If the $100 billion International Space Station (ISS) had been constructed to orbit our Moon instead of Earth, prospects for the U.S.’ human spaceflight program would arguably be much brighter than today.
Here are a few reasons why:
An International Lunar Space Station (ILSS) would have guaranteed the U.S. maintained its Apollo-era global dominance in terms of crewed interplanetary transport.
Even if NASA had decided not to continue with the Apollo program as originally envisioned, the space agency could have ferried astronauts to lunar orbit using its remaining Saturn V rockets and begun construction of a scaled-down version of the current ISS.