The discovery of Gliese 581c with the conjecture there may be liquid water seems to occur relatively early on in the search for extrasolar planets. It would seem to indicate there may be quite a few of them out there, and some may support life as we know it.

What would eventually drive exploration of planets light-years away would be scientific curiosity. What would drive it faster is the possibility of colonization as this Earth becomes more and more stressed. There does not seem to be a dynamic to match the depradations of consumption and population expansion.

Now, let's assume that there were a planet which would support human life without much modification. (Ignore the fact that getting and keeping this planet to which we've evolved liveable would be the most cost-effective measure.) We have sent off a robotic mission which has reported that there is life something like us on Galactica 3, and running water, ice, and flora which could be a source of food and heat.

Obviously a habitable planet, as opposed to this Earth, which is increasingly uninhabitable.

How kind and considerate do you think Human Beings would be to the natives of Galactica 3? After all, we have the technology to get there, and God is on our side. And we need the room, having fouled our own nest.

It might be a great idea to NOT advertise our presence in the Universe. Anyone who could get here probably wouldn't regard us as particularly worthy beings, certainly not blessed by their particular God.

Arf