One of the reasons WWI broke out when it did was that the German General Staff knew that within ten years they would not be able to win a war with the Russian Empire. The USSR was a lot more backward economically than the Russian Empire, as would be expected when you cut yourself off from world trade and investment and kill large portions of your educated classes.

Serfdom was abolished in 1861, so no the USSR did not go from serfdom to the space race.