Aside from the earliest days of Mercury and Vostok, spaceflight has been a shared venture. In assembling a crew, it is necessary to consider how the qualities of different people interplay. Complementary needs, similar values and attitudes, and a strong but noncompetitive work orientation are among the qualities that are thought to contribute to social compatibility. Groups can be aided by the inclusion of individuals who are personally attractive, competent, and who can respond both to the demands of the task and to the needs of others. People who are similar to each other appear to have a compatibility advantage, at least in the short term, but bringing together individuals differing in age and social and cultural backgrounds, and of both sexes is likely to enrich the confinement experience over time.
Leadership is presumed to be a major factor in the effectiveness of spacecrews.
Autocratic decision making appears to have an advantage when expertise is concentrated in the hands of the leader and when speed in decision making is important. Democratic procedures can lead to better decisions when expertise is distributed across group members and when it is desirable for all to have a high degree of commitment to the decision. There are many ways in which spaceflight conditions are likely to affect dynamics within small groups. Historically, members of isolated and confined groups have had difficulty containing interpersonal conflict without resorting to social withdrawal. Direct training in interpersonal relations may be of some help in this regard.