unifying the work of research centers from North America, Central America and Canada. It currently has 180 member stations. Another biological non-profit is the Organization for Tropical Studies which was founded in 1963 and consists of approximately 50 institutions worldwide. Its three goals consist of 1) furthering scientific discovery and knowledge, 2) expanding the educational scope of tropical natural resources and 3) helping to shape policies that will impact these regions. It provides both undergraduate and graduate programs to students in the fields of field biology, ecology, global health, and conservation and allows students to perform hands-on work in both African and South American continents. There are also numerous other organizations and institutes, both public and private, around the world that support the funding, approval and maintenance of biological research stations. Space stations Space stations are not stationary buildings unlike normal research stations on Earth, they are specially created mobile spacecraft that are built to allow a group of human researchers and crew to inhabit over a span of anywhere from months and even a year. Space stations are intended to be permanently operating in space unlike other kinds of space craft such as satellites. However, it may not be permanently inhabited by human researchers who may come and go as they cycle through different explorations. Space stations are typically controlled by their own respective space agency and country. The design for space stations evolved over multiple decades. The engineering and design aspects of a space station was first introduced by Herman Potocnik in 1928. His "Wohnrad" also known as "Living Wheel" consisted of a rotating wheel-shaped space station consisting of three parts: a habitat rotation wheel, an observatory, and a machine room. The Wohnrad's habitat wheel consisted of habitation units, laboratories and observatories which would measure 30 meters in diameter and whose centrifugal force would generate a sense of gravity for the crew members. The theme of gravity being artificially produced through the rotation of the space station was first detailed by Wernher Von Braun in the 1950s which maintained a similar concept of a rotating wheel. The International Space Station (ISS) is one of the biggest space stations in the world and it is permanently inhabited. The first parts of the stations were launched in 1998. It operates in a low Earth orbit which means that relatively closer to the Earth's surface. This can be anywhere from 1000