Three related reasons: Sputnik angst, there was a race with the Soviet Union in every field, and areospace technology development for military purposes.

But the fact is, the Apollo program was a one-shot thing. It was wound down and the US lost its ability to fly to the moon. It also discontinued its high-payload rockets in favour of the Space Shuttle, so now the rocket market is occupied by the European Ariane and the Russian Proton.

The Soviet manned space program made more scientific and technical sense than the American one, and the ISS owes more to the Russian Soyuz and Mir than to the American Skylab, which was also discontinued and folded into the Shuttle.

We have met the enemy, and he is us — Pogo