Argo
From Spacefaring
Argo was a 2009 spacecraft mission concept by NASA to the outer planets and beyond. The concept included flybys of Jupiter, Saturn, Neptune, and a Kuiper belt object. A focus on Neptune and its largest moon Triton would have helped answer some of the questions generated by Voyager 2's flyby in 1989, and would have provided clues to ice giant formation and evolution.