Ice Giants Exploration Trajectory Design as a Secondary Payload in the Heliopause Exploration Mission

Ice giants, i.e., Uranus and Neptune, present a “missing link” in our understanding of planet formation, as their intermediate size between the enormous gas giants and the smaller terrestrial worlds, dynamic atmospheres with banded structures and localized storms, and powerful magnetic fields driven by hidden processes far below the clouds. However, there is not a dedicated mission for ice giants yet, and mysteries remain unrevealed. In this paper, opportunities for the ice giant exploration are analyzed. Considering an affordable and near-term ice giant exploration mission, interplanetary transfers are assumed to launch as a secondary payload in China’s solar system boundary exploration mission. Moreover, three mission scenarios are considered, which are a single Uranus probe, a single Neptune probe, and twin spacecrafts for both ice giants, respectively. The results show that it is possible to launch ice giant missions together with the China’s solar system boundary exploration mission. The Uranus probe has a chance to launch in 2028 with the heliosphere-tail exploration mission while the Neptune probe can share the earlier launch opportunity with the heliosphere-nose exploration. As for the twin spacecrafts, they can launch at the same time in 2025 but have different gravity assist sequences. This work could provide reference on the future ice giant mission planning.