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Enceladus "Sea" Mystery Deepens
Smivs writes "The BBC reports that an ocean may not be the source of the jets emanating from Saturn's moon Enceladus. Controversial research questions the moon's promise as a target in the search for life beyond Earth. A chemical analysis of Enceladus, led by University of Colorado planetary scientist Nick Schneider, failed to detect sodium, an element scientists say should be present in any body of water that has been in contact with rock for billions of years. Spectral analysis with the Keck Telescope found no sodium in the plumes or in the vapor in orbit around the moon. At stake is whether Saturn's moon could support alien life and is thus a worthy target for a NASA exploratory mission to detect it. Such a mission to Enceladus is one of four currently under review for further development."
...overmining by the Europans. Yes, the sole hyperpower in far solar orbit is exploiting the resources of honest, hard-working, frozen Enceladans. Don't buy Morton Salt.
Don't trust anyone under thirty.
Isn't Lake Michigan, along with all the other lakes, refilled every so often (on a geological time scale)? Seems to me that any salt that eroded from the rocks would eventually flow downstream and end up in the oceans. And it would get filled up again by rain water, which doesn't contain salt. That is my completely made up reason as to why lakes don't have salt, while oceans and seas do. Anybody know whether or not it makes any sense.
Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.
Sodium existing as a requirement for life is not the issue here. I know this is slashdot and everything, but even TFS clearly states that the question is whether or not an ocean is the source of the water plumes that have been observed. It is the ocean we are looking for and it is the ocean that we believe is an indication of possible life.
You may still take offense to the assumption that water is required, but when millions, nay, billions of dollars are on the line at NASA, you can be sure that greater and brighter minds than you or I have taken all the considerations and the great majority of scientists continue to believe that large bodies of liquid water are sufficient if not necessary conditions for life.
Furthermore, if there is life, but not as we know it, then it is nigh unto impossible for us to begin looking for it. The most resources must necessarily be used in a manner which has the highest chance for success, and the small odds of finding life as we know it still compare favorably to the negligible odds that we find life as we do not.
Although a lack of salt is a fine excuse to not send a mission here, the better reason is that these missions are a tremendous waste of taxpayer resources. While I am no free market capitalist, it is waste like this which give fire to those who say that government can't make financially sound decisions. Lets focus our space program on useful tasks such as orbital solar energy collection and leave the fruitless search for extraterrestrial life to the hobbiests.
Indeed ! Some tests are done more often then others.
Solubility of sodium chloride (or calcium chloride) in water is commonly used to prevent it from freezing (application - cleaning sidewalks).
The mixture of salt and water freezes at -21 Celsius = 272K or sooner, depending on purity. When salt water freezes it separates the salt which is why Antartic ice is not salty.
From Wikipedia, the surface temperature of Enceladus is at most 145K, so it is likely that surface ice is pure and it is possible that the liquid water is kept liquid by tidal forces (water in motion freezes at lower temperature). One can even imagine how period crystallization and melting of water by tidal forces has separated out salt somehow.
That said, sodium is extremely easy to ionize. To see that put a few salt crystals into gas or alcohol flame - it will turn yellow from the small quantity of sodium atoms that evaporated from the crystals. Thus, if liquid water was in direct contact with rock it would contain trace amounts of sodium which, when launched into space with the jet, will provide pronounced yellow line.
What is possibly happening is that two ice sheets (pure H20) collide, melt ice with the pressure and spray the resulting water into space. TFA mentions two more possibilities - as well as a speculation that Sodium atoms could be frozen inside water crystals.