Triton Hopper

Triton Hopper is a NASA lander concept designed to explore Neptune's largest moon, Triton. Instead of relying on fuel brought from Earth, it would collect nitrogen ice from the moon's surface and heat it under pressure to use as propellant. This would allow the vehicle to make multiple short rocket-powered flights—up to roughly one kilometer high and five kilometers long—to visit different sites.

The idea began as a Phase I study in 2015, then advanced to Phase II in March 2018 under NASA's Institute for Advanced Concepts (NIAC), where teams refined the design and worked on the new technologies required. The biggest technical challenge is learning how to mine the surface nitrogen ice and heat it into usable propellant.

Because Triton has only about 8% of Earth's gravity and varied terrain, a hopping vehicle has advantages. It could cross entire hemispheres and sample the thin atmosphere while airborne. During flights, it would capture images and video; while on the ground, it could photograph and analyze the surface chemistry and geology. The craft might also fly through Triton's geysers to study the material they eject.

Triton itself was first seen up close in 1989, when Voyager 2 flew past at a distance of 40,000 kilometers and discovered several cryovolcanoes. The moon is geologically active, with a young surface and few impact craters, and it has a very thin atmosphere.