What type of lander could touch down on Jupiter’s volcanic moon, Io? This is what a recent paper presented at the AIAA 2025 Regional Student Conference hopes to address as a team of student engineers from Spartan Space Systems at San Jose State University investigated a novel concept for landing a spacecraft in Io, which is the most volcanically active planetary body in the solar system. This study has the potential to help scientists and engineers develop new mission concepts from all levels of academia and industry.
For the study, the researchers introduced UNAGI, which is a unique mission concept that is designed to use Jupiter’s magnetic field as “propellant” to lower it to Io’s surface without the need for actual propellant for its descent. The team notes how UNAGI gets its inspiration and technological concepts from a myriad of active space missions, including NASA’s Juno, Europa Clipper, and the European Space Agency’s JUICE (Jupiter Icy Moons Explorer) spacecraft. Of the three, Juno is the only one actively studying Jupiter, while Europa Clipper and JUICE are currently en route to the solar system’s largest planet and its moons.
The team refers to this landing method as the electrodynamic tether (EDT) propulsion system that uses Jupiter’s powerful magnetic field to interact with the lander’s 50-kilometer (31-mile) tether, thus enabling corrections during the lander’s descent and will deploy airbags upon touchdown. Once this occurs, the scientific payloads will begin their mission of examining Io’s internal composition, surface changes from volcanic activity, outgassing and plume activity, tectonic activity, Io’s interactions with Jupiter’s magnetic field, and comparing Io’s processes with the other Galilean moons (Europa, Ganymede, and Callisto).
“Within the context of deep space and even near earth missions, propellantless propulsion is necessary and important for several reasons,” the study notes. “Using an EDT maximizes fuel economy by leveraging the environment our spacecraft operates in. This can free up mass allocations to boost payload or other subsystems. An EDT system can also reap benefits through longevity. If satellites or probes never need to refuel they can theoretically stay in orbit for much longer, potentially indefinitely. All of these useful attributes ultimately contribute to the most useful thing about the EDT system: cost.”
As noted, Io is the most volcanically active planetary body in the solar system, exhibiting hundreds of active volcanoes and lava fields. This volcanic activity is caused by Io’s interaction with Jupiter’s massive gravity that stretches and compresses the much-smaller moon during the latter’s orbit, which is more eccentric (oval-shaped) than Earth’s. While Io only takes 42.5 hours (1.77 days) to orbit Jupiter, Io’s distance to Jupiter changes during this time, bringing Io closer and farther from Jupiter throughout its orbit. When Io is closer, it’s compressed from Jupiter’s gravity, and when it’s farther away, this tension is released. Over millions of years, this stretching and compressing leads to friction within Io, which leads to heat, thus the hundreds of active volcanoes we see today.
While NASA’s Juno spacecraft has obtained several images of Io, the only spacecraft to have studied Io in depth is NASA’s Galileo spacecraft, which studies Jupiter and its Galilean moons from December 1995 to September 2003. During this time, Galileo obtained countless images of Io’s surface, including active plumes, calderas, and lava fields. Given the active volcanism on Io’s surface, landing a spacecraft might prove difficult, but this study demonstrates how new concepts could pave the way for landing the first spacecraft on a volcanically active world, thus teaching us about its formation and evolution.
How will UNAGI help researchers land on Io in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!