 Four NASA volunteers exited their ground-based home Saturday after a year-long mission where they lived in a simulated Mars environment here on Earth. Flight engineer Ross Brockwell, who took part in the study, says he's very grateful to have had this incredible opportunity to live for a year within the spirit of planetary adventure towards an exciting future. The crew took Mars walks, grew harvested several vegetables and maintained equipment and habitat. Two additional missions are planned for 2025 and 2027.