Closed ecological system in the context of Ecosystems

The biosphere (from Ancient Greek βίος (bíos) 'life' and σφαῖρα (sphaîra) 'sphere'), also called the ecosphere (from Ancient Greek οἶκος (oîkos) 'settlement, house' and σφαῖρα (sphaîra) 'sphere'), is the worldwide sum of all ecosystems. It can also be termed the zone of life on the Earth. The biosphere (which is technically a spherical shell) is virtually a closed system with regard to matter, with minimal inputs and outputs. Regarding energy, it is an open system, with photosynthesis capturing solar energy at a rate of around 100 terawatts. By the most general biophysiological definition, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, cryosphere, hydrosphere, and atmosphere. The biosphere is postulated to have evolved, beginning with a process of biopoiesis (life created naturally from non-living matter, such as simple organic compounds) or biogenesis (life created from living matter), at least some 3.5 billion years ago.

In a general sense, biospheres are any closed, self-regulating systems containing ecosystems. This includes artificial biospheres such as Biosphere 2 and BIOS-3, and potentially ones on other planets or moons.

An ecosphere is a planetary contained ecological system. In this global ecosystem, the various forms of energy and matter that constitute a given planet interact on a continual basis. The forces of the four Fundamental interactions cause the various forms of matter to settle into identifiable layers. These layers are referred to as component spheres with the type and extent of each component sphere varying significantly from one particular ecosphere to another. Component spheres that represent a significant portion of an ecosphere are referred to as a primary component spheres. For instance, Earth's ecosphere consists of five primary component spheres which are the Geosphere, Hydrosphere, Biosphere, Atmosphere, and Magnetosphere.

University of Arizona Biosphere 2 is an American Earth system science research facility located in Oracle, Arizona. Its mission is to serve as a center for research, outreach, teaching, and lifelong learning about Earth, its living systems, and its place in the universe. It is a 3.14-acre (1.27-hectare) structure originally built to be an artificial, materially closed ecological system, or vivarium. It remains the largest closed ecological system ever created. Constructed between 1987 and 1991, Biosphere 2 was planned to experiment with the viability of closed ecological systems to support and maintain human life in outer space as a substitute for Earth's biosphere.

It was designed to explore the web of interactions within life systems in a structure with different areas based on various biological biomes. In addition to the several biomes and living quarters for people, there was an agricultural area and work space to study the interactions between humans, farming, technology and the rest of nature as a new kind of laboratory for the study of the global ecology. Its mission was a two-year closure experiment with a crew of eight humans. Long-term it was seen as a precursor to gaining knowledge about the use of closed biospheres in space colonization. As an experimental ecological facility it allowed the study and manipulation of a mini biospheric system.

BIOS-3 is an experimental closed ecosystem at the Institute of Biophysics in Krasnoyarsk, Russia.

Its construction began in 1965, and was completed in 1972. BIOS-3 consists of a 315 cubic metres (11,100 cu ft) underground steel structure suitable for up to three persons, and was initially used for developing closed ecological human life-support ecosystems. It was divided into 4 compartments, one of which is a crew area. The crew area consists of 3 single-cabins, a galley, lavatory and control room. Initially one other compartment was an algal cultivator, and the other two phytotrons for growing wheat or vegetables. The plants growing in the two phytotrons contributed approximately 25% of the air filtering in the compound. Later, the algal cultivator was converted into a third phytotron. A level of light comparable to sunlight was supplied in each of the 4 compartments by 20 kW xenon lamps, cooled by water jackets. The facility used 400 kW of electricity, supplied by a nearby hydroelectric power station.

A space settlement (also called a space habitat, spacestead, space city or space colony) is a settlement in outer space, sustaining more extensively habitation facilities in space than a general space station or spacecraft. Possibly including closed ecological systems, its particular purpose is permanent habitation.

No space settlement has been constructed yet, but many design concepts, with varying degrees of realism, have been introduced in science-fiction or proposed for actual realization.