20thcentury africanamericanastronauts africanamericanengineers africanamericanleadership africanamericanmen africanamericans africanamericansintheprofessions biography communitylife discriminationinemployment economicconditions employment glassceiling(employmentdiscrimination) history intergenerationalrelations interviews officialsandemployees racediscrimination rolemodels rulesandpractice socialconditions socialvalues successfulpeople unitedstates