Guest: Dr. Vadim Rygalov, Assistant Professor of Space Studies at the University of North Dakota, returned for this program to discuss stress and emotional, physiological, psychological and radiological issues for long duration space missions. Dr. Rygalov began the discussion by summarizing the key issues facing those experiencing long duration space missions and he explained why most of the research focuses on short mission, which is defined as less than 3-5 months long. Do not miss this discussion. One listener asked Dr.