New Evidence Points To Icy Plate Tectonics On Europa (gizmodo.com)

According to new research published today in Journal of Geophysical Research: Planets, Europa has what it takes to support plate tectonics. "Using computer models, a team lead by Brown University planetary scientist Brandon Johnson was able to demonstrate the physical feasibility of icy plates driving deep into the icy interior in a processes similar to what's seen on Earth," reports Gizmodo. "Excitingly, this same process could be delivering important minerals to the ocean below, heightening the moon's status a potentially habitable world." From the report: Europa has surface features reminiscent of Earth's mid-ocean ridges. For astronomers, this hinted at geological processes akin to subduction zones, where, on Earth, tectonic plates slide underneath another, sinking deep into the planet's interior. Several years ago, researchers Simon Kattenhorn and Louise Prockter posited this explanation when they noticed that a 20,000 square-kilometer (7,722 square-mile) chunk of ice had mysteriously disappeared from Europa's surface. Their explanation was that Europa's surface, like a gigantic jigsaw puzzle, is composed of tectonic plates, and that occasionally a plate of ice will sink beneath the other into warmer layers below. But this observational evidence of extension and spreading needed to be supported by geophysical reality. To that end, Johnson's team ran a computer simulation to see if it was possible for ice to sink in this way.

On our planet, subduction is primarily driven by differences in temperature between a descending slab and the surrounding mantle. Dense crustal material features a negative buoyancy that drives it down into the mantle. The Brown University scientists figured a similar thing happens on Europa, but with ice. In the case of Europa, the researchers surmised that the moon has two frozen layers -- an outer lid of very cold ice that sits above a layer of slightly warmer convecting ice. Their models showed that subduction is indeed possible in this alien environment, but only if the outer shell contains varying amounts of salt. This added ingredient provides the necessary density differences for a slab to conduct.

Comments

Life we know it.

[dohzer]

this same process could be delivering important minerals to the ocean below, heightening the moon's status a potentially habitable world

*Habitable worlds for life as we know it.

Re:Life we know it.

[fisted]

You're so smart.

Joke aside, "as we know it" is implied because at this point we only know one way.

Re:Life we know it.

[Baron_Yam]

Most people who feel the need to add, 'for life as we know it' when the subject comes up seem to be ignorant of the reasons we have for believing it is probably very safe to say 'life' instead of 'life as we know it'.

No, Si can't replace C as a backbone for complex molecules. Yes, you need a liquid in which chemistry can happen. And a (fairly gentle) energy gradient - enough to help chemistry along without breaking molecules apart before anything interesting happens with them.

There aren't any plasma beings living in a star's corona, or balloon animals floating in the atmosphere of a gas giant. No living rocks. These are INCREDIBLY safe assumptions.

What we don't have a firm grasp on is how abiogenesis happens, or how long it takes on average to develop from a chemical soup into an intelligent animal (and what factors might reasonably be used to predict variations from the average). We don't have a great understanding of where life might successfully start and take root, other than something identical to Earth... but at least we understand it is theoretically possible to be under the crust of an icy moon, in a rogue planet with enough core heat, etc.

Re:Life we know it.

[fisted]

What about machines driven by strong AI built by some advanced life-as-we-know-it kind of civilisation, though?

Re:Life we know it.

[Baron_Yam]

I think that one is possible. I can see that being humanity's legacy - creating such a 'species'.

I also think the fact that we've never found any evidence of such is probably a pretty good indication that the difficulty of traversing the void between stars is likely insurmountable even if you're an AI in radiation-hardened hardware.

Re:Life we know it.

[Maritz]

Thanks for the super-important clarification. Just in case anyone was wondering - Europa is not being posited as a suitable planet for five-dimensional beings of pure energy, silicon based robo-life, or swarms of nano-machines.

Re:Life we know it.

[Maritz]

Hello fellow carbon chauvinist. You're right, Silicon doesn't work as a replacement for carbon. Carbon is the fucking daddy.

Re:Life we know it.

[fisted]

I also think the fact that we've never found any evidence of such is probably a pretty good indication that the difficulty of traversing the void between stars is likely insurmountable even if you're an AI in radiation-hardened hardware.

