The Red Scare period from 1947-1957 led to widespread fear in the US of communist takeover. The House of Un-American Activities Committee investigated thousands of Americans, accusing many of being communists through "loyalty tests". Senator Joseph McCarthy furthered these anti-communist efforts, though eventually lost credibility by accusing the wrong targets. During this time, Hollywood faced blacklists and the Rosenbergs were executed for espionage. Americans lived in fear of nuclear attack from the USSR and radiation fallout. The launch of Sputnik heightened these fears and led the US to create NASA and join the Space Race.