the knowledge that sent us to the moon is still lost, even if we can do “better” next time. Lost it within a few decades.
The blue prints are everywhere...the science is recorded in lots of libraries. We also know that the thing was done so we know we can do it again. We just need a practical reason and a non bankruptable one and we can do it again. Heck your cell phone has thousands of times more computing power than the computing systems aboard the Apollo craft or for that matter...a couple of modern day I7 Intel home PC’s with 16 gigs of DDR memory could run the entire Apollo program from lift off to splash down! We have no practical reasons for going to the moon right now unless we have unspoken of military or otherworldly reasons for doing so but just suggesting that sort of thing brings out predictable “you are a paranoid conspiracy mongerer” comments from the usual deep state sources.
Now if we developed cheap reliable tech that could allow regular translunar/earth space travel...as well as new bio discoveries that would mitigate radiation and the loss of bone tissue and muscular tone when in space then we might have something of a new era to be excited about! How’s that for realism!?
What does that even mean? We know exactly how the Saturn V worked, but we have no production lines to build any more, nor would we want to build a big rocket that way today (see above). Technology has evolved past a rocket that was designed in the late 1950's. You know, the Saturn V "instrumentation unit" cost close to a million dollars and had less computing power than the computer on your desk? Why would we want to duplicate that?
We know all about navigating spacecraft through deep space (how do you think we get those landers to Mars?).
We know all about keeping people alive in space for periods much longer than it takes to get to the moon. That's what ISS is for.
So what "knowledge" have we lost, exactly? We don't have working hardware or the production lines to build them. If there were a national emergency requiring us to land on the moon asap, we could be back there in five years, tops. That it takes longer than that is the result of bureaucracy, lack of funding, and lack of urgency.
NASA never made anything. NASA assembled components manufactured by various contractors. That knowledge is preserved on drawings in flat files and specifications in three ring binders.
By today, most of that knowledge is obsolete and replaced with products that are the outgrowth of the dusty files
Same is true of the methods for making the 16” steel that was used on the WWII battleships. It would take a long time to redevelop those processes.