Europa: Minerals from an Ancient Impact?

by Paul Gilster on December 12, 2013

Europa continues to fascinate those hopeful of finding life elsewhere in our Solar System, and it’s easy to see why. Consider everything the Jovian moon has going for it. Although it’s a long way from the Sun (Jupiter is 5 AU out), Europa gets internal heat from its interactions with the gravitational well around Jupiter, which causes the moon to be stretched and squeezed. We have an ocean whose occasional eruptions into the ice above allow mixing with surface materials and, as this JPL news release points out, salts on the surface that create an energy gradient. These factors have been in place on Europa since the moon first formed.

Now an analysis of data from the Galileo mission has turned up something else needed for life: The likelihood of organic materials. The assumption has been that comet or asteroid impacts could provide these, and the data that Jim Shirley (JPL) will discuss tomorrow at the American Geophysical Union meeting in San Francisco show the presence of clay-type minerals on the moon, assumed to have been delivered by just such a collision. Says Shirley:

“Organic materials, which are important building blocks for life, are often found in comets and primitive asteroids. Finding the rocky residues of this comet crash on Europa’s surface may open up a new chapter in the story of the search for life on Europa.”

europa_clay

Image: This image, using data from NASA’s Galileo mission, shows the first detection of clay-like minerals on the surface of Jupiter’s moon Europa. The clay-like minerals appear in blue in the false-color patch of data from Galileo’s Near-Infrared Mapping Spectrometer. Surfaces richer in water ice appear in red. The background image is a mosaic of images from Galileo’s Solid State Imaging system in the colors that human eyes would see. A version of the image without the infrared area is on the right. Credit: NASA/JPL.

The pattern of the detected minerals gives us some idea about the impactor that brought them. Shirley’s work suggests an asteroid about 1100 meters across or a comet about 1700 meters in size, either of these striking at a shallow angle. The minerals, called phyllosilicates, showed up in near-infrared images from Galileo, appearing as a broken ring about 40 kilometers wide that is 120 kilometers from the center of a central crater site. We’re probably looking at the backsplash of ejected materials from a strike at an angle of about 45 degrees or more off the vertical — a head-on collision would have vaporized the impactor or driven its materials below the surface.

All this assumes, however, that the organic materials did not come from Europa’s interior in the first place. The JPL news release notes that this is unlikely because of the thickness of the icy crust over Europa’s ocean, assumed to be as much as 100 kilometers thick. But the thickness of that crust is still the cause of some controversy, and for that I turn you to Unmasking Europa: Of Ice and Controversy, which looks at Richard Greenberg’s book on the moon and discusses surface features that may indicate a much thinner crust. What we obviously need to make this call is more information, and that may translate into a Europa mission with lander capabilities.

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{ 30 comments… read them below or add one }

Rob Flores December 12, 2013 at 12:43

If we assume that there are organic materials on Europa doesn’t this mean that they could exist in liquid form beneath a layer of ice. Like a subantarctic
lake (but not as deep)?. Too bad none of these Jovians have significant atmospheres. Would the tidal heating and/or the radiation belt bleed any atmosphere out on Europa?

Forgive me for going on a bit of a tangent:
These Outer 3 Jovian moons, stand in direct contrast to Titan.
If we assume they formed with the similar solar nebula composition
Just why the heck does Titan have a Nitrogen Atmosphere but no trace of that gas is found on the Jovian moons. You might blame Jupiters gravity well, but at least the materials ring that formed Callisto should have been less affected, yet no Nitrogen Atmosphere on Callisto, matter of fact it’s the deadest moon geologically speaking of the 4.

Alex Tolley December 12, 2013 at 12:54

Graham Cairns-Smith genesis theory has clay acting as a template to align organic molecules for replication. It probably is not the correct theory and conditions on Europa are very different from Earth.

Even if Europa is a sink for cometary organics, perhaps complex ones that could not form on Europa’s surface of in the subsurface oceans, we are still a long way from there to a Europan abiogenisis. It seems far more likely to me that Earth microbial life would have migrated there and found a foothold.

