APOD: The Surface of Europa (2016 May 19)

[APOD Robot]

The Surface of Europa

Explanation: An enhanced-color view, this image covers a 350 by 750 kilometer swath across the surface of Jupiter's tantalizing moon Europa. The close-up combines high-resolution image data with lower resolution color data from observations made in 1998 by the Galileo spacecraft. Smooth ice plains, long fractures, and jumbled blocks of chaos terrain are thought to hide a deep ocean of salty liquid water beneath. Though the ice-covered alien ocean world is outside the Solar System's habitable zone, new studies show the potential chemistry driving its oxygen and hydrogen production, a key indicator of the energy available for life, could produce amounts comparable in scale to planet Earth. Hydrogen would be generated by chemical reactions of the salty water in contact with the rocky ocean floor. Oxygen and other compounds that react with hydrogen would come from Europa's surface. There water ice molecules would be split apart by the intense flux of high-energy radiation from Jupiter and cycled into the Europan ocean from above.

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[Ann]

Europa is fascinating, that's for sure. I would love to see this strange moon being explored by man-made orbiters.

Even better might be a lander. But I think those long well-ordered-looking ridges are really terrible cliffs close up. Landing on Europa might be dangerous.

But Juno is on its way to Europa, isn't it? Learning more about Jupiter and its moons should be (and is, I think) a high priority for NASA.

Ann

[geckzilla]

I don't think Juno will be studying Jupiter's moons much. Last I looked at its science objectives, the moons weren't included. It's also got a visible light camera that will operate for 7 orbits before the planet itself kills it. It doesn't sound like it'll be Jupiter's version of Cassini, if that's what you were hoping for.

[Mike A]

What do you mean "outside the habitable zone"? Look at all the freeways!

[Coil_Smoke]

Looks Like someone knocked the cover off a baseball ...

[RafaC]

Turn the image upside down and all the ridges become crevasses and the mounds, depressions. I wonder which is the true view.

[Guest]

Oxygen and other compounds that react with hydrogen would come from Europa's surface. There water ice molecules would be split apart by the intense flux of high-energy radiation from Jupiter and cycled into the Europan ocean from above.

Does this hint that hydrogen and oxygen would recombine to form 'water rain' that falls onto the surface to be 'cycled into the Europan ocean from above', or some form of precipitated condensate (ice crystals?) that float down. If the later, would we not be able to see drift patterns across the rills/valleys or fracture/pressure ridges on the surface?

[ygmarchi]

Amazing wallpaper

[Tonnegl]

I don't get it. Why is there an "intense flux of high-energy radiation from Jupiter" ??

[Chris Peterson]

I don't get it. Why is there an "intense flux of high-energy radiation from Jupiter" ??

Technically, it's not from Jupiter itself but from the intense radiation belts that surround Jupiter- a consequence of the interaction of Jupiter's strong magnetic field with the local space environment.

[neufer]

[b][color=#0000FF][size=150]Juno's elliptical orbit and the Jovian radiation belts[/size][/color][/b]

---

I don't get it. Why is there an "intense flux of high-energy radiation from Jupiter" ??

• Jovian radiation (Van Allen) belts

<<As cold, dense plasma moves outward, it is replaced by hot, low-density plasma (temperature 200 million K (20 keV) or higher) moving from the outer magnetosphere. This plasma, adiabatically heated as it approaches Jupiter, forms the radiation belts in Jupiter's inner magnetosphere.>>

[NRCarlson9721]

Turn the image upside down and all the ridges become crevasses and the mounds, depressions. I wonder which is the true view.

Agreed; I'm guessing those are crevasses and depressions. Very narrow ridges like those would seem much less stable than narrow crevasses. It would be really surprising to me if they are ridges, but then these moons are constantly surprising me.

[Asterhole]

Turn the image upside down and all the ridges become crevasses and the mounds, depressions. I wonder which is the true view.

Agreed; I'm guessing those are crevasses and depressions. Very narrow ridges like those would seem much less stable than narrow crevasses. It would be really surprising to me if they are ridges, but then these moons are constantly surprising me.

I see them as ridges with a depressed fault line running through the middle, and here's why. Look at the enlarged view and near the center about 10 o'clock there is a very small impact crater surrounded by a dark ejecta field. This to me puts the image into perspective.

[bystander]

Europa's Ocean May Have An Earthlike Chemical Balance
NASA | JPL-Caltech | AGU | 2016 May 17

A new NASA study modeling conditions in the ocean of Jupiter's moon Europa suggests that the necessary balance of chemical energy for life could exist there, even if the moon lacks volcanic hydrothermal activity.

Europa is strongly believed to hide a deep ocean of salty liquid water beneath its icy shell. Whether the Jovian moon has the raw materials and chemical energy in the right proportions to support biology is a topic of intense scientific interest. The answer may hinge on whether Europa has environments where chemicals are matched in the right proportions to power biological processes. Life on Earth exploits such niches. ...

