During which decade were satellites first sent into orbit? 1940s 1950s 1960s 1970s

Answer :

The 1950s when Russia sent the first artificial satellite "Sputnik 1" (1957) https://history.state.gov/milestones/1953-1960/sputnik#:~:text=On%20October%204%2C%201957%2C%20the,accomplish%20this%20scientific%20advancement%20first.