Challenge: Soviets on Mars before 2000

Maybe you could prevent Stalin from coming to power and allow the NEP to last longer and eventually develop into a very successful economic policy. Keep the Soviet Union out of any major wars(without Stalin, WWII might be butterflied, or at least as we know it), and later have it develop a world-class high-tech sector and research capabilities. Then space exploration might happen even faster than OTL, led by the soviets, who make it to Mars in 1989 as a crowning achievement of scientific socicialst science.

Sure the Bolsheviks weren't the nicest lot, but they could have gotten things well sorted out. It wasn't inevitable that Stalin would come along and turn the country into his own totalitarian playground, and it wasn't inevitable that the country would be devastated by the most destructive war in history. With another set of decision makers in charge, Soviet economic policy would be very different, who's to say they couldn't have gotten lucky and stumbled into something that works well.
 
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