While no life has yet been discovered on Mars, humans have long considered the possibility of someday living on the Red Planet. The problem with this idea is that Mars experiences extreme conditions that would make it impossible for humans to survive. Two of the most extreme conditions are very low temperatures and high levels of radiation from the sun. Both of these make Mars currently unlivable for humans, plants and other forms of life. Yet discussions continue about sending people to Mars, with some even proposing a human colonization of the planet in the future. The American space agency NASA has plans to someday put humans on Mars. NASA’s goal is to first return humans to the Moon by 2024. The agency then plans to carry out several Moon missions in preparation for sending astronauts to Mars by the 2030s.