Desirable age mixes need to be better understood. In addition, we need to know more about adult development under spaceflight conditions. It is expected that social change coupled with a growing likelihood of international missions will increase cultural heterogeneity within spacecrews. The intergroup relations literature specifies certain conditions which are likely to reduce prejudice, and many of these conditions can be established in space. In addition to prejudice, problems include language or communication difficulties and differing, culturally related preferences regarding food, facilities, and activities.
Further research is a prerequisite for achieving coordination within ethnically mixed crews.
One such quality is personal attractiveness. It should prove useful to select-out individuals with characteristics that most other crewmembers will find aversive and individuals who find too many human qualities aversive. Second, emotional stability is very important. Perceived emotional stability may be as important as actual emotional stability, so it is necessary to study the psychological processes upon which judgments of emotional stability rest. Third, a high level of technical competence is crucial, especially for leaders.