Ocean worlds in our solar system are attractive places in the search for life beyond Earth.
Beneath a thick, icy shell, Jupiter’s moon Europa and Saturn’s moons Titan and Enceladus likely harbor oceans, scientists believe. On Earth, the oceans teem with life, but is the same scenario possible on these frosty moons?
Future missions could reveal if ocean worlds are habitable, and if so, what kind of life could exist below the ice. Orbiters such as NASA’s Europa Clipper and the European Space Agency’s Jupiter Icy Moons Explorer will fly by Europa this decade, and a rover-size drone called NASA’s Dragonfly will launch in 2027 to reach Titan in the 2030s.
Little is known about the frozen terrain covering Europa and Enceladus, so any mission exploring the surface of these worlds could potentially have to navigate treacherous landscapes.
A concept called SPARROW, or the Steam Propelled Autonomous Retrieval Robot for Ocean Worlds, would be able to hop right over any hazards such as long ice blades called penitentes.
“The terrain on Europa is likely highly complex,” said Gareth Meirion-Griffith, JPL roboticist and lead researcher of the concept, in a statement. “It could be porous, it might be riddled with crevasses, there might be meters-high penitentes that would stop most robots in their tracks. But SPARROW has total terrain agnosticism; it has complete freedom to travel across an otherwise inhospitable terrain.”
The Buoyant Rover for Under-Ice Exploration, or BRUIE, would act in much the same way — just inside an ocean on Enceladus or Europa, rather than on land.
A rover exploring an ocean world will need to navigate on its own. The BRUIE prototype is about 3 feet (1 meter) long and has two wheels to help it roll upside down along ice. Images and data collected by the floating rover will allow scientists to study the “ice-water interface.”
Swimming beneath the ice
A small but mighty approach is a concept that would pack cell phone-size swimming robots inside a probe called a cryobot that could melt through the ice crust on Europa and Enceladus. Once underwater, the fleet of tiny swimmers could freely explore the alien ocean.
The Sensing With Independent Micro-Swimmers, or SWIM, concept has received $600,000 funding in the second phase of NASA’s Innovative Advanced Concepts program, which will allow for testing of prototypes.