Uranus' Moon Miranda May Have an Ocean Beneath Its Surface, Study Finds (phys.org) 33
A new study suggests Uranus' moon Miranda may harbor a vast subsurface ocean, challenging previous assumptions about its frozen state and positioning it as a potential ocean world alongside other icy moons. Phys.Org reports: Among the moons in the solar system, Miranda stands out. The few images Voyager 2 captured in 1986 show Miranda's southern hemisphere (the only part we've seen) is a Frankenstein-like hodgepodge of grooved terrain quartered off by rough scarps and cratered areas, like squares on a quilt. Most researchers suspect these bizarre structures are the result of tidal forces and heating within the moon. Caleb Strom, a graduate student at the University of North Dakota who worked with Nordheim and Alex Patthoff of the Planetary Science Institute in Arizona, revisited the Voyager 2 images. The team set out to explain Miranda's enigmatic geology by reverse engineering the surface features, working backward to uncover what the moon's interior structure must have been to shape the moon's geology in response to tidal forcing.
After first mapping the various surface features like cracks, ridges and Miranda's unique trapezoidal coronae, the team developed a computer model to test several possible structures of the moon's interior, matching the predicted stress patterns to the actual surface geology. The setup that produced the best match between predicted stress patterns and observed surface features required the existence of vast ocean beneath Miranda's icy surface some 100-500 million years ago. This subsurface ocean was at least 62 miles (100 kilometers) deep, according to the study, and hidden beneath an icy crust no more than 19 miles (30 kilometers) thick. Given Miranda has a radius of just 146 miles (235 kilometers), the ocean would have filled almost half of the moon's body. "That result was a big surprise to the team," Strom said.
Key to creating that ocean, the researchers believe, were tidal forces between Miranda and nearby moons. These regular gravitational tugs can be amplified by orbital resonances -- a configuration where each moon's period around a planet is an exact integer of the others' periods. Jupiter's moons Io and Europa, for example, have a 2:1 resonance: For every two orbits Io makes around Jupiter, Europa makes exactly one, leading to tidal forces that are known to sustain an ocean beneath Europa's surface. These orbital configurations and the resulting tidal forces deform the moons like rubber balls, leading to friction and heat that keeps interiors warm. This also creates stresses that crack the surface, creating a rich tapestry of geologic features. Numerical simulations have suggested that Miranda and its neighboring moons likely had such a resonance in the past, offering a potential mechanism that could have warmed Miranda's interior to produce and maintain a subsurface ocean.
At some point, the moons' orbital ballet desynchronized, slowing the heating process so that the moon's insides started to cool and solidify. But the team doesn't think Miranda's interior has fully frozen yet. If the ocean had completely frozen, Nordheim explained, it would have expanded and caused certain telltale cracks on the surface, which aren't there. This suggests that Miranda is still cooling -- and may have an ocean beneath its surface even now. Miranda's modern-day ocean is probably relatively thin, Strom noted. "But the suggestion of an ocean inside one of the most distant moons in the solar system is remarkable," he said. Miranda wasn't predicted to have an ocean. With its small size and old age, scientists thought it would likely be a frozen ball of ice. Any leftover heat from its formation was assumed to have dissipated long ago. But as Patthoff pointed out, predictions about ice moons can be wrong, as evidenced by Saturn's moon Enceladus. The study has been published in The Planetary Science Journal.
After first mapping the various surface features like cracks, ridges and Miranda's unique trapezoidal coronae, the team developed a computer model to test several possible structures of the moon's interior, matching the predicted stress patterns to the actual surface geology. The setup that produced the best match between predicted stress patterns and observed surface features required the existence of vast ocean beneath Miranda's icy surface some 100-500 million years ago. This subsurface ocean was at least 62 miles (100 kilometers) deep, according to the study, and hidden beneath an icy crust no more than 19 miles (30 kilometers) thick. Given Miranda has a radius of just 146 miles (235 kilometers), the ocean would have filled almost half of the moon's body. "That result was a big surprise to the team," Strom said.
Key to creating that ocean, the researchers believe, were tidal forces between Miranda and nearby moons. These regular gravitational tugs can be amplified by orbital resonances -- a configuration where each moon's period around a planet is an exact integer of the others' periods. Jupiter's moons Io and Europa, for example, have a 2:1 resonance: For every two orbits Io makes around Jupiter, Europa makes exactly one, leading to tidal forces that are known to sustain an ocean beneath Europa's surface. These orbital configurations and the resulting tidal forces deform the moons like rubber balls, leading to friction and heat that keeps interiors warm. This also creates stresses that crack the surface, creating a rich tapestry of geologic features. Numerical simulations have suggested that Miranda and its neighboring moons likely had such a resonance in the past, offering a potential mechanism that could have warmed Miranda's interior to produce and maintain a subsurface ocean.
