Abstract
The limit of population on earth has been considered as about 30 billions depending on the ecological capacity of earth itself. According to the recent report of United State, world-wide population would reach to 5 billions in this July and continue to increase at rate of doubling every 40 years. The destruction of the global ecological balance based on population increase and the expansion of social and economic activities of human beings is now going to become the problems to be solved programatically in the international cooperation frame work. The world-wide trends of space activities are also going to expand the general human activities on earth to the human activities in space, namely in space infrastructure in order to expand the human activities in space, long duration stays of human beings in space become essential and new self-contained life support system called Controlled Ecological Life Support System (CELSS) is to be developed. The research and development of new artificial biosphere -CELSS - would also take an important role for the conservation of earth environment in future. This paper describes the purpose and present status of CELSS development and the key for CELSS.