I'm not sure that's right -- on a cosmic scale we really haven't been looking for all too long yet, and we're such a small target to hit - or put differently, the universe is so huge - that even with a viable means of bridging those distances, it wouldn't seem all too likely to be run into just by chance (especially not in the short timespan in which we could actually tell what's going on). For all I know, the various stories about gods and angels and whatever might as well be based on such encounters ;)

Re:Life we know it.

[Baron_Yam]

Unfortunately, the math says otherwise.

The Earth - the one example of intelligent life in the Milky Way known to humanity - is ~4.5 billion years old, and it's taken ~4 billion years of that time to have us evolve on it to the point we can post about it on Slashdot. We don't know, however, if that's an unusually long time, or an unusually short time.

Hopefully it's long or average, because our star is near the end of it's current Earth-supporting phase. If you assume you need a Sun-like star (smaller gets you a longer-lasting star, but the habitable zone gets closer to requiring planets to be tidally locked, and stellar temperament becomes a problem, too), then you pretty much want to know people can pop up on an orbiting rock in less than 4 billion years.

Anyway, at speeds we can reach with our technology, it would take around 5 million years to cross the galaxy. 5 million years is peanuts compared to the 4 billion years life has been on Earth so far. Now consider there are probably ~10 billion potentially habitable worlds in the Milky Way based on our current models.

Only ONE of those 10 billion worlds has to have intelligent life begin to colonize the galaxy a mere 5 million years before we started talking about it to arrive by tea time tomorrow.

And the Sun wasn't the first star of its class to be born. There's at least one similar star we know of that's over 11 billion years old, which potentially means there's an extra 7 billion years of leeway for aliens to set up shop everywhere. Well, not everywhere - obviously if they were zipping around the Milky Way more than 4 billion years ago, Earth would just have been a hot damp rock. On the other hand, you'd expect that with the extra lead time, they'd be around pretty much every star in the sky and we'd have seen SOMETHING by now.

Re: Life we know it.

[cyber-vandal]

That assumes that we know what to look for.

Re: Life we know it.

[Baron_Yam]

Of course we do - anything we can't explain as a natural phenomenon.

The real (and immense) difficulty is in getting enough photons into our detectors, because the distances are vast and unless you have some silly dream of planet-sized megastructures... anything we'd look for would be tiny.

Re:Life we know it.

[LeDopore]

I bet you would like "The Vital Question" by Nick Lane. It's a very recent book that brings together quite a lot of phylogenetic, chemical, and geophysical evidence to show how like likely arose on Earth - the first plausible explanation of abiogenesis I've ever seen. Also, by his reasoning, the origin of life might not have been a fluke, but the first eukaryote - that's possibly a great filter.

Re: Life we know it.

[cyber-vandal]

That assumes we know everything about the universe and can tell the difference between natural and artificial and that time hasn't eroded the evidence.

Re:Life we know it.

[fisted]

Sorry, gmail keeps locking me out so I miss/get delayed a lot of reply notifications these days.

Anyway, at speeds we can reach with our technology, it would take around 5 million years to cross the galaxy.

I guess this is true when only considering speed. I think there's a lot more to crossing the galaxy in 5M years than velocity alone.

Only ONE of those 10 billion worlds has to have intelligent life begin to colonize the galaxy a mere 5 million years before we started talking about it to arrive by tea time tomorrow.

Dunno. This is based on the assumption that galactic colonization is a) desirable and b) happens in a von Neumann probe sort of way, which would be a different matter altogether.

Re:Life we know it.

[Baron_Yam]

> I think there's a lot more to crossing the galaxy in 5M years than velocity alone.

Agreed. But humans have gone from banging rocks together to the space and information age in 200,000 years. That's basically 'from scratch'. Now imagine you've arrived at a new planetary system having foreknowledge of the available resources, and brought all your tech know-how and a 'starter kit' with you.

I think you'd have to agree that the amount of time required to jump off to the next candidate planetary system would be insignificant compared to the travel time, especially towards the end of the process of spreading out as there are fewer and fewer unexploited systems to head to and more and more groups looking for them.