At some point, the moons' orbital ballet desynchronized, slowing the heating process so that the moon's insides started to cool and solidify. But the team doesn't think Miranda's interior has fully frozen yet. If the ocean had completely frozen, Nordheim explained, it would have expanded and caused certain telltale cracks on the surface, which aren't there. This suggests that Miranda is still cooling -- and may have an ocean beneath its surface even now. Miranda's modern-day ocean is probably relatively thin, Strom noted. "But the suggestion of an ocean inside one of the most distant moons in the solar system is remarkable," he said. Miranda wasn't predicted to have an ocean. With its small size and old age, scientists thought it would likely be a frozen ball of ice. Any leftover heat from its formation was assumed to have dissipated long ago. But as Patthoff pointed out, predictions about ice moons can be wrong, as evidenced by Saturn's moon Enceladus. The study has been published in The Planetary Science Journal.
No swimming (Score:2)
Re: No swimming (Score:3)
*additional fees apply, one way ticket only, pictures for illustration purposes only.
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Probably super cooled brine at best.
Unlikely. Brine is concentrated saltwater, which means it is more salty than seawater.
That is unlikely on any of the "water moons" in our solar system.
Water is plentiful in the solar system, more abundant than any other molecule except H2, but sodium and chlorine are not. So, the water on Miranda is likely very dilute.
Earth has salty oceans only because we have so little water. Although Earth is a hundred times the size of Europa, it has only half as much water.
LAWKI requires plenty of electrolytes (It's wh
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SUA make for ULW!
SUA = Single Use Acronyms
ULW = Unnecessarily Long Writing
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So Uranus is full of liquid?
Sheesh, it's like shooting fish in a barrel.
Smash Miranda on Mars. Solved! (Score:2)
Plenty of water on Mars to cultivate it!
Reapers? (Score:2)
Re: Reapers? (Score:2)
I think you meant reavers, but nice try
Water is plentiful (Score:2)
Many moons, including our own, appear to have significant water ice. Some are voluminous subsurface oceans. Saturn's rings are almost entirely water ice. Mars looks to have plenty of water ice too. Indications are that Venus once had lots of water before boiling it off. Comets are primarily water ice and it looks like many asteroids also hold lots of it.
Come to think of it, H2O is a rather simple, sturdy, and very easily formed molecule. And no need for controlled conditions for it to form.
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Venus once had lots of water before boiling it off.
Venus still has plenty of water, but it is mostly in clouds of H2SO4.
We can harvest the cloud droplets, strip out the sulfur, and get H2O and molecular oxygen.
The clouds extend up to 30 km, where the temperature is a balmy 75F / 25C, and atmospheric pressure is one atm.
Venus's atmosphere is mostly CO2, so an Earth-like O2/N2 atmosphere would provide plenty of buoyancy without requiring pressurization.
We could build a Sky City like in Empire Strikes Back.
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:) Okay so its not all gone. But I'll put that in the trace amounts category I think.
Actually, the amount of extreme high pressure (and temperature) liquid water stored deep in a planet/moon is a whole other category and might be substantial even for Venus. I'm suspicious most of Earth's abundance came more from this than from later bombardment.
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Nestle isn't going to like that news.
Miranda (Score:2, Funny)
You have the right to remain silent...
Miranda? (Score:5, Informative)
Isn't there a slight problem they're overlooking?
This is us, at Earth, and here's Miranda.
All along here, that empty space in between, that's Reaver territory.
They just float out there, sending out raiding parties.
Nobody ventures there.
Re: Miranda? (Score:2)
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Who is modding this "Informative?" He's making a reference to a work of fiction [wikipedia.org]. It's really funny, but also not true.
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So, it has been modded inaccurately. I didn't complain about the content at all; n your haste to pick a fight you overlooked the context of my post entirely.
Blows my mind (Score:5, Insightful)
1) Even ~40 years later, we are still getting new findings from the Voyager dataset.
2) That dataset is still the best data that we have for most things in the Uranus system. The article has links to recent work [jhuapl.edu] folks have done using JWST observations of Miranda and Ariel. But even to JWST, these moons are little more than a few pixels.
All of which makes the proposal for a flagship mission to Uranus [space.com] really exciting. Instead of a few dozen low-res images of one face of these moons, we could have full maps at 100-m/px resolution!
how can life evolve (Score:2)
If none of their creatures can get to the surface? They better not wait for the cable
17 comments already... (Score:4, Funny)
...and not a single anus joke.
Slashdot, you disappoint.
Re: (Score:3)
There was a great headline somewhere else:
"There's a wet spot near Uranus"
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I'm sorry, Fry, but astronomers renamed Uranus in 2620 to end that stupid joke once and for all.
Oh. What's it called now?
Urectum.
Re: (Score:3)
...and not a single anus joke.
Slashdot, you disappoint.
Did you hear that now that water has been found on the moon Miranda, Russia will be planning a new "special military operation" to claim the planet and its moons? Vladimir Putin states that after taking control, he will rename the planet from "Uranus" to "Myanus."
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It's not Uranus anymore. We renamed it to get rid of that old joke. Now it's called Urectum.
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...and not a single anus joke.
That's because we're grown ups. There is nothing funny to say about a moon, of Uranus.
unbelievable (Score:1)
LIES!
If Myanus had a moon I think I would know about it!
Reavers! (Score:2)
Pretty sure going to Miranda is a bad idea. The Reavers hang out and that route for some reason...