NASA is seeking candidates to go into isolation for eight months in an experiment to help prepare for long-term stays on the moon and Mars. Researchers say results of the study will help them better understand the physical and mental effects on humans spending extended periods in space. The experiment is part of NASA’s Human Research Program. The program seeks to discover and develop “the best methods and technologies to support safe, productive human space travel.” Until now, American astronauts have only spent long space stays on the International Space Station - ISS. Most of these missions lasted several months, with the longest reaching nearly a year.