Similar to the Mission Commander, the hopeful Deputy Mission Commander submits an application at the end of the school year. This application is read and evaluated by the current Mission Commander and the Admiral. The selected Deputy Mission Commander is announced at the end-of-year barbeque. There is usually some ceremony involved in the announcement, involving the passing on of Office keys, the Sub-Commander Pin, and the Sub-Commander relic (the nature of which is classified).
Prior to the mission, the Deputy Mission Commander's duties consist of helping the Mission Commander with their duties. This help may include writing, reading, and evaluating the Astronaut Applications, planning the mission (including meal schedules, shift schedules, experiments, navigation data, and any other paperwork), and ensuring that the Habitat is properly prepared for the mission. During the mission, the Deputy Mission Commander is second in command of the Habitat, and will assume full command should the Mission Commander be rendered unfit for duty.