We can't go to outer space to test equipment and procedures, so scientists find places on Earth that most resemble outer space.
Researchers use many places such as deserts, valleys, and frozen lakes to work and collect data.
NASA's Earth Analogs program uses many places in preparation for astronaunts to travel to Mars.
Devon Island in Canada is the largest uninhabited island on Earth.
On this island, scientists do experiments so they can predict how things will behave in a Martian atmosphere.
Although it is not the same experience as going to Mars, this Arctic Island is the closest we can find on Earth.