Before revision: Cancelled or unselected mission concepts include: Argo — A cancelled mission concept in the New Frontiers program, a flyby mission to visit Jupiter, Saturn, Neptune (with Triton) and the Kuiper belt with launch in 2019.
After revision: thumb | 220x124px | right | alt= A hexagon prism-shaped space probe with a large communications antenna, two radioisotope thermoelectric generators and long magnetometer boom, intended for orbit around Neptune |Rendering of the Triton Ocean World Surveyor, 2021Cancelled or unselected mission concepts include: Argo — A cancelled mission concept in the New Frontiers program, a flyby mission to visit Jupiter, Saturn, Neptune (with Triton) and the Kuiper belt with launch in 2019.