With future long duration exploration missions to the Moon, Mars and beyond, it will become imperative for the mission crew to have higher degrees of autonomy than today, due to long communication delays preventing mission control to provide immediate support in case of emergencies. To help address such issues, this paper describes the on-going development of a virtual assistant that would support the crew in the particular context of treating flight anomalies. Specifically, this paper describes the high-level requirements and system architecture of a virtual assistant to support the crew on tasks related to anomaly detection, diagnosis and resolution during long-duration human space exploration missions. The validation plan including a set of laboratory experiments and a validation campaign in the Human Exploration Research Analog (HERA) is also discussed. This project is part of the Human Capabilities Assessments for Autonomous Missions (HCAAM) Virtual NASA Science Center of Research (VNSCOR) within the NASA Human Research Program.