Mars had decent conditions for abiogenesis early in its history and evidence that some water may still be liquid below the surface would suggest that this would be the best location for either a second genesis or contamination from Earth (or vice versa).

ljk December 12, 2013 at 13:14

Panspermia On The Moons Of Jupiter? New Study Finds It Possible, While Another Finds Evidence Of Clay-Like Minerals On Europa

By Leonidas Papadopoulos

Even though Mars receives most of the spotlight today when it comes to searching for places in the Solar System where life might have arisen besides Earth, there are many in the scientific community, who think that there are better prime candidates. And new studies and analyses of old data from the Galileo mission at Jupiter, suggests that we should turn the spotlight on Europa as well.

The idea that the seeds of life are common throughout the Universe, being propagated between planets and stars, has been around since antiquity. This notion of ‘panspermia’ was first postulated by the Greek Ionian philosopher and natural scientist Anaxagoras, in the 5th century BC. Although largely neglected for more than two thousand years afterwards, interest in the panspermia hypothesis was rekindled during the 19th and 20th centuries, by notable scientists like Jacob Berzelius, Hermann von Helmholtz and Svante Arrhenius, and later popularised by Fred Hoyle in the 1970′s.

Although once viewed as a fringe idea, panspermia slowly gained acceptance and credibility within the scientific community. The discovery of hundreds of meteorites found to have come from Mars for instance, showed that the exchange of material between planets is indeed happening. And the discovery that organic molecules that constitute the basis of life, are common throughout the interstellar medium and are also found in meteorites that have fallen to Earth, made scientists start hypothesising as to whether life on Earth was delivered from space.

A key mechanism by which life is transferred between worlds according to the panspermia hypothesis, is by asteroid and comet impacts. Although the frequent exchange of material between the neighboring Earth and Mars had been proved, many scientists have been sceptical about the possibility of such collisions taking place between distant planets, or that any organic compounds or living microbes inside asteroids or comets, would endure the shock of impact.

A new study made by Rachel J. Worth, an astronomy graduate student at Penn State University and her colleagues, aimed to address the first leg, by showing that meteoroid exchange between the inner planets and the moons of the outer Solar System could indeed be possible.

Full article here:

http://www.americaspace.com/?p=46630

Dmitri December 12, 2013 at 13:14

Europa has active geology. Before assuming existence of life the fundamental question is how “fast” Europa crust’s upper layer gets recycled. On earth we measure these events in eons. Yet Himalaya is just 250 Gya back bottom of the sea? Well, let’s assume it’s twice-trice that on Europe – is 500-750 Gya sufficient time for “life” to “evolve”? I’m actually very fond to hear the age of the impact event.

In analogy the most likely is to find life on Venus due to its thick atmosphere where meteorites would explode high in the atmosphere rather than on impact. The former event gives higher probability any biological substance / (primodial) microbs surviving the event and depending on their relative weight would probably find suitable condition in suitable atmosphere layer which pressure and thickness would not to let “sink” below.

Which again makes sense looking for signs of organic in layers of Venus atmosphere.

ljk December 12, 2013 at 13:48

Jupiter Moon Europa May Have Water Geysers Taller Than Everest

by Charles Q. Choi, SPACE.com Contributor

December 12, 2013 11:01 am ET

Jupiter’s icy moon Europa may erupt with fleeting plumes of water more than 20 times the height of Mt. Everest, scientists say.

If these giant waterspouts are confirmed, they could be a way to detect signs of any life that might exist in the underground ocean that researchers suspect Europa has, scientists added. They were spotted by comparing recent and older images of Europa taken by the Hubble Space Telescope.

Europa is about the size of Earth’s moon. Beneath an icy crust maybe 10 to 15 miles (15 to 25 kilometers) thick, investigators think Europa possesses a giant, churning ocean perhaps up to 100 miles (160 km) deep. Since there is life virtually wherever there is water on Earth, researchers have long wondered if Europa could support life.

“A subsurface ocean at Europa potentially provides all conditions for microbial life — at least life we know,” study lead author Lorenz Roth, a planetary scientist at the Southwest Research Institute in San Antonio, Texas, told SPACE.com.

To learn more about the Jovian moon, scientists analyzed ultraviolet images of Europa taken by the Hubble Space Telescope in November and December of 2012 as well as older images taken by Hubble in 1999. They concentrated on finding hydrogen and oxygen, the elements that make up water.

The research was unveiled today (Dec. 12) in the journal Science and is being presented at the annual American Geophysical Union meeting in San Francisco.

Full article here:

http://www.space.com/23923-europa-water-geyers-taller-than-everest.html

Michael Finfer December 12, 2013 at 15:37

With today’s report of probable of plumes of water spotted by the Hubble telescope, it seems likely that Europa’s crust may be much thinner than 100 km, at least in some places. It seems more and more that Europa is the place to go to look for life, not Mars.

