The conquest of space turns towards the preparation of long-duration manned flights (planetary exploration), even towards the establishment of permanent space bases (on the Moon or Mars for example), and requires man to ensure his survival thanks to closed systems, without exchange of matter with the outside world. It is then a question of reconstituting artificially in a reduced space, under controlled conditions and with very fast time constants, the cycle of matter as it exists on earth. Life support systems must perform different functions: food production, water recycling, air control...