It has been suggested that active oceans may exist on two of Uranus’ moons.
Uranus stands out from other planets in our solar system for a variety of reasons, but mainly due to its unique characteristic of having 28 perpendicular rotations relative to other planets.
Recently, researchers from the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland have reevaluated the data collected by NASA’s Voyager 2 spacecraft almost four decades ago, which recorded the only in-situ observations of Uranus and its system during its three-day flyby in 1986.
Through their analysis of the decades-old data, they have uncovered a strange source of energetic ions in Uranus’ magnetosphere.
The findings suggest that one or possibly two of the planet’s 27 moons, specifically Ariel and/or Miranda, may be introducing plasma into the surrounding space through a baffling and unknown mechanism.
There is a fascinating possibility that either one or both of Uranus’ moons have oceans beneath their icy surfaces and are releasing material, possibly via plumes.
The lead author of the study, Ian Cohen, who is a space scientist at APL, explained that energetic particle measurements often precede the discovery of an ocean world.
The research team dove into data from the Low-Energy Charged Particle (LECP) instrument on Voyager 2, which was built by APL, and uncovered an unusual finding.
They observed a group of energetic particles that were trapped and highly confined near Uranus’ magnetic equator as the spacecraft departed the planet.
According to Cohen, magnetic waves within the system would typically cause the particles to disperse in latitude.
However, in this case, the particles were found to be confined near the equator, between Ariel and Miranda. Initially, scientists believed that this phenomenon occurred due to Voyager 2 flying through a random stream of plasma being “injected” from the distant tail of the planet’s magnetosphere.
However, this explanation was ruled out as injections usually result in a much wider spread of particles than what was observed.
The team has theorized that either Ariel or Miranda could be the source of the particles, potentially through a vapor plume similar to that of Enceladus or via a process called sputtering. Sputtering occurs when high-energy particles collide with a surface and eject additional particles into space.
According to modeling, the same energizing mechanism is likely responsible for the particles being emitted from either Ariel or Miranda.
The moons continuously release particles into space, which generate electromagnetic waves that accelerate some of the particles to an energy level detectable by LECP.
The team believes that this process could explain why the particles were so narrowly trapped. However, due to the absence of data regarding the plasma composition or measurements of the full range of electromagnetic waves, it is impossible to identify the exact source of the particles with certainty.
Nonetheless, scientists have previously suspected that Uranus’ five largest moons, including Ariel and Miranda, could have subsurface oceans.
Voyager 2 images of these moons have revealed signs of geologic resurfacing, possibly indicating eruptions of water that froze on the surface.