APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

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APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by APOD Robot » Fri Apr 01, 2016 4:13 am

Image Europa: Discover Life Under the Ice

Explanation: Looking for an interplanetary vacation destination? Consider a visit to Europa, one of the Solar System's most tantalizing moons. Ice-covered Europa follows an elliptical path in its 85 hour orbit around our ruling gas giant Jupiter. Heat generated from strong tidal flexing by Jupiter's gravity keeps Europa's salty subsurface ocean liquid all year round. That also means even in the absence of sunlight Europa has energy that could support simple life forms. Unfortunately, it is currently not possible to make reservations at restaurants on Europa, where you might enjoy a dish of the local extreme shrimp. But you can always choose another destination from Visions of the Future.

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Guest

Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by Guest » Fri Apr 01, 2016 10:22 am

But wouldn't there be enough radiation, even under the ice, to be lethal to humans?

Joe25

Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by Joe25 » Fri Apr 01, 2016 11:17 am

The film "The Europa Report" has something to say about what you'll find 'under the ice' ! lol
As to the restaurants on Europa, their atmosphere is rather heavy, unlike the restaurants on our Moon, which didn't do very well because they had no 'atmosphere' !

gvann

Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by gvann » Fri Apr 01, 2016 1:14 pm

"Europa follows an elliptical path". I didn't think so.

I remember reading an article in Science magazine in February, 1979, about one week before the arrival of Voyager 1 at Jupiter. From what I remember of the article, the authors noted that the orbits of the Galilean satellites have virtually no eccentricity. However, because they are locked in mutual resonance, the gravitational interaction between the satellites causes an "effective" eccentricity whereby the tidal deformation induced by Jupiter varies with time.

The article went on to calculate the amount of energy dissipated in the satellite Io as a result of such varying tidal deformation. It concluded that the dissipated energy was large enough that volcanism might occur extensively on Io.

A week later Voyager 1 discovered Io's volcanoes.

From what I understand, the same happens with Europa: The orbit has no eccentricity, but the gravitational interaction with the other satellites causes Europa to experience variations in the tidal deformation induced by Jupiter. The associated energy is much less than for Io, and is not sufficient to cause volcanic activity; but it's sufficient to keep a large fraction of Europa's water in a liquid state, and provides a steady internal source of energy.

The liquid water on Europa lies under a layer of ice 10-30 km thick. Even with Europa's weak gravity, compared to Earth, pressure under that layer is going to be quite large. Hence the comment by Joe25 about the atmosphere being heavy at the Europa restaurant.

The ice layer blocks radiation very effectively. I am guessing that the bulk of radiation in Europa's subsurface ocean is due to solar and cosmic neutrinos. I wouldn't worry much about it.

Skyfire

Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by Skyfire » Fri Apr 01, 2016 1:45 pm

All these worlds are yours, except Europa. Attempt no landing there. Use them together. Use them in peace.

banderso

Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by banderso » Fri Apr 01, 2016 1:46 pm

All these worlds are yours - except Europa. Attempt no landing there. - Arthur C. Clarke: 2010

heehaw

Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by heehaw » Fri Apr 01, 2016 2:11 pm

I was shocked to the core when I went to today's ESPOD : http://epod.usra.edu/blog/ Click on the picture to get the high resolution. I hope this is not some stupid April Fool joke?

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Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by Asterhole » Fri Apr 01, 2016 2:31 pm

Hm - by just reading the title from the Archives list I was hoping to see something other than some cheesy art-deco-ish fake travel poster? Ah, well it is after all April Fools Day here in the States.

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Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by Chris Peterson » Fri Apr 01, 2016 2:33 pm

gvann wrote:"Europa follows an elliptical path". I didn't think so.
Of course, this is poor wording in the caption. Every two-body closed orbit is elliptical. More properly, the path should have been identified as eccentric. And while the eccentricity of Europa's orbit is low, it is probably sufficient to generate enough tidal heating to keep the interior ice melted. The effect of resonance with Io isn't significant additional flexure, but rather, it serves to maintain a degree of eccentricity- otherwise, the orbit would be truly circular.
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Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by neufer » Fri Apr 01, 2016 3:43 pm

[img3="Europa's low eccentricity in conjunction with Io's close passages
make Io's "flexures" on Europa about 2.7 times that due to Jupiter.
(Ganymede's "flexures" on Europa are only ~77% that due to Jupiter.)
"]https://upload.wikimedia.org/wikipedia/ ... mation.gif[/img3]
Chris Peterson wrote:
gvann wrote:
"Europa follows an elliptical path".
I didn't think so.
Of course, this is poor wording in the caption. Every two-body closed orbit is elliptical. More properly, the path should have been identified as eccentric. And while the eccentricity of Europa's orbit is low, it is probably sufficient to generate enough tidal heating to keep the interior ice melted. The effect of resonance with Io isn't significant additional flexure, but rather, it serves to maintain a degree of eccentricity- otherwise, the orbit would be truly circular.
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Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by neufer » Fri Apr 01, 2016 3:53 pm

