In anticipation of someday sending humans to Mars, NASA has begun searching for suitable locations for humans to land. The agency is looking for locations of high scientific value that would also provide resources to allow human explorers to land, live, and work on Mars. Locally derived natural resources such as water and oxygen are crucial for humans to explore Mars. (More about exploration zones.)
Liquid water could be potentially be extracted from ground ice (at or buried beneath the surface), the atmosphere or hydrated minerals. Oxygen can be generated from the carbon dioxide that makes up most of Mars' atmosphere. The Mars 2020 rover mission will include an instrument (MOXIE) to demonstrate the technology for oxygen generation.