With the recent exploration of probes to Mars, a lot of hype has been drawn on manned missions to Mars. The possibility of life existing at some point in time is almost certain as existence of the planet being warm and wet, with lakes, rivers, active volcanoes, and a thick atmosphere. With Mars being Earth's sister planet, the possibility of human kind being able to live within the atmosphere that gives protection against meteorites and radiation is quite dominant. But, along with everything else, comes the price tag of human exploration to the planet.
The mission to Mars will come with a price of more than $400 million, mainly because of the distance to the planet. The possibility of using the moon as a launch to Mars greatly reduces the price due to lower gravity, but the return trip is almost unheard of by many scientists due to lack of fuel needed to return home to earth. So if we can't make it back Mars, why not just make the trip a one-way trip to planet. The probability is being talked among many who believe that Mars could be an adaptive place for initial colony of four astronauts to live. Equipped with a small nuclear reactor, a couple of rover vehicles, the few could make their own oxygen and food to survive on the planet. Obviously this might not be that simple due to constraints on possibilities of things going wrong. With so many different situations that could go wrong, you can imagine many astronauts are not jumping up to take on the mission.
Along with all the risks that one might encounter, many factors would fear into picking a crew for this exploration. The age and maturity of one, along with weight, scientific credentials, are critical when picking the astronaut. Also the person has to factor in whether or not the person is willing to possibly die for a mission that almost seems improbable.
The pros of this mission are far and long to factor in. Having the possibility of human existence past the boundaries of Earth has been a long thought of thing that many seem to only dream about.