Brazilian research station run by Horizon Corporation. The Ark is a self-contained biosphere, an airtight collection of buildings used to conduct experiments in how environments regulate themselves. The carefully balanced mix of plants and animals within the Ark is designed to mimic Earth's ecosystem. Air, water, and waste products are all recycled, allowing humans to live indefinitely inside the compound with no contact with the external world- in theory. The knowledge gained from research in self-contained biospheres such as the Ark could led to better life support systems for astronauts, as well as a greater understanding of how natural environments work.

The Horizon Ark was formally dedicated in July 1999. It was built under the auspices of the U.S. government's Rainforest 2000 Project. Horizon Corporation has announced that after an initial testing period experiments will begin in the fall of 2000.