Fictional universe of Avatar
In the 2009 science-fiction film Avatar, director James Cameron conceived a fictional universe in which humans seek to mine unobtanium on the fictional habitable exomoon Pandora. The Earth-like moon is inhabited by a sapient indigenous humanoid species called the Na'vi, as well as varied fauna and flora. Resources Development Administration (RDA―which, despite the name, is a public company which evolved from a Silicon Valley startup) scientists, administrators, recruits, support, and security personnel travel to Pandora in the 22nd century to discover this beautiful, lush world, which is inhabited by many lifeforms including the human-like Na'vi. The clan with which the humans have contact in the film lives "in a giant tree that sits on a vast store of a mineral called unobtainium, which humans want as an energy supply."[1]
The Na'vi are humanoid creatures that inhabit Pandora along with other creatures. They use animals ranging from direhorses to even viperwolves.
The Pandoran biosphere teems with a biodiversity of bioluminescent species ranging from six-legged animals to other types of exotic fauna and flora. The Pandoran ecology forms a vast biological neural network spanning the entire lunar surface into which the Na'vi and other creatures can connect. The strength of this collective consciousness is powerfully illustrated when the human invaders are defeated in battle by the Pandora ecology after the resolute Na'vi were nearly defeated. Cameron used a team of expert advisors in order to make the various examples of fauna and flora as scientifically feasible as possible.[2]
In the film, Pandora is depicted as being located in the Alpha Centauri A system, about 4.37 light-years (276,000 AU) from Earth. It is one of the many natural satellites orbiting the gas giant Polyphemus,[3] named for the Polyphemus of Greek mythology. Pandora's atmosphere is a mix of nitrogen, oxygen, carbon dioxide, xenon, methane, ammonia and hydrogen sulfide, the latter three of which are unbreathable for humans, who wear Exo-Packs when outside their buildings or vehicles. The atmosphere of Pandora does have enough oxygen for humans (21%-22%), but too much carbon dioxide (16%-18%). The Na'vi have special organs (similar to kidneys) called Wichow that take advantage of this atmosphere to extract greater amounts of oxygen for their bloodstream. These organs use carbon dioxide and water in their bodies and convert them into methane and oxygen. The methane is exhaled back into the atmosphere. The extra oxygen is added to the Na'vi bloodstream to help power their extra-large bodies and powerful muscles. This process accounts for the small amount of methane in the Pandoran atmosphere. At rest or when the Na'vi are dormant,those same organs can convert some small amounts of methane back into carbon dioxide and water to replenish their water supply if needed. This is why humans can survive with just a filtration system (Exo-Packs), but the Navi need higher amounts of carbon dioxide to function. The high level of carbon dioxide and other gases such as hydrogen sulfide also help keep the Na'vi bloodstream a slightly acidic pH around 5.25-5.75 (humans 7.35-7.45).
Leri Greer, a designer at Weta Workshop, explained the unusual day/night cycle experienced by the Na'vi, who inhabit a moon orbiting a planet, that in turn orbits around a star.
