I strongly disagree with the idea that space exploration is silly. First, space exploration doesn't decrease the ability to house the homeless, feed the starving, or cure diseases. It's not an either/or proposition, all can be done. Additionally, the engineers at NASA probably can't really do anything to actually cure diseases. They’re not, ya know, disease curers, they're engineers.
Second, space exploration in the past has made important contributions to the world as a whole and there are significant reasons that it will continue to do so in the future. Each and every member of this forum enjoys the benefit of these contributions on a daily basis.
If it wasn't for government funded space exploration, satellite technologies would be no where near what they are today. Instant world-wide communications wouldn't exist.
If it wasn't for government funded space exploration, this forum wouldn't exist, the internet probably wouldn't exist, and the computer industry would be decades behind where it currently is. The Apollo program consumed the vast majority of the computer chips produced in the 60's. This huge demand spurred on technology and created the initial demand that got the suppliers working. This effectively jump-started the computer industry. With out it, it would have years or even decades before the industry grew to the size it was at the end of the Apollo program and today personal computers would still be a rarity. As just a small example of things that we would be with out: Hybrid cars, detailed weather forecasting, well coordinated large scale rescue efforts, and many, many life saving drugs.
Future space exploration has the potential to bring just as much or more improvement to everyone’s lives. A moon base, a mars base, and a trip to mars all pose significant technological and scientific challenges. The solutions to these challenges will filter down into everyone's lives, most likely with a very good out come. A significant problem is energy sources. The work done by NASA could improve alternative energy sources or come up with completely new ones. Even further, the solar system has an abundance of raw materials, which could be collected and used with a significantly advanced space program. Over population is a major issue today and will be a desperate problem in the future. Space exploration will lead to making self sustaining habitable locations outside of Earth, easing the population problem. Some of these ideas will come to fruition because of space exploration and some benefits will result that no one even dreamed of.
Over all, space exploration is a very good thing.