In space every environmental need for humans to survive—including air to breathe, water to drink, food to eat, and room to move around—must be provided by artificial methods. This means a fully contained life-support environment must exist, including everything from light and heat to air recycling and waste removal. Above Earth’s atmosphere, it is also essential for any human habitat in space to provide protection against hazards in the space environment, such as excessive radiation, cosmic rays, or meteoroids.