In my view, this misses the mark. The primary benefit is the second-order effects. Inspiring the next generation of scientists, engineers, and innovators. New technology developed in the process that improves life on Earth. New scientific advancements. A deep feeling of awe and wonder, that ignores borders and nationalities, and brings us closer together as a species.<p>Now from an economic and investment standpoint. The most important angle here is one of <i>marginal benefit</i>. If we are already spending 100 billion a year on disease, poverty, and climate change (this is a very conservative guess), how much good is adding a few billion more? It's likely not going to move the needle extensively. However, that money that will make an enormous difference in our space endeavors, letting us reap some of those second order benefits.<p>This idea is core to approaches that involve casting a wide net or diversifying your efforts -- essential strategies for when information/understanding is incomplete and the possibility space is broad. Very much like where we are at today.<p>Lastly, we need to look longer term. A space program is essential in moving humanity into the next technological era, and will likely have many unforseen positive benefits. Looking at the two paths, I think 200 years now, all else being equal, the GDP and happiness quotient of a society that invests in space exploration will be significantly higher than in one that doesn't.<p>P.S. This is also a bit ironic coming from Bill Gates, given the impact the space program had on the nascent computing industry:<p><a href="http://www.computerworld.com/article/2525898/app-development/nasa-s-apollo-technology-has-changed-history.html" rel="nofollow">http://www.computerworld.com/article/2525898/app-development...</a>