Because the planet is now 171 million miles away, it took 15 minutes at the speed of light for the first faint radio signal of success to reach the scientists, relayed from Mars Odyssey, the orbiter flying high above the landing site. Carl Sagan famously announced that existing technology could place humans on the red planet, but the great distance involved precluded the possibility of an immediate return journey. Robert does make an interesting case that life can not only be supported on Mars, but will actually flourish. Which creates an interesting question: would you sacrifice yourself, on a one-way trip, to establish a human presence on Mars?
Let's consider the more prosaic reasons for colonizing Mars: similarity to Earth, economic value, inter-planetary position for further exploration, scientific discoveries etc. The best reason has to be the focus it will provide to Earthbound humans though. Here's a concept that transcends narrow national interests, in fact in can only be realized through tremendous vision and cooperation. To make it happen all current disputes and conflicts will have to cease. Imagine that, an idea so big it can relegate any problem we have to the backseat. The idealism it will unlock can unify our species to a common goal, greater than any we have imagined in our history.