I think going to Mars would be a very good thing and something we should seriously look into soon. A journey to Mars would be too big for one nation, as such it would encompass nations from all over the globe, and I think everyone working on a project for each other, towards a common goal might help bring people together and might take their minds off the fact that we all want o kill one another.
But then again....... I do watch alot of Star Trek....
subnote- just realised that Izipo has just said pretty much exactly what I have, but I've left my comments in to show my agreement heh
And He said something I missed, it would help speed development in other fields. And to the best of my knowledge there are two things which help speed up development and that's exploration and war, I think the former is a better choice.
One thing I do want to add. People say we shouldn't go because 11,000,000 children are dying and the like, but the thing is, I get the impression from the news and what not that the governments aren't doing a HUGE deal about that, it comes down to people such as Mr Gates and Sir Tom Hunter to give money to help that whilst countries like America and Russia would much rather spend money on new fighter jets or more powerful non-nuclear bombs. So I think perhaps taking money away from areas like that and putting it towards space exploration and potential new areas of research would look alot better in the eyes of the world governments than helping others.