The successful launch of Sputnik 1 was the first instance of what?

The successful launch of Sputnik 1 was the first instance of a successful launch of an artificial Earth satellite launched into outer space. This was done successfully by the Soviet Union on October 4, 1957. This launch spawned the Space Race between the United States and the Soviet Union to gain dominance over outer space technology to prevent either country from possessing a military advantage.