David Cummings December 12, 2013 at 15:58

I think Mars is still a good candidate for evidence of ancient life (as recent developments have shown) but I agree with you Michael Finfer that Europa is more likely to have life right now.

David Cummings December 12, 2013 at 23:52

Dimitri, don’t you mean 250Mya?

250Gya is way back before the big bang.

David Cummings December 13, 2013 at 0:04
Max December 13, 2013 at 0:16

After reading Greenberg’s book, I think Europa is one of the most interesting places in our solar system. Getting a lander and later a submarine down to the surface should be the top priority of every space agency’s science programme. Forget Mars. Unlike that freeze-dried desert next door, Europa could potentially host compley multicellular life!

I’m honestly puzzled by the lack of interest compared to Mars. With a Curiosity-scale effort and power of SLS or Falcon Heavy, NASA should be able to put together very capable mapping and landing missions, the latter maybe even equipped with a melt-probe designed to reach the subsurface ocean.

Michael December 13, 2013 at 1:23

When the crust is recycled or through surface impacts rock and organics must be mixed throughout the icy crust, no need to go far below to the ocean beneath for life to find a habitat. Organics and salts can lower the local melting point of ice to form a medium in which organisms can flourish. To life on Europa these rocks and organics might be like the ‘Black smokers’ of our oceans.

swage December 13, 2013 at 8:30

“if these giant waterspouts are confirmed”
http://www.nature.com/news/hubble-spots-water-spurting-from-europa-1.14357

confirmed

And the same goes for Enceladus. Now there are two extraterrestrial subsurface oceans in the solar system.

We have evidence for material erupting from those oceans, potentially distributing organisms between icy moons in the Jupiter and Saturn systems.

The question now is how much time it takes for the outer crust of these icy moons to be recycled into the interior.

Oh, btw… the samples taken from the plume on Enceladus by Cassini are still with the probe?

Dmitri December 13, 2013 at 9:38

David Cummings, my bad, indeed Mya, not Gya. Thnak you for noting :)

ljk December 13, 2013 at 9:39

Michael said on December 13, 2013 at 1:23:

“When the crust is recycled or through surface impacts rock and organics must be mixed throughout the icy crust, no need to go far below to the ocean beneath for life to find a habitat. Organics and salts can lower the local melting point of ice to form a medium in which organisms can flourish. To life on Europa these rocks and organics might be like the ‘Black smokers’ of our oceans.”

The dark material embedded in all those lines across the icy face of Europa – that is where we need to land some probes. Are they just organic material? Or something more from the ocean depths or even that alien moon’s seafloor?

Freeman Dyson said we should also investigate the space around Europa for the remains of aquatic life forms blasted upward by celestial impacts. Now we can add spraying vents to that possibility.

Dmitri December 13, 2013 at 9:46

I would like to refer to the comments made on this post – http://www.centauri-dreams.org/?p=26749. Most of these “black smokers” have discussed there. I would encourage to listen to Britney Schmidt’s presentation on Europe’s ice crust geological dynamics.

I still wonder what is a normal length for an eon on Europa and would that be sufficient to get accustomed for microbial life forms.

Dmitri December 13, 2013 at 9:56

There is actually no need to confront Mars and other lander missions as there is clear justification why some missions happen more than others. Mars as a geologically dead planet allows to answer fundamental question about origins of (microbial) life. The lack of seasons clearly have opened opportunities to keep the rovers over extended period of time. Before we go to Europa or Titan or Enceladus or wherever place with active geological seasons let’s try an automated rover to cross Arctica / Antartica first. If we manage that we have a solid expertise how to build off planet rovers.

Michael December 13, 2013 at 11:09

ljk said on December 13, 2013 at 9:39

‘The dark material embedded in all those lines across the icy face of Europa – that is where we need to land some probes. Are they just organic material? Or something more from the ocean depths or even that alien moon’s seafloor?’