Geophysical Controls of Chemical Disequilibria in Europa - Steven D. Vance, Kevin P. Hand, R. T. Pappalardo

• Geophysical Research Letters (online 17 May 2016) DOI: 10.1002/2016GL068547

[neufer]

---

<<Dr. Unger (Embeth Davidtz), CEO of Europa Ventures, narrates the story of the Europa One mission. Six astronauts embark on a privately funded mission to Europa, a moon of Jupiter, to find potential sources of life.

The ship lands safely, but misses its original target zone. The crew drills through the ice and releases a probe into the underlying sea. Blok, who is sleep-deprived and eliciting concern in the rest of the crew, sees a light outside the ship. However, he is unable to record it or otherwise convince the crew of its occurrence. The probe is struck by an unknown lighted object, and contact with it is lost.

Petrovna insists on collecting samples on Europa's surface. After a crew vote, she embarks on a walk outside. Analyzing the samples, Luxembourg discovers traces of a single-celled organism. As communication is disrupted by increasing radiation, Petrovna sees a blue light in the distance; she decides to investigate it. She approaches the light glowing through the ice; the ice below her breaks and she falls through. As she descends into the depths, only her head camera continues to show footage, displaying her terrified face as the blue bioluminescence is reflected in her eyes, before cutting out.

The crew agrees to leave in order to bring their discovery back to Earth, but the engines malfunction. As the ship hurtles back to Europa's surface, Xu unbuckles from his seat to remove water shielding to reduce the impact speed. Remarkably, the ship crashes at the originally-targeted landing site. On impact, Xu is killed, and the ship is damaged, leaking oxygen and losing heat. It begins to sink into the ice.

Blok and Luxembourg suit up to make repairs outside the ship. Luxembourg tries to descend, but falls through the ice. Blok knows that there is no chance that he alone will be able to repair the ship before it sinks. Instead, he manages to fix the communication system, at the expense of turning off the life support systems, just before the same blue light Petrovna saw approaches and he appears to fall through the ice as well.

Dasque re-establishes communication with Earth. All the collected images and data that have been saved over the blackout months are sent, just as the ice cracks and the ship begins to sink. Alone and anticipating her death, Dasque opens the airlock to flood the ship in hopes of revealing the source of the light. As the water rises to the cockpit, she sees a tentacled, bioluminescent creature rising toward her, before the camera cuts out.

In the epilogue, Unger confirms that the crew of Europa had discovered life, and exceeded every expectation, as the footage plays from an earlier scene of the crew posing in front of the camera.>>

[BMAONE23]

definitely a place that I would like to see a Curiosity style rover examining

[heehaw]

Turn the image upside down and all the ridges become crevasses and the mounds, depressions. I wonder which is the true view.

Wikipedia: Europa's most striking surface features are a series of dark streaks crisscrossing the entire globe, called lineae (English: lines). Close examination shows that the edges of Europa's crust on either side of the cracks have moved relative to each other. The larger bands are more than 20 km (12 mi) across, often with dark, diffuse outer edges, regular striations, and a central band of lighter material.[42] The most likely hypothesis states that the lineae on Europa may have been produced by a series of eruptions of warm ice as the Europan crust spread open to expose warmer layers beneath.[43] The effect would have been similar to that seen in Earth's oceanic ridges. These various fractures are thought to have been caused in large part by the tidal flexing exerted by Jupiter. Because Europa is tidally locked to Jupiter, and therefore always maintains the same approximate orientation towards Jupiter, the stress patterns should form a distinctive and predictable pattern. However, only the youngest of Europa's fractures conform to the predicted pattern; other fractures appear to occur at increasingly different orientations the older they are. This could be explained if Europa's surface rotates slightly faster than its interior, an effect that is possible due to the subsurface ocean mechanically decoupling Europa's surface from its rocky mantle and the effects of Jupiter's gravity tugging on Europa's outer ice crust.[44] Comparisons of Voyager and Galileo spacecraft photos serve to put an upper limit on this hypothetical slippage. The full revolution of the outer rigid shell relative to the interior of Europa occurs over a minimum of 12,000 years.[45] Studies of Voyager and Galileo images have revealed evidence of subduction on Europa's surface, suggesting that, just as the cracks are analogous to ocean ridges,[46][47] so plates of icy crust analogous to tectonic plates on Earth are recycled into the molten interior. Together, the evidence for crustal spreading at bands[46] and convergence at other sites[47] marks the first evidence for plate tectonics on any world other than Earth. [14]

[Cousin Ricky]

When I look at the closeup, the dark areas look like cast shadows, with uneven edges toward the bottom. This leads me to believe that the scene is illuminated from the top, and that the linear features are double ridges.

[Ann]

Petrovna sees a blue light in the distance; she decides to investigate it. She approaches the light glowing through the ice; the ice below her breaks and she falls through. As she descends into the depths, only her head camera continues to show footage, displaying her terrified face as the blue bioluminescence is reflected in her eyes, before cutting out.

