A new study has found that two of Uranus’ moons may have active oceans pumping material out into space.
Realized that there could be more events on Uranus More than previously thought, it stemmed from the discovery of a strange feature in radiation data collected by NASA Cruise 2 spacecraft as it passed by the planet nearly four decades ago.
The new findings, regarding the moons Ariel and Miranda, also support the idea that Uranus’s five largest moons are They could have oceans under the surfacean idea suggested by the Voyager 2 flyby observations.
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The study team examined radiation and magnetic data collected by the spacecraft in 1986, long before it reached its destination outside the solar system.
The recently reported observations of Voyager 2 — the only spacecraft currently visiting Uranus — suggest that one or two of the 27 known ice giant moons added plasma particles to the Uranus system. The discovery came in the form of “trapped” energetic particles detected by the spacecraft as it left the ice giant.
How Miranda and/or Ariel could do this is currently unknown, but it is likely that there is a possible reason: one or both icy moons may have a liquid ocean beneath their frozen surface that is actively propelling plumes of material into space. . .
Similar particle-emitting moons exist around the solar system’s fellow ice giants Neptune, Uranus, and the gas giants Jupiter and Saturn. in the case of Jupiter’s moons Europe and Saturn EnceladusIt was particle examination and magnetic field data that provided the first clues that this was an oceanic moon.
“It’s not uncommon for energetic particle measurements to be groundbreaking for discovery of ocean worlds,” said study lead author Ian Cohen, an astronomer at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland. permission (Opens in a new tab).
“We made the case a few years ago, measurements of energetic particles and electromagnetic fields are important not only for understanding the extraterrestrial environment but also for contributing to the larger planetary science,” Cohen added. “Turns out this could be the case for data older than mine. It shows how important it is to get into the system and explore it live.”
Related: Why scientists want NASA to send a pilot mission to Uranus
Another look at Uranus and its moons
The results will only strengthen planetary scientists’ desire to send spacecraft to Uranus and Neptune to gather more data, resulting in a $4.2 billion proposal. Uranus main mission NASA’s next big planetary mission.
The mission isn’t ready to launch until the early 2030s, so in the meantime, researchers are digging through old data collected during Voyager 2’s flyby for new discoveries.
Cohen and team examined data collected by APL-built low energy charged particles (LECP) Instrument on Voyager 2, which marks clusters of trapped particles.
“What’s interesting is that these particles are confined very close to Uranus’ magnetic equator,” Cohen said. This was odd, he explained, because magnetic waves in the system normally cause particles to scatter, but they all converge near the planet’s equator, between Ariel and Miranda.
The team had to rule out the possibility that the solid particles detected by Voyager 2 were the result of the spacecraft flying through the plasma stream of Uranus’s magnetosphere tail. They determined that, in this case, the feature would have a wider particle spread than detected by Voyager 2, which allowed them to rule this out as an explanation for the unusual data feature.
Cohen and team then set out to explore simple physical models using their knowledge ocean moon It has been developed and obtained since Voyager 2 flew to Uranus 37 years ago to recreate data collected by the spacecraft. This shows them that profit can only come from a powerful and stable source of particles, with a special mechanism to activate them.
They ruled out other possible explanations, coming to the theory that the trapped particles came from at least one moon of Uranus, with Ariel and/or Miranda being the prime suspects. The team believes the particles were ejected in a jet of steam similar to what is seen Erupt from Enceladus. Another possible ejection mechanism is “sputtering”, a process in which a high-energy particle collides with a surface, knocking other particles into space.
“Right now it’s 50-50 whether it’s one or the other,” Cohen said, referring to the scattered hypothesis.
Whatever ejection mechanism operates in the Uranus system, the mechanism that gives this particle its energy is more or less the same.
The mechanism for this activation is likely a continuous stream of particles flowing from the moon into space, generating electromagnetic waves. These waves then accelerate some of these particles to energies large enough to be detected by LCEP instruments. This process would also keep particles trapped and thus tightly confined, as Voyager 2 saw.
More data must be collected from the region around Uranus before scientists can definitively determine that the particles came from Ariel and/or Miranda’s underground oceans.
“The data is consistent with the very exciting possibility of an active oceanic moon out there,” Cohen concluded. “We can always do more extensive modeling, but until we get new data, the results will always be limited.”
Team results (Opens in a new tab) They were presented at the 54th Annual Conference on Lunar and Planetary Sciences on March 16 and have been accepted for publication in the journal Geophysical Research Letters.
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