In order to increase their understanding of earth’s life - support systems, scientists experimented in the 1990 ’ s with a fully enclosed life - support system in Arizona, U.S.A.
Selleks et õppida paremini tundma elu alalhoiusüsteeme, eksperimenteerisid teadlased 1990. aastatel USAs Arizonas elu alalhoidva, täielikult suletud süsteemiga.