I mean, you're perhaps talking an average of thousands of years of travel between destinations... I think a couple of hundred to get established and send someone off on the next hop isn't much to worry about.

5.5 million years, then? IF it is at all practical given the difficulty and required investment.

>This is based on the assumption that galactic colonization is a) desirable

Staying in one place gets you extinction, guaranteed. (Of course, on a long enough timescale, so does any other conceivable action) Still, given the tech to do it, people explore. If we didn't we'd have died out millions of years ago as dull little primates that didn't feel like leaving their little patch of savannah. Similar truth should apply to any other intelligent life out there.

>and b) happens in a von Neumann probe sort of way, which would be a different matter altogether.

If the first group wants to spread out, there's not much reason to suspect their descendants wouldn't be the same way. Humans in colony ships or self-replicating probes... it's a minor difference in schedule. Either way, technology spreads like an infection across the galaxy (which is meant to describe the spread, and not communicate any positive or negative associations).

Incorrect moderation

[mccalli]

Posting to undo a misclick and incorrect moderation - please ignore.

All these worlds are yours except Europa

[Anonymous Coward]

Attempt no landing there.

Re:All these worlds are yours except Europa

[syn3rg]

Would have been an appropriate first post; shame you missed it.

Re:All these worlds are yours except Europa

[segedunum]

You just know humans are never going to pay attention to that kind of rule.

Minerals?

[Viol8]

Where from? The amounts of rock minerals from space dust and organics from reactions on the surface are probably minute. I suspect any significant minerals come from the moons core which AFAIK is thought to be made of rock.

Anyway, we have no idea what conditions are required for life to start. There may well be a minimum energy requirement which europa doesn't even get close to. Also you need some kind of energy gradiant. In an ocean sealed off dozens or even hundreds of km below the surface I suspect that gradient is shallow in the extreme.

Re:Minerals?

[Anonymous Coward]

Great job guessing based on nothing.

Re:Minerals?

[Viol8]

Well if you consider numerous articles I've read on the subject and a science background nothing, then sure. But feel free to elaborate your ideas, if you have any and you're not just another A/C troll.

Re:Minerals?

[Rei]

Well, then, since you feel qualified to weigh in on the amount of rocky mass recycled from the icy crust, off the top of your head you should be able to tell us the mass flux from impactors and space dust at Europa. What is it?

Because I guarantee you, people who study these things don't need to google it.

Re:Minerals?

[Dorianny]

The earliest claimed fossilized lifeforms on earth are as old as old as 4.28 billion years old. it suggests an almost instantaneous emergence of life after oceans formed 4.4 billion years ago. Obviously Europa doesn't have the same conditions as early earth but perhaps the Abiogenesis is simply slower instead of impossible under those conditions and Europa has had plenty of time. We just don't know

Re:Minerals?

[Anonymous Coward]

"Well if you consider numerous articles I've read on the subject and a science background nothing, then sure" - Right, so nothing then.

Re:Minerals?

[necro81]

Where from? The amounts of rock minerals from space dust and organics from reactions on the surface are probably minute.

Io is right next door (so to speak), and spews forth a lot of material from its volcanoes. Some of that material makes it into the Jovian space between the moons. Jupiter's magnetic field is a transport mechanism.

Also: we know that tons - literally, tons - of extraplanetary material rains down on the Earth each day. Jupiter, being as massive as it is, probably sucks up a lot more. Europa is a small target, but is traveling through this inward flux of material and is sure to pick some up.

Re:Minerals?

[Viol8]

So you don't read, you just make it up. Got it. Glad we cleared that up.

Re:Minerals?

[Viol8]

Very little I should think given the amount of ice still visible on calisto and ganymede especially in craters, which almost certainly don't have any kind of crustal convection. If it was any significant amount then these moons would be jet black after 4 billion years. So go ponder that one you smug bastard.

Re:Minerals?

[Viol8]

Some sure, but the other moons of jupiter would be jet black even in their craters if it was any significant amount. Since there're not, it obviously isn't.

Re:Minerals?