Killed by blue bioluminescence, being a part of the crew that sacrificed their lives to prove the existence of glowing blue life forms on Europa.

It could be worse.

Ann

[Quantum Tango]

This reminds me of the canals on Mars from the 19th century. Blatantly ignoring the fact that Europa is outside of the hospitable zone, I had to ask myself: What does this look like?
A highway system! It looks like a lot of roads in an urban area! I know, that's ridiculous, but just take a step back, and look, don't judge.

[geckzilla]

A highway system! It looks like a lot of roads in an urban area! I know, that's ridiculous, but just take a step back, and look, don't judge.

Not that ridiculous. There are a lot of things in nature with the sort of geometry reminiscent of our road infrastructure. The vascular systems of animals also comes to mind.

[highschool dropout]

Jovian moon Europa definitely is a water ice covered body: it is apparent that beneath the ice is an ocean of water which is churning in sulphur-rich compounds as evidenced by the yellowish color of flow issuing from cracks in crust. Europa is likely to have bioforma which thrive in sulphur-rich salty brine similar to geologically active regions of the Earth. However, these probably would not be of zoological or economic importance. It would be unwise to devise a mission to Europa to bring such bioforma to the Earth if they existed. Still, sending an astronaut to Europa would be nice if only to take a selfie with Jupiter in the background. Personally, I would prefer a mission to Triton, the doomed moon of Neptune. Ofcourse, there is a means for preventing Triton's eventual catastrophic plunge into Neptune. However, the technology to effect such corrections do not exist on Earth. But, it does exist.

[Chris Peterson]

Jovian moon Europa definitely is a water ice covered body: it is apparent that beneath the ice is an ocean of water which is churning in sulphur-rich compounds as evidenced by the yellowish color of flow issuing from cracks in crust. Europa is likely to have bioforma which thrive in sulphur-rich salty brine similar to geologically active regions of the Earth.

It is a huge leap from the possible existence of some conditions with the potential to support life to an assumption of the actual presence of life.

[neufer]

Jovian moon Europa definitely is a water ice covered body: it is apparent that beneath the ice is an ocean of water which is churning in sulphur-rich compounds as evidenced by the yellowish color of flow issuing from cracks in crust. Europa is likely to have bioforma which thrive in sulphur-rich salty brine similar to geologically active regions of the Earth. However, these probably would not be of zoological or economic importance.

• They would definitely be of zoological importance.

<<Since the Voyager spacecraft flew past Europa in 1979, scientists have worked to understand the composition of the reddish-brown material that coats fractures and other geologically youthful features on Europa's surface. Spectrographic evidence suggests that the dark, reddish streaks and features on Europa's surface may be rich in salts such as magnesium sulfate, deposited by evaporating water that emerged from within. Sulfuric acid hydrate is another possible explanation for the contaminant observed spectroscopically. In either case, because these materials are colorless or white when pure, some other material must also be present to account for the reddish color, and sulfur compounds are suspected.>>

<<Sulfur is an essential component of all living cells. It is the seventh or eighth most abundant element in the human body by weight, about equal in abundance to potassium, and slightly greater than sodium and chlorine. A 70 kg human body contains about 140 grams of sulfur. In plants and animals, the amino acids cysteine and methionine contain most of the sulfur, and the element is present in all polypeptides, proteins, and enzymes that contain these amino acids. In humans, methionine is an essential amino acid that must be ingested. Disulfide bonds (S-S bonds) between cysteine residues in peptide chains are very important in protein assembly and structure. These covalent bonds between peptide chains confer extra toughness and rigidity. For example, the high strength of feathers and hair is due in part to the high content of S-S bonds with cysteine and sulfur. Eggs are high in sulfur to nourish feather formation in chicks, and the characteristic odor of rotting eggs is due to hydrogen sulfide. The high disulfide bond content of hair and feathers contributes to their indigestibility and to their characteristic disagreeable odor when burned.>>

It would be unwise to devise a mission to Europa to bring such bio-forma to the Earth if they existed. Still, sending an astronaut to Europa would be nice if only to take a selfie with Jupiter in the background. Personally, I would prefer a mission to Triton, the doomed moon of Neptune. Of course, there is a means for preventing Triton's eventual catastrophic plunge into Neptune. However, the technology to effect such corrections do not exist on Earth. But, it does exist.

• Plenty of time before we need to be concerned with that:

<<Tidal interactions also cause Triton's orbit, which is already closer to Neptune than the Moon's is to Earth, to gradually decay further; predictions are that 3.6 billion years from now, Triton will pass within Neptune's Roche limit. This will result in either a collision with Neptune's atmosphere or the breakup of Triton, forming a ring system similar to that found around Saturn.>>

[Cousin Ricky]

• They would definitely be of zoological importance.

Unless we redefine “animal” to include extraterrestrial clades with phylogenies similar to those of Metazoa, a better expression would be “biological importance.”