Comment by vkou

The Soviets managed to send probes to the moon, and succeeded, with the automation and remote control systems of the 60s. Their manned lunar ambitions were hamstrung by the many failures of the N-1 rocket, which could not be made safe enough for human flight. (Or any flight, really.)

The thing with probes is that you should send more than one every 5-10 years, if you do that, you'll learn something from the failures before everyone working on the project dies of old age. It's the moon, you don't need to wait for a once-a-decade transfer window to line up.