I like the idea of leaving the worse of ourselves behind as we reach for the stars. A new beginning with all of the good and as little as the bad as possible. The closest mankind got to a new beginning was when Christopher Columbus invaded the Americas but I don't consider this a good new beginning as there was no thinking behind it.
That event eventually lead to the formation of the United States of America which is mankind's best attempt at creating the perfect form of Government yet. It's not perfect because we're not perfect but it still revolutionized the world. Sadly, this form of Government can only be maintained for as long as the people within it are educated, and engaged, enough to keep it from collapsing and it does look, at least to me, like cracks are starting to show... but that's outside of the scope of this post.
It's not to say that everything is wrong with the world today or that we would get it right simply by starting over again but if we were to start a new civilization somewhere else it would force us to sit down and think about the type of society that we want to build. Having this moment to ponder about our new beginning would, hopefully, be as beneficial as it was in the creation of the United States of America.