Lunar missions were strong for a few years until NASA ran out of money to support them.
"Lunar missions were strong for a few years": NASA had success in the Apollo 11 mission, and then six other after it. They put 12 astronauts total on the moon, over the course of about 3 years.
"NASA ran out of money to support them": The government stopped providing money to allow these missions to happen. Therefore, NASA hasn't sent anyone to the moon since 1972.