[Anonymous Coward]

Anyway, we have no idea what conditions are required for life to start. There may well be a minimum energy requirement which europa doesn't even get close to. Also you need some kind of energy gradiant. In an ocean sealed off dozens or even hundreds of km below the surface I suspect that gradient is shallow in the extreme.

Features such as Conamara chaos show extensive melt-through and rafting. That does not happen with an icy crust hundreds of kilometres thick.

The ice shell is probably less than 10km thick in most places and occasionally much thinner. Gives ample opportunity for surface materials (irradiated by the sun and radiation from jupiter) to be recycled into the subsurface ocean.

Re: Minerals?

[Anonymous Coward]

Except the surface of Europa is red-brown specifically because something is accumulating. The two competing ideas are either it is organic compounds due to UV interacting with carbon and nitrogen coming from below the ice, or a combination of sulfur and magnesium coming from off the moon. Results of Galileo lean toward the latter. Depending on the geology of the rock below the ice and ocean, sulfur from rock may be very small compared to what hits the surface.

You can't just say the amount hitting the surface is insignificant because it isn't black. The amount is enough to visually change the surface, but that also doesn't tell you whether it is significant enough to impact life or not. You need to compare the amount from other sources, e.g. from the rocks and vulcanology below the surface. That takes actual numeric estimates to compare, not just shooting from the hip. Unfortunately the papers I am familiar with enough are behind a paywall.

Re:Minerals?

[Anonymous Coward]

moons core which AFAIK is thought to be made of rock.

So we could have Icy plate tectonics AND conventional plate tectonics. Yay!

Re:Minerals?

[wbr1]

As you stated above with "I should think" indicates you have no practical knowledge of the subject at hand either. You just want to be 'internet correct' the best kind of correct.

I have no specific knowledge either, but I know Rei is highly intelligent and from past posts probably works in the field, even if this subject is not his direct area of study.

All that bitching aside, here is a paper with some numbers for you: http://people.virginia.edu/~re...

If Io were the only source of non-ice material to Europa’s surface and no loss occurred, then using the flux values from Table 1, sulfur compounds could be present on the surface at ~7% (molar abundance) relative to H2O, while Na and Cl could reach 0.3%. Silicon and magnesium could be comparable or slightly less than Na and Cl. These estimates assume uniform mixing and ignore hemispherical flux and gardening rate differences, which can produce surface concentrations that are a factor of 10 or more different between the leading and trailing sides (see Fig. 2 and caption).

Seems to me that there could be quite a bit of material present. Much from Io outgassing and 'splash' from impactors to IO settling on Europa, not even counting direct impacts to Europa.

Science.. try it sometime.

Re:Minerals?

[Dread_ed]

One contribution on the possible source of minerals, if I may.

Jupiter is *the* gravitational trash compactor for the whole solar system. Earth collects around 50 tons of space dust a day, and that doesn't include the significant larger chunks of stuff that fall intermittently. We're in the kiddy pool version of gravitationally stretched space, at least compared to the Mariana Trench that that is Jupiter. I would imagine a commensurately greater amount of crap is swirling in the region of Jupiter and as a result, frequently transecting the orbit of Europa.

With plate tectonics occurring on Europa's ice surface, everything with a density greater than water which lands on the surface will eventually end up on the ocean floor. All that interstellar detritus, raining down from melting ice-magma above like marine snow, collecting in undersea crevices and crannies: a chemocline forming undersea primordial pools of concentrated space junk.

Agreed on the energy gradient. I haven't looked into estimates on the amount of tidal heating needed to maintain a squishy middle layer sandwiched between outer ice and rocky core. It may or may not be enough to create an analogous structure to our own incredibly convenient hydrothermal vents.

So minerals maybe; gradient still questionable.

Thanks for the thoughts.

Re:Minerals?

[Viol8]

You have a go at me for saying "I should think" , then you say "Seems to me".

On your bike you hypocrite.

Re:Minerals?

[Rei]

"Very little I should think" - Fail

Re:Minerals?

[wbr1]

Unlike you however, I openly admitted to having little knowledge aside from a cursory glance at a paper on the subject. That is far from hypocritical.,br> You on the other hand seem to want to be acknowledged as an expert with little more than a 'fuck you I'm smart". But I think most here can see through your ego.

