The correct answer is the launch of Sputnik.
Sputnik was a Soviet made satellite that was the first to successfully orbit the Earth. After this accomplishment, many citizens were worried about Soviet technological capabilities. Americans feared that the Soviet Union would use these advancements to attack the US. This was a fear considering that the US and Soviet Union were in the midst of the Cold War. With this in mind, the US drastically increased spending on space related missions. This culminated with the US putting a man on the moon in 1969.