Many films and science-fiction books have shown colonies of humans living on the Moon or Mars, but at this time it is still a distant possibility. Since the 1960s, NASA has been planning lunar bases to use for scientific study or for training astronauts to go to Mars. Space stations have been designed to keep astronauts as comfortable as possible, with a 70 degrees Fahrenheit (21 degrees Celsius) constant temperature and all of the freeze-dried food, exercise equipment, and other amenities necessary for short-term life in space. However, only some people can actually adapt to a life in space, which includes a weightless environment, living in close quarters, and using technology necessary for carrying out routine daily activities. While it is possible for a scientific community to be functioning in space by the year 2020, it is less likely that the average citizen will be able to permanently relocate there anytime soon.