Traveling to the moon is so last century. Mars is small dusty ball with little of interest. The rest of the Solar System is either very, very hot or very, very cold. Where is an enterprising space traveler to set his sights? The stars, of course. Interstellar travel is widely considered to be impossible, or at the very least prohibitively difficult. That hasn't stopped a group of scientists, engineers and dreamers from forming the Tau Zero Foundation, whose purpose is to lay the groundwork for practical starflight.
I'm all for that. The group is in its infancy, as yet. Yet having someone out there, pushing for the development of the technologies that could get us out of this rural backwater and into the big cities of the galaxy, is a good thing. Unless, of course, Greg Benford and Charles Pellegrino and not Carl Sagan are right about how dangerous the rest of the galaxy might be. And that really is the big thing. I am not saying that we shouldn't head out into the big galaxy - we should. Earth is the cradle of mankind, and we can't stay in the cradle forever. And if Earth is the cradle, the Solar System is the nursery. We don't know, yet, whether the universe outside the nursery is a barren desert, a civilised utopia, or a particularly savage part of the Bronx after sundown. Given the fecundity of life on earth, and the size of the galaxy, I think the barren desert is unlikely. There will be life, somewhere. Probably manywheres. If some of that life is sentient, the chances of a enlightened utopia is vanishingly small. Perhaps we, or some other race, might unify and be nice. All of them? At the same time? It only takes one to ruin the party, and someone is going to be nasty. When the outcome of an interstellar war could be species extinction, how many races will take a chance on being nice?
I don't think we will draw much attention to ourselves expanding into the solar system. Whatever technology we end up using to travel starward, we will likely need the resources of the solar system to accomplish the journey - massive solar power stations harvesting the energy of the sun to create antimatter, or perhaps something even more odd. When we head out, though - that's different. We will not only draw attention to ourselves, we will have proved that we have the capability of wreaking havoc on anyone in our neighborhood. A relativistic spaceship is indistinguishable from a relativistic bomber.
We're not there yet. But technology isn't just increasing. It isn't even accelerating. The rate of acceleration is increasing. We might be there quicker than even the most optimistic appraisals allow for, even not counting the singularity. It seems funny to talk of interstellar travel when we can barely get into orbit, but we went from not even being able to fly to walking on the moon in 66 years. Once we're in space, the expansion could be quite quick indeed.