Scientists are proposing a new source of fuel for potential alien life on Europa: Radioactive elements seeping out of rocks and into the moon’s ocean, where it could generate enough energy to support living organisms.

Research presented at the annual meeting of the American Geophysical Union in New Orleans puts forth a new model for the potential for life on Jupiter’s icy moon. The new model suggests that rocks themselves, rather than the moon’s internal heat, may be the reason for Europa’s possible habitability.

NASA’s Europa Clipper mission, which launched in 2024, may be able to put this new theory to the test when it reaches the Jovian system in 2030.

Just like home

Ngoc Tuan Truong, a planetary scientist at NASA’s Goddard Space Flight Center, was inspired by extreme habitats on Earth when he developed this new theory, according to Science. On Earth, tiny organisms on the ocean floor rely on chemical reactions rather than sunlight for energy. The process is known as chemosynthesis, and it may be happening on Jupiter’s moon as well.

Europa has a vast, saltwater ocean beneath its icy shell, with more than twice the amount of water in all of Earth’s oceans combined. The presence of all this water, a key ingredient for life, has made Europa a prime target in the search for habitability beyond our own world.

Unlike neighboring ocean moons Ganymede and Callisto, Europa’s ocean is probably in direct contact with warm rock at the seafloor, according to NASA. If radioactive material seeps out of those rocks over time, its natural decay would release heat and break apart water molecules into hydrogen and oxygen ions. Microbial life would then be able to snack on the energy in those ions, sustaining its existence, the new paper suggests.

Radioactive lunch

For the study, Truong and a team of researchers modeled the concentrations of three radioactive isotopes found in Europa’s ocean: Uranium-235, Uranium-238, and potassium. The researchers then estimated the number of ions that would be released from the decay of those isotopes and found that it was enough to support quite a lot of life. The ions could feed around 1 septillion cells, or the biomass of 1000 blue whales.

Scientists had previously assumed that Europa’s rocky interior was producing enough heat to fuel life. A recent study, however, revealed that the moon’s icy crust is much thicker than previously believed, making it unlikely that the planet produces enough internal heat for life to evolve. Radioactive elements provide an alternative explanation for how Europa could produce energy to fuel primordial life.