There are a lot of answers here about how expensive Apollo was, and about how those expenses haven't really gone away. Those answers are basically right: puttin

There are a lot of answers here about how expensive Apollo was, and about how those expenses haven't really gone away. Those answers are basically right: putting humans on the moon was, and would still be, enormously expensive. But there's another factor at play which I haven't seen any mention of, which is that our risk tolerance as a culture has dropped considerably since then. We went from Mercury, to Gemini, to Apollo, in an INSANELY short period of time. We went from having never launched anybody into space, to Apollo 11, in ten years; we went from never having launched a Saturn V to putting three humans on top of one in thirteen months. We lost three astronauts due to multiple design flaws in the Command Capsule, then redesigned the capsule and launched it with astronauts in it in eighteen months. None of that could happen now. And the reason can only partly be blamed on NASA losing its mojo. In truth, the entire spaceflight community has developed far a more comprehensive, reliable safety culture. But that culture is by necessity much slower than it was then. Nobody in the industry could move as quickly as NASA did in the mid 1960s. NASA of today can't - but neither can SpaceX, or Blue Origin, or Sierra Nevada, or anyone else I know of. Even if we wanted to, we would have to re-educate our engineers. Engineers are taught how to do program management starting as undergraduates. We have an entire generation of aerospace engineers who have been taught to move at deliberate, conservative speed, to make sure nobody gets killed. The human inertia inherent in our current engineering culture just wouldn't allow us to go back to the speed of the 1960's. A slower, more comprehensive safety culture costs even more money, but more importantly it requires financial support from Congress and the White House over a much longer period of time in order for a mission to make it from proposal to launch - support which is extremely hard to sustain across administrations. And (personal opinion here) society as a whole is supportive of - indeed, has demanded and driven - these changes. We would not tolerate the US government spending 2% to 3% of the entire federal budget on a manned spaceflight program, and then losing an entire crew in a pre-launch accident, and then returning to launch in 18 months.