I think the reason we WERE able to do it fifty years ago (and potentially COULDN'T do it today) had a lot to do with a particular set of circumstances and the fact that they occurred at just the right time. I think we've all heard how it's said that we all carry around a LOT more computing power in the smart phones we keep in our pockets than the roomfuls of computers that put man into space and on the moon. But there's no doubt that technology was indeed improving on a daily basis, even fifty years ago. Transistors and computers had finally gotten to a point where it was actually realistic to think about going into space. But, why would we want to? Well, that's the other part of the equation. It's called the Cold War. The Cold War was actually started (in some ways) by technology. The atomic bombs that ended World War II also ushered in a new age of technological advances and the Cold War between the U.S. and Russia. The Cold War, and the desire by both parties to outdo their opposition in all things military and technological, led to many more technological breakthroughs. I'm sure it probably sped up many scientific advances that might have taken much longer to develop if they didn't have an angle that could potentially be seen as a benefit to one side of the Cold War over the other. If it weren't for that "unfriendly competition" would we have ever (or at least by July 20, 1969) reached the moon? It's certainly debatable.
Not too long after the end of the Apollo program and missions to the moon the Space Shuttle program took center stage. Despite ideas that I'm sure were in the backs of some (many?) people's minds, the Space Shuttle was never destined to become a jetliner to the moon or other planets. The moon kind of became a "been there, done that" sort of thing. I'm not trying to take anything away from the importance and impressiveness of what was accomplished. It's just that once John F. Kennedy's 1961 vision and mission ("I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the Earth") was accomplished there simply wasn't a real need to go there anymore--or to continue to spend the kind of money it would take to keep going there.
I certainly have no idea what the future holds as far as human space travel. Will we eventually get back to the moon? Will man someday walk on the surface of Mars? Will commercial space travel really become something truly viable? Will there actually be a market for such a thing? Who knows what will happen in this post-moon exploration, post-Space Shuttle world we find ourselves in? Not being a very scientific person I really can't answer any of those questions. I don't think I could even if I WAS a very scientific person. But what I can say is this; today we are celebrating the 50th anniversary of an extraordinary accomplishment by NASA, by the United States of America and by humanity itself. Half a century has passed since then, but time has not diminished the fact that something that had been seemingly impossible just a few years earlier was made possible. It's definitely a day to celebrate, regardless of what is happening today and what tomorrow may of may not bring.