Re:Minerals?

[Viol8]

"You on the other hand seem to want to be acknowledged as an expert"

Seriously? Which part of "I suspect" and "There may well be" in my original post do you have a problem comprehending, because its seems like simple fucking english to me. If english is your second language I'd suggest learning it a bit better, if not then
buy yourself a nice spade for christmas, it'll help you did that hole even faster.

Silly idea to name a moon like a continent

[gotan]

The first picture that came to my mind were some giant ice sheets covering Europe doing some strange kind of tectonics.

Btw. I'm German, in which both items are spelled "Europa", and it took a few seconds to remember the moon and that the continent would be spelled "Europe" in English.

Of course in terms of Greek mythology it all makes perfect sense ...

Re: Silly idea to name a moon like a continent

[Bruno Braganca]

As a brazilian, I share your frustration, in Portuguese both are Europa too.

Re:Silly idea to name a moon like a continent

[Anonymous Coward]

The moon was named after a character in Greek mythology, by an Italian.

Re:Silly idea to name a moon like a continent

[Hal_Porter]

Europa the moon and Europe the continent are both named after the same mythical character

https://en.wikipedia.org/wiki/...

Re:Silly idea to name a moon like a continent

[lorinc]

I had exactly the same mental image as you. In French, both the continent and the moon are spelled "Europe", which is as confusing. I had to read the summary twice to remember that Europa is the moon.

I suggest we add Europa as the newest 28th state of the EU (now that the brits are out).

Re:Silly idea to name a moon like a continent

[Anonymous Coward]

The first picture that came to my mind were some giant ice sheets covering Europe doing some strange kind of tectonics

Plate tectonics on Earth means less dense rock (granite - continental pates) sliding over dense basaltic rock (the bedrock). In Europa there's no way the denser layer of ice is bellow surface. The denser ice will be that ON the surface. So it would tend to sink through the less dense ice bellow.

Plate tectonics is a great misnomer for whatever is happening in Europa.

Re:Silly idea to name a moon like a continent

[Anonymous Coward]

Man, Zeus is kinda a sick god.

Raping his own great-granddaughter, and the granddaughter of his brother.

I guess when you are king of the gods they just let you get away with whatever.

Re:Silly idea to name a moon like a continent

[Hal_Porter]

Zeus was beyond good and evil, in the Nietzschean sense. A bit like Trump!

Damn. Every time as a German ...

[Anonymous Coward]

... I think people mean my continent!

Imagine a German-dominated world, with you reading a German new site, where that moon would be called "America". Totally different from the continent "Amerika" of course, so no confusion there! /s

I *just* commented on that.

[Anonymous Coward]

*Then* I see your comment. ^^

Hey, how about WE call the moon "America" (as opposed to the continent "Amerika"), and confuse the hell out of *them*. ^^

Re:I *just* commented on that.

[Anonymous Coward]

I vote for Iapetus being called America.

- A mix of black and white on the surface, but due to its history, they're mostly separated.
- The distribution of its "assets" (mass) is far from equilibrium.
- A violent history
- A bulging waistline (with a belt)
- Elected a mentally-challenged racist as its president (I assume based on no evidence)

Tidal Forces

[Ayano]

I always anticipated this. Tidal forces affect liquids far more than rock or hot pressurized rock (mantle). I mean IO doesn't have anywhere near the amount of water that Europa does and it's being torn and scewed by these immense forces.

I don't see how this makes it more habitable however as large glacial tectonic forces, while similar is appearance to regulr tectonics don't seem to make life any easier on the surface. If anything it makes it more difficult to establish any kind of surface base given how quickly the ice can shift compared to normal mantle based tectonics.

Re:Tidal Forces

[eddeye]

I don't see how this makes it more habitable however as large glacial tectonic forces, while similar is appearance to regulr tectonics don't seem to make life any easier on the surface.

Who cares about the surface? We're talking about a subsurface ocean. Get over your "topdweller privilege", man. Subterranean lives matter!

Re:Tidal Forces

[Anonymous Coward]

Plate tectonics allow material to be brought up from the depths. That material can be rich in minerals.

