Assertion: biosphere | /r/ObjectUse | used for its original intended purposes
Facets:
value: from 1991
type: TEMPORAL
value: as a closed-system experiment
type: PURPOSE
Source sentences:
text: Biosphere 2 was only used twice for its original intended purposes as a closed-system experiment: once from 1991 to 1993, and the second time from March to September 1994.