Space Exploration: Time and Priorities

This debate can be found at Live Journal's Space Exploration Community:
http://www.livejournal.com/community/spacexploration/211262.html?view=867134#t867134
Question:

I’m starting on an expository essay and the topic I've chosen is on whether or not we should be spending what we have been on space exploration (which I’m all for it). But I'm a little lost on how to start, besides solving the overpopulation problem by colonizing other planets, what other importance is there in space exploration?

My reply:

Our generation doesn't have to worry too much about overpopulation or the extinction of vital resources but our children and grand-children could be much more concerned.

I don't think the "colonization" of our solar systems is a priority given the costs of sending humans to space.

Getting knowledgeable about the solar system should be a priority given the benefits for basic science, technology, the environment. Robotic exploration is fine.

There is also the philosophical implications of finding life elsewhere than on Earth.

The robotic Exploration of Mars, Europa and Titan is a priority.

Developing new technologies for sending humans into space will become a priority when we will get enough evidence of Earth-like planets in other solar systems. Within one or two centuries, the Earth could become too small for the world population, then there will be the necessity of finding other places with the right atmosphere, the right resources and the right climate. When will it happen?

Sailom