Guest wrote:
But wouldn't there be enough radiation, even under the ice, to be lethal to humans?
https://en.wikipedia.org/wiki/Colonization_of_Europa wrote:
<<The colonization of Europa presents numerous difficulties. One is the high level of radiation from Jupiter's radiation belt, which is about 10 times as strong as Earth's Van Allen radiation belts. As Europa receives 540 rem of radiation per day, a human would not survive at or near the surface of Europa for long without significant radiation shielding. Colonists on Europa would have to descend beneath the surface when Europa is not protected by Jupiter's magnetotail, and stay in subsurface habitats. This would allow colonists to use Europa's ice sheet to shield themselves from radiation.

In 1997, the Artemis Project produced a plan to colonize Europa. According to this plan, explorers would first establish a small base on the surface. From there, they would drill down into the Europan ice crust, entering the postulated subsurface ocean. The colonists would then create (or, possibly, find) a pocket between the icy surface and the liquid interior in which to establish a base. This location would be protected from radiation by the ice overhead, and would be at a more human-suitable temperature than the surface, as indicated by the presence of liquid water.>>
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Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by Fred the Cat » Fri Apr 01, 2016 4:01 pm

Do you suppose the Europans would be subject to The Jupiter Effect?
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Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by Chris Peterson » Fri Apr 01, 2016 4:23 pm

neufer wrote:Europa's low eccentricity in conjunction with Io's close passages make Io's "flexures" on Europa about 2.7 times that due to Jupiter.
Interesting. I wouldn't have thought the the tidal force would be that significant from Io.

That said, I do recall an analysis demonstrating that the tidal heating from Jupiter alone (given the eccentricity of Europa's orbit) is sufficient to explain interior oceans.
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Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by neufer » Fri Apr 01, 2016 5:45 pm

Chris Peterson wrote:
neufer wrote:
Europa's low eccentricity in conjunction with Io's close passages make Io's "flexures" on Europa about 2.7 times that due to Jupiter.
Interesting. I wouldn't have thought the the tidal force would be that significant from Io.

That said, I do recall an analysis demonstrating that the tidal heating from Jupiter alone (given the eccentricity of Europa's orbit) is sufficient to explain interior oceans.
OOPS :!: My bad....

I underestimated Jupiter's "flexures" by a factor of 500 :oops: (Senility?)

(Tidal heating will also depend upon the rate of flexure but Jupiter dominates for sure.)
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Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by Cousin Ricky » Fri Apr 01, 2016 6:04 pm

heehaw wrote:I was shocked to the core when I went to today's ESPOD : http://epod.usra.edu/blog/ Click on the picture to get the high resolution. I hope this is not some stupid April Fool joke?
Do you really have to ask?

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Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by geckzilla » Fri Apr 01, 2016 8:15 pm

Cousin Ricky wrote:
heehaw wrote:I was shocked to the core when I went to today's ESPOD : http://epod.usra.edu/blog/ Click on the picture to get the high resolution. I hope this is not some stupid April Fool joke?
Do you really have to ask?
That was a spin-off from the Saturn/ISS debacle earlier this year. You can partially thank Julian Wessel for it. ;)
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jouster

Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by jouster » Fri Apr 01, 2016 8:55 pm

These are very high resolution images as well as beautiful. I saved some of the JPL Visions of the Future images to a flash drive and went to CostCo. For 10 bucks each I had very high quality 20 x 30 inch prints made. A stop at the Craft store found 20x30" frames on sale for $18. My walls look much better now.

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Re: APOD: Europa: Discover Life Under the Ice (2016 Apr 01)

Post by Boomer12k » Fri Apr 01, 2016 11:33 pm

Why go down that far? You can just get water by melting it, and shipping it... plus you would be polluting another place in the solar system... going to need some heavy cabling, and heat to go down that far, PLUS...

But then Jupiter's Magnetosphere is hazardous, as it is many, many times stronger than our own...

"In 2003, NASA conducted a conceptual study called "Human Outer Planets Exploration" (HOPE) regarding the future human exploration of the outer solar system. The possibility was mooted of building a surface base on Callisto, because of the low radiation levels at the moon's distance from Jupiter and its geological stability. Callisto is the only one of Jupiter's Galilean satellites for which human exploration is feasible. The levels of ionizing radiation on Io, Europa and Ganymede are inimical to human life, and adequate protective measures have yet to be devised."

From Wikipedia...

I am willing to go to the restaurant on Callisto... and have a tall one with Jandar...

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