In the 1960s, a Grand Tour to study the outer planets was proposed which prompted NASA to begin work on a mission in the early 1970s.
This prompted NASA to begin work on a mission in the early 1970s. In the 1960s, a Grand Tour to study the outer planets was proposed.
In the 1960s, a Grand Tour to study the outer planets was proposed. This prompted NASA to begin work on a mission in the early 1970s.
In the 1960s, a Grand Tour to study the outer planets was proposed. This prompted NASA to begin work on a mission in the early 1970s.