Organics on the surface of Europa are going to be rare, U.V is high and the high energy radiation around Jupiter will destroy it quite quickly. The orange material is mostly likely sulphur compounds from an ocean but there are organisms that find the compound useful to their metabolism such as Ferroplasma acidiphilum.

http://microbewiki.kenyon.edu/index.php/Ferroplasma

Ferroplasma spp. are acidophilic microorganisms that help accelerate the rate of disintegration of metal sulfide minerals . The oxidative disintegration of Sulfides (primarily pyrite, FeS2) plays an important role in the geochemical sulfur cycle and causes the formation of acid mine drainage (AMD). Ferroplasma helps precipitate the rate of pyrite through regeneration of Fe3+, the primary pyrite oxidant at low pH.

Harry R Ray December 13, 2013 at 11:18

WHAT A DIFFERENCE JUST A FEW DAYS MAKES!I am not commenting on THIS post, but, instead on the INEVITABLE FUTURE POST about the discovery of water vapor erupting from vents at Europa’s south pole! My question is:the Juno spacecraft is designed mainly to explore Jupiter’s clouds and magnetic fields, but,after it has fulfilled that mission, can it’s trajectory be changed to fly REAL LOW,directly over these plumes (like Cassini does at Enceladus) to see if any ice or organic materials are also ejected? Sombody help me here,please!

Harry R Ray December 13, 2013 at 11:28

POSTSCRIPT TO THE ABOVE COMMENT: Why the SOUTH pole (and,apparently just the south pole) for BOTH Europa and Enceladus? Just SOUTH p ols

andy December 13, 2013 at 14:02

To play Devil’s advocate: does the presence of geysers necessarily imply a thin ice crust, or could the reservoir be a lake enclosed within a thick crust as suggested in this model for the origin of Europa’s chaos terrain?

ljk December 13, 2013 at 14:38

Europa: No Longer a “Should,” But a “Must”

Posted by Casey Dreier

2013/12/12 07:51 CST

Topics: Jupiter’s moons, Europa, Space Policy, Future Mission Concepts

Throughout history there are tipping points when the reasons to do something difficult become so compelling that no one can rightfully ignore them – times when we cross the threshold from “should” to “must.”

Today we hit that tipping point for Europa.

This enigmatic moon of Jupiter has long called out to us with its liquid water ocean that is likely in direct contact with hot spots on a rocky core. We’ve all read Arthur C. Clarke’s 2001 sequels – well, not all of us, but for decades both scientists and the public have felt the draw to this enigmatic moon.

Confusingly, missions to explore Europa have languished in conceptual stages, never getting off the ground.

But today’s announcement that the moon’s liquid water ocean is likely spewing forth from large geysers on its surface changes things. Instead of a call for exploration, Europa cries out to us. It’s venting its most habitable environment into space, greatly reducing the complexity needed by spacecraft to analyze its chemistry. Suddenly, we can perform initial scouting for organic molecules in Europa’s oceans without the complexities of having to land and drill. That’s huge.

It is rare that the universe does us a favor. This is something we shouldn’t let pass us by.

NASA, with support from a number key people in Congress, has spent years studying Europa mission concepts. One, the Clipper, was the cover of our 2013 Equinox issue of The Planetary Report. The Clipper flies by Europa something like 45 times in a 3.5-year mission. This minimizes the time spent in the harsh radiation belts of Jupiter and saves a lot of fuel and time by not going into orbit around the moon. It costs half as much ($2.1 billion) as an orbiting mission would have, and would achieve nearly all of the same science.

Full article here:

http://www.planetary.org/blogs/casey-dreier/2013/1212-europa-no-longer-a-should-but-a-must.html

Rob Henry December 13, 2013 at 19:35

Andy – I don’t get it. How are you playing devil’s advocate here? If the geyser comes from below the ice and is driven by superheated steam powerful enough to blast through a deep ocean and to a surface several hundred kilometers above, there is no way that it wouldn’t have melted patch of ice through to the surface also, and it sure ain’t done that. This water would have to be squeezed out from a (thick) crust. Wouldn’t it??

Dmitri – I don’t get your excitement over the ‘thin’ crust either. This would still be tens of kilometers deep, and we already know that its average turnover rate (bringing high energy chemicals from the surface) is in the 10 – 500 million year range. To get really excited we need to find many subsurface lakes with super high turnover of the surface layers above them. To me thick ice scenarios would support that better, with both thick and thin ice models having problems as to how higher forms migrate between lakes.

andy December 14, 2013 at 7:53

@Rob Henry: I was referring to earlier comments that suggested this implies the ice crust must be relatively thin if geysers are present. I have no idea where you are getting your idea that I am talking about something punching its way up all the way through the ocean as well.

