars might affect its human crew. “Obviously, we’re very interested in the results,” NASA spokeswoman Dolores Beasley said of the long-duration study during a telephone interview. “It is a high priority for us.”