Scientists: "Hey, let's send people to Mars and never bring them back." Obama Administration: "No, let's bring them back."

Naturally, these considerations are being driven by the only thing that matters in space exploration...$$$$$$.    Personally, I wouldn't mind sending astronauts on a one-way trip to Mars, provided they were 1) willing to go, 2) informed of the potential consequences (i.e. early death) and 3) were somewhat elderly to begin with. 

To be honest, "one-wayers" will be needed eventually to establish a base, which in turn can lay the groundwork for a sustainable colony.   Constantly ferrying people back and forth between Mars and Earth I'm sure would increase the cost of a Mars colony by two orders of magnitude.  You can read about it in the link below.

http://www.rawstory.com/rs/2010/11/scientists-propose-oneway-trips-mars/