We've been warned

[gazelam]

All these worlds are yours - except Europa ATTEMPT NO LANDING THERE.

Re:We've been warned

[Anonymous Coward]

All these worlds are yours - except Europa
ATTEMPT NO LANDING THERE.

I can't stand this meme no more. Please just STOP;

Ah headlines, you got me again

[jbmartin6]

There isn't any new evidence. Just a simululation confirming the possibility.

Stay away from Europas

[boudie2]

Lots
Of
Trouble
Usually
Serious
Damn Colin Chapman!

Remember Pluto!

[Anonymous Coward]

I know the youngsters will find this astounding... remember when the solar system had nine planets?

Re:The Klan is only getting bigger

[Maritz]

Aren't you glad you're not a niiger?

Sharing DNA with a mouth-breather like you is definitely a sad and sobering realisation.

By the way, it's two Gs. One I. You stupid cunt.

Calling Antarctica Traffic Control!

[Anonymous Coward]

Ripley here!

Space is fake. Earth is flat. The eclipses prove it.

Don't try looking for Earth's rotation in a gyroscope, and stay the heck away from Antarctica!
Attempt no landing there.

Moon Anniversary! Fake it till you make it!

[Anonymous Coward]

So Arstechnica runs some fake moon landing celebration, and on the first story there is a fake picture of Apollo 4 with the full moon behind it. Even a few Ars-tards noticed this fake picture. What's wrong with you, Slash-bots?

With a few careful observations, you can begin to understand that the
heliocentric model is a lie, and you live on a flat plane.

Watch a gimbaled, powered gyroscope spin for 15 minutes. The Earth should have rotated 3.75 degrees. The gyroscope will not move, not even a little, based on your latitude. Watch it for 1 hour, 15 degrees of Earth spin. No movement. Now set it on a platform spinning 15 degrees an hour. Movement!

Solar Eclipse: https://vimeo.com/230976895
Corona not shaped in a spherical configuration; orients toward Earth. Corona lines can be observed to move faster than the speed of light. Light of the corona can be observed on the back of the moon. Light of the chromosphere can be observed on the back of the moon. Light of protuberences can be observed on the back of the moon. Sun and Moon same size and near. Wiki: Allais Effect

Lunar Eclipse: https://vimeo.com/92378881
Irregular shadow shape, progression. Shadow is black, then changes color to reddish: Shadows don't change color. Moon glow of uneclipsed portion increases as shadow becomes reddish, detail lost. Moon has no rotation(see Nikola Tesla): we always see the same face. Moon emits own light. Craters not from impacts: Too round.
No model of the lunar eclipse correctly captures it:
https://www.washingtonpost.com/news/capital-weather-gang/wp/2014/10/06/why-does-the-moon-turn-red-during-a-lunar-eclipse/
https://www.timeanddate.com/eclipse/in/usa/scottsdale?iso=20140415
Next lunar eclipse: January 30/31, 2018 North America

Story Is Incorrect

[Anonymous Coward]

New Evidence Points To Icy Teutonics On Europa

Not in the summer. It's too warm in Germany then.

Re:The Klan is only getting bigger

[Anonymous Coward]

I AM a n166er, you insensitive clod!

Damn Millennials

[Anonymous Coward]

Get your lazy self-entitled azzes off the couch and stop running computer simulations like some sort of pseudo scientific video games and send some probes dammit! NASA used to staffed by men that walked on the moon and sent probes to the planets, not sit around in trendy coffee shops in their skinny jeans nibbling on avocado toast.

Ugh. Science?

[DarthVain]

As par for the course I didn't RTFA. So I don't know if the title and summary have nothing to do with each other and follow the inflammatory trend of clickbait or not.

However I'm not sure what "New Evidence" they are referring to other than someone built a simulated model. A model demonstrating something isn't exactly evidence. Depending on the parameters, you can build a model to show just about anything you want to show. If you are trying to show ice tectonics by using a model, I'm pretty sure you can do it. Now if there was some new parameter that they used in said model to prove something that might be a different story.

I think all houses have roofs. I drew a picture of a house with a roof. Ipso Facto this is proof that all houses have roofs. Ugh. Go Science!