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Tuckerfan
2007-Dec-17, 12:46 AM
Sodium not detected, looks bad for an ocean under that ice. (http://news.bbc.co.uk/1/hi/sci/tech/7145530.stm)
An ocean is not the source of the jets emanating from Saturn's moon Enceladus, a new study concludes.

The research questions the moon's promise as a target in the search for life beyond Earth and has stirred controversy among scientists who dispute its conclusions.

A chemical analysis of Enceladus, led by University of Colorado planetary scientist Nick Schneider, failed to detect sodium, an element scientists say should be in a body of water that has had billions of years of contact with rock.NASA's still considering sending a dedicated mission to Enceladus, but I think that it shouldn't come before a mission to Europa. That still has the best possibility of an ocean under all the ice (and thus life).

GOURDHEAD
2007-Dec-17, 03:50 PM
The ice shell around Europa should be opened only with great caution. I suspect Pandora's box on steroids. Still, I'm all for opening the box and those of Ganymede and Callisto as well.

Justanotherrandomguy
2007-Dec-17, 04:01 PM
All these worlds are yours, except Europa, attempt no landings there.

RGClark
2007-Dec-17, 06:49 PM
Can not fresh water lakes be long lived?

Bob Clark

Noclevername
2007-Dec-17, 08:53 PM
Can not fresh water lakes be long lived?


Not compared to an ocean. But the sodium expectation is based on the assumption of liquid water in direct contact with the rock-- a thick layer of ice (or some other substance) at the ocean bottom might prevent this. Arctic and Antarctic seas on Earth sometimes develop ice on the bottom, I believe, so it's possible.

JonClarke
2007-Dec-17, 09:48 PM
Can not fresh water lakes be long lived?

Lakes are open systems with respect to salts, oceans much less so. In fact you have to actively remove salts from the oceans otherwise the oceans would be like the Dead Sea, a supersaturated brine.

Jon

tusenfem
2007-Dec-19, 08:00 AM
Okay, now we are mixing Enceladus and Europa. To return to the OP, there are a few papers trying to explain what is happening at Enceladus.

In GRL there is this paper (http://www.agu.org/pubs/crossref/2007/2007GL031234.shtml) about why salt may not come out even though it is there.

And in Physics Today of October 2007, there was this paper (http://ptonline.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PHTOAD000060000010000042000001&idtype=cvips&gifs=Yes) about Clathrate Hydrates Under Pressure, which might have something to do with Enceladus' plume.

Noclevername
2007-Dec-19, 08:18 AM
Okay, now we are mixing Enceladus and Europa. .

Europa was mentioned in the OP. It relates to the topic of where to send a probe.

tusenfem
2007-Dec-19, 10:23 AM
Europa was mentioned in the OP. It relates to the topic of where to send a probe.

You are right! Bad case of quick reading :-)

ESA is planning a 2 spacecraft mission called LaPlace that will send a mother orbiter to Jupiter and a daughter orbiter around Europa. At the moment no landers are planned but who knows what might happen between now and 2019.

vk3ukf
2007-Dec-23, 01:29 PM
If Enceladus has an extremely thick crust of ices, and tidal forces cause warming just below the surface, then a subsurface ocean or lakes with an ice floor and an ice roof may exist.
A journey to the centre of Enceladus,
A crust of 0.5 to 1 or 2 km thick, several km of liquid, several hundred km of solid ices, then the rocky core.
Although reality will probably be just outright bizarre.
There has been an assumption that immediately below the ocean and in contact with it are salt bearing rocks.
Maybe there is no ocean or lakes at all.
Perhaps the fluids are ejected and squeezed out as soon as liquid is formed in the fissures and cracks. With nothing more than a few underground creeks and rivers.

??

Is Callisto not a target for investigation?
There is a huge scar on Callisto, which (to me anyway), says,
"Hi, I have a thick icy crust and a liquid ocean below, see where a big asteroid hit me, I swallowed it up, and healed my injury."

If someone could enlighten me as to the features name, I would be grateful.

See this link,
http://www.planetary.org/blog/article/00001264/

from this discussion,
http://www.bautforum.com/space-exploration/68234-new-views-galileo.html

or just look at the pic on the Planetary Society site.

http://www.planetary.org/image/callisto_e11.jpg


Credit: NASA / JPL / Ted Stryk

Not sure if it was the right thing to post that link to the image on the Planetary Society website, perhaps I should have copied the pic, put it on my own site, then linked to it. You know, some folks protect their bandwidth.
Kev.

KaiYeves
2007-Dec-23, 06:37 PM
And no soup for you! ;-)

Zachary
2008-Jan-02, 03:44 PM
You are right! Bad case of quick reading :-)

ESA is planning a 2 spacecraft mission called LaPlace that will send a mother orbiter to Jupiter and a daughter orbiter around Europa. At the moment no landers are planned but who knows what might happen between now and 2019.

Laplace, not LaPlace ;), named after a famous french mathematician if I'm not mistaken.

tusenfem
2008-Jan-07, 01:36 PM
Laplace, not LaPlace ;), named after a famous french mathematician if I'm not mistaken.

You are right Zach, and as a member of the Laplace team I should have know how to spell it!