Controlled ecological life-support system  Controlled (or closed) ecological life-support systems (acronym CELSS) are a self-supporting life support system for space stations and colonies typically through controlled closed ecological systems, such as the BioHome, BIOS-3, Biosphere 2, Mars Desert Research Station, and Yuegong-1. CELSS was first pioneered by the Soviet Union during the famed "Space Race" in the 1950s–60s. Originated by Konstantin Tsiolkovsky and furthered by V.I. Vernadsky, the first forays into this science were the use of closed, unmanned ecosystems, expanding into the research facility known as the BIOS-3. Then in 1965, manned experiments began in the BIOS-3. Space travel, thus far, has been limited to our own Earth–Moon system. Also, everything that astronauts would need in the way of life support (air, water, and food) has been brought with them. This may be economical for short missions of spacecraft, but it is not the most viable solution when dealing with the life support systems of a long-term craft (such as a generation ship) or a settlement. The aim of CELSS is to create a regenerative environment that can support and maintain human life via agricultural means. In non-CELSS environments, air replenishment and CO2 processing typically consists of stored air tanks and CO2 scrubbers. The drawback to this method lies in the fact that upon depletion the tanks would have to be refilled; the scrubbers would also require replacement after they become ineffective. There is also the issue of processing toxic fumes, which come from the synthetic materials used in the construction of habitats. Therefore, the issue of how air quality is maintained requires attention; in experiments, it was found that the plants also removed volatile organic compounds offgassed by synthetic materials used thus far to build and maintain all man-made habitats. In CELSS, air is initially supplied by external supply, but is maintained by the use of foliage plants, which create oxygen in photosynthesis (aided by the waste-byproduct of human respiration, CO2). Eventually, the main goal of a CELSS environment is to have foliage plants take over the complete and total production of oxygen needs; this would make the system a "closed", instead of "controlled", system. As with all present forays into space, crews have had to store all consumables they require prior to launch.