Michael December 14, 2013 at 16:49

‘Harry R Ray December 13, 2013 at 11:28

POSTSCRIPT TO THE ABOVE COMMENT: Why the SOUTH pole (and,apparently just the south pole) for BOTH Europa and Enceladus? Just SOUTH p ols’

Just having a thought about this possible South pole Geyser.

When a moon is flexed, the equator region would tend to close cracks at the ocean/ice crust interface and open cracks on the surface. This could help limit liquid moving up through to the surface. Where as at the polar regions the flexing would want to open cracks at the ocean/ice interface and close cracks at the surface allowing liquid to move upwards.

Just a thought

Michael December 14, 2013 at 16:52
Rob Henry December 14, 2013 at 19:55

Andy, I realized you couldn’t be thinking of that, but here is what puzzled me…

If you are playing devil’s advocate, it implies that you know of some good mechanism whereby those geysers imply a thin crust. My problem is that my imagination can’t stretch enough to find any good one (so I gave a bad one). Yours seems to have, and I was keen to find what it was. On the other hand perhaps you can’t either then it was just your use of the phrase ‘devil’s advocate’ that confused me.

PS. I note that supporting the pressure of a geyser would normally require that there is a large are of very high tensile material that can hold pressure somewhere. I was thinking of how we could avoid that implying a thick crust.

ljk December 16, 2013 at 10:37

Europa Erupts: Hubble Space Telescope Discovers Tantalising Evidence Of Water Plumes On Jupiter’s Moon

By Leonidas Papadopoulos

“All these worlds are yours, except Europa.
Attempt no landing there.”

– 2010: The Year We Make Contact

In the fictional universe of 2010, people on Earth receive a message being described as the most important one ever transmitted, concerning the presence of life on Europa. In the real world, scientists have possibly discovered the most important evidence to date, for the presence of a liquid water ocean underground this fascinating Jovian moon.

This year has turned out to be a really good one for planetary science, with important and fascinating discoveries concerning the possible habitability of various places in the Solar System. Just days after we have reported here on AmericaSpace on new evidence from the Mars Reconnaissance Orbiter, about current flowing water on the Red Planet and new discoveries of phylosilicates on Europa, the Jovian moon has once again come to the spotlight. Scientists working with the Hubble Space Telescope, announced the results of their observations of water plumes on Europa’s surface.

The new Hubble observations were reported at a press conference during the recent 2013 Fall meeting of the American Geophysical Union, held at San Francisco, Cal, between 9-13 December. A scientific team led by Lorenz Roth of the Southwest Research Institute in San Antonio, Texas, used Hubble’s Space Telescope Imaging Spectrograph or STIS, to conduct observations of Europa in ultra-violet wavelengths, during November and December of 2012.

The team was particularly interested to confirm the presence of water vapors coming from Europa, that were hinted at by previous observations from Hubble in 2009. During their 2012 observing campaign, the scientists discovered a vast amount of hydrogen and oxygen ions, coming from the moon’s south polar region.

A set of observations made by Hubble in the ultraviolet, in December 2012, when Europa was at the apocenter of its orbit around Jupiter. At left, the hydrogen ion signature near Europa’s south pole, and at right, the oxygen ion signature. The red circles point to the ion signatures and white cirlce shows the position of Europa. Image used from the team’s presentation at the recent AGU meeting.

“With these images, we were able to detect water vapor in Europa’s south pole, for the first time”, says Kurt D. Retherford, co-author of the study, also of the Southwest Research Institute in San Antonio. “These images point to the existence of water vapor, about 200-km high, at or near the south pole of Europa”.

Full article here:

http://www.americaspace.com/?p=46831

andy December 16, 2013 at 11:37

@Rob Henry: I’m playing devil’s advocate because I don’t necessarily hold the position that the ice crust must be thick. I’d much prefer a thin ice scenario, for starters thick ice would make getting a mission into the ocean even more of a devilishly challenging task… ;)

ljk December 18, 2013 at 15:45

Earth and Mars may have “contaminated” Europa and other places long before humans came along with their germy little space probes:

http://www.americaspace.com/?p=46630

Mundus Gubernavi December 22, 2013 at 20:13

I had linked to the very same JPL news release (http://www.centauri-dreams.org/?p=29680#comments) without noticing this previous post. Hard to keep up with the discussions when the material is pretty much dealing with the same issues and all lead in the same direction. My mistake lol

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