Ariel And Miranda, Two Moons Belonging To Planet Uranus Turn Out To Be Hosts Of Ocean

JAKARTA - Researchers found that two of Uranus's 27 moons may host oceans. Called Ariel and Miranda, these moons add plasma to the extraterrestrial environment through unknown and mysterious mechanisms.

In a new study led by the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, researchers re-analyzed nearly 40 years old energetic particle and magnetic field data captured by NASA's Voyager 2 spacecraft.

Voyager 2 is the only spacecraft so far to have gone to Uranus. The results of their research have recently been published in the journal Geophysical Research Letters.

They found that either or both moons have an ocean beneath their icy surface and are actively spewing material, possibly via plumes.

“It is not uncommon for energetic particle measurements to lead to discoveries of ocean worlds,” said space scientist at APL and lead author of the new study, Ian Cohen, in a statement quoted from the Johns Hopkins APL website, Tuesday, March 28.

Cohen and his colleagues dug back into the particle data from APL's Low-Energy Charged Particle (LECP) instrument on Voyager 2, and they found something odd: a trapped population of energetic particles.

"What's interesting is that these particles are very confined near Uranus' magnetic equator. Magnetic waves in the system would normally cause them to scatter across the latitudes, but all of these particles are squashed near the equator between the Moons Ariel and Miranda," Cohen explained.

The researchers initially attributed these features to the possibility of Voyager 2 flying via a stream of plasma injected from the planet's far tail of the planet's magnetosphere. "Injections typically have a much wider spread of particles than is observed," Cohen said.

After some deliberation, they concluded the particle most likely came from the nearby Moon.

Researchers suspect the particles emerge from Ariel or Miranda via jets of vapor similar to those seen on Saturn's moon Enceladus or through sputtering, a process in which high-energy particles strike the surface, ejecting other particles into space.

Regardless, modeling suggests the energy delivery mechanism will be the same where a constant stream of particles flows from the Moon into space, where they create electromagnetic waves.

The waves accelerate small particles into energies detectable by the LECP. This process, according to the researchers, makes the particles seen by the LECP so narrowly trapped.

However, with only one observation of the region and no data on the composition of the plasma or measurements of the full range of electromagnetic waves within it, there is no way to determine the source of the particles with certainty.

Even so, researchers have suspected Uranus' five largest moons, including Ariel and Miranda, may have subsurface oceans. Voyager 2 images of the two Moons show physical signs of geological resurfacing, including possible eruptions of frozen water on the surface.

"The data is consistent with the potentially very exciting presence of an active oceanic moon there. We can always do more comprehensive modeling, but until we have new data, conclusions will always be limited," Cohen said.