The good people at Imperial College London have come up with a concept for a mission to send astronauts to Mars (and bring them back).
The idea is to spark debate about the technical aspects of such a mission. According to Professor Tom Pike, the team leader,
Every part of this mission scenario has been demonstrated one way or the other, including the in situ propellant production on the surface of Mars.
There are big, big jumps between a demonstration at one level and putting together the engineering systems for a mission, but they are engineering challenges. They are not fundamentally about making new discoveries.
Give the whole BBC article a read here.