Which president instituted the Space Shuttle Program?

On January 5, 1972, President Nixon announced that the development of a space shuttle system would be in the best interests of national defense and would be less expensive in the long run than individual rocket launches. The name that was selected for the first orbiter was Constitution. After an intense campaign by supporters of the "Star Trek" television show the inaugural shuttle was renamed "Enterprise". Enterprise was a prototype used to develop the landing techniques. The Columbia was the first shuttle actually launched into space. Ronald Reagan was president when Challenger exploded after lift-off in January, 1986.