It seems like only science fiction has ever been able to put people on a planet to live in a controlled environment for extended periods of time, but scientists and astronomers really want to accomplish this in real life too, for say, one year or so.
With this desire come challenges; Mars isn't exactly very human-friendly, and as a result, humans would have to live in a pressurized man-man enclosure and wouldn't be able to leave their space suits when leaving the enclosure to explore.
Mars lacks a decent supply of oxygen, and instead, the atmosphere is almost 96% carbon dioxide. The atmospheric conditions also make it difficult to protect potential astronauts from radiation, and effects from distant light without an atmosphere to protect them has been known to cause eye problems for astronauts. Among other things, a body tuned to Earth's gravity can experience odd side-effects in a different gravitational environment, such as problems with sleep, blood pressure, muscles, and more.
Mars isn't overly distant from Earth, but it does take a while to get there. Because Mars is not as close to the Earth as the Moon or the International Space Station are, it can take up to nine months to get an astronaut to Mars. Then, adding in the time they'd spend staying there, and the time to get back, we're looking at close to two years or more away from home.
If astronauts were to go to Mars, they'd need a food supply that would last them, and they would have to rely on constant food supply refreshes, as well as an oxygen system, which would be difficult to achieve because of the distance. Supplying the International Space Station, for example, is much easier because it orbits the Earth and is significantly closer than Mars is.
Will it happen? - Maybe some day, but not with current technology.
