>I've always wondered why the US never went back to the moon. Or never set up a moon base for space exploration and experimentation.

The US sent half a dozen crewed missions to the moon, and made numerous unmanned missions.

There's no dark secret - space travel is complex and expensive, travel to the moon vastly more so than simply to orbit, and money is governed by politics. When the US had the prestige of possibly beating the Soviets to the moon , there was the political and popular will to do so. But eventually, the trick simply got old, and no longer seemed worth the expense.

Now take that, and add the exponential long term cost of a habitat and mining operation on the moon with 1970's / 1980's dollars and tech. I remember there being numerous plans for a moonbase at the time, it was discussed by NASA often, but the thing is, no one could figure out how to actually make it work reasonably cheaply without seeming like a lavish and pointless boondoggle to Congress.