NH3 in Enceladus' water reservoir !

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This is important, because water / ammonia mixtures have very low freezing points. I look forward to the journal article. Nice to see Wired.com is continuing to feature astronomy articles.

Antifreeze Could Keep Saturn Moon Wet
By Hadley Leggett July 22, 2009 | 1:39 pm | Categories: Space
http://www.wired.com/wiredscience/2009/ ... usammonia/

Ammonia, best known on Earth as a potent antifreeze, has been found on Enceladus, offering strong evidence that an ocean of liquid water might be lurking beneath the crust of Saturn’s icy moon.

Jets of ice from cracks near the south pole of Enceladus generate plumes of gas and particles, mostly made of water and carbon dioxide. Last October, using a special instrument on NASA’s Cassini probe, researchers detected traces of ammonia in the plumes, suggesting that the source of the gas might be liquid water beneath the ice shell.

“This is the first time Cassini has actually been able to ’smell’ ammonia,” said planetary scientist Jonathan Lunine of the University of Arizona, co-author of the study in Nature on Wednesday. “And because ammonia is an antifreeze, it probably ensures that there is liquid water in the interior of Enceladus.”

And where there’s water, there could be life. Scientific evidence for liquid water has been piling up in the past year. In June, another paper in Nature reported sodium salts found in Saturn’s outermost ring. Together, these two pieces of data offer a strong argument for liquid water, Lunine said.

“I’m pretty convinced,” Lunine said. “By itself, the findings we have are strong. But they’re made even stronger by the article in Nature last month that found, using a different instrument on Cassini, that there are sodium and ice particles on the E-ring.”

But not everyone is convinced the discovery of ammonia means liquid water on Enceladus. Space scientist Susan Kieffer of the University of Illinois has developed a model that doesn’t require liquid water for the creation of gas plumes, and the finding of ammonia hasn’t changed her skepticism.

“The argument in this paper hinges on an early announcement by NASA that temperatures in excess of 180 Kelvin have been reported,” Kieffer wrote in an e-mail. However, later measurements near the plume cracks reported temperatures closer to 167 Kelvin, she said.

“It sounds like a small difference, but it’s huge in terms of the ammonia-water system,” Kieffer wrote. If the temperature is above 173 Kelvin, there can be liquid water, but below there would likely be a system of frozen solids.

Despite the lower temperatures, Lunine says he stands by his group’s conclusions. Because the Cassini temperature instrument samples a fairly large region around the gas plumes, the temperature it reports is an average of hotter and colder regions of the moon.

“These temps are lower limit temperatures for what’s in the crack,” Lunine said. “Given fact that ammonia and water can melt at 176 Kelvin, we’re really in the range that liquid water could exist.”

“I’d love to have a situation where we actually dipped our toes into the water, although I’m not sure I’d want to do it barefoot,” Lunine said. “But we’re not going to be able to do that. Just the fact that we can sample the water — smell it if you will — by studying the gas in the plumes, is pretty great.”


If ammonia is in the water on Enceladus, could life live with ammonia in the water?


Well, earth biochemistries would certainly not thrive in a water/NH3/salt brine at -170C, although some extreme earth single-cell lifeforms may be able to survive this environment in a non-reproducing spore form for some time. But I could imagine that this environment could be amenable to other alien biochemistries which are not too far-fetched from a chemistry point of view.

In the case of Enceladus, we do not know how long a subsurface liquid water reservoir has existed (assuming it has, as this is still a subject on controversy, some researchers think the outgassing comes from a subsurface clathrate deposit). If the putative liquid water reservoir is short lived, then there may not have been enough time for a lifeform to have evolved. In addition, at these cold temperatures, the energetics are very weak, and many chemical reactions would proceed very slowly compared to what we are used to. This means that the development of life, and evolution, would probably proceed much more slowly than on the warm Earth. Of course I am assuming that the required pre-biotic ingredients are present (which we don't know!).


hi all,

these are great news. As far as livability is concerned, bacteria have been found to survive (and metabolize) in sewage and alcaline lakes at pH as high as 11. Solutions of 15% ammonia would be close to pH11. So this is not a lost cause.
Temperature is another factor though.
Not sure thay have tested that on Earth

Best regards.
An ammonia-water liquid containing 15wt% NH3 has a pH of ~11.3. The addition of large quantities of salts resulting from the influx of chondritic material (see Engel et al. 1994) probably has a negligible effect on this value. As the ocean evolves in composition over time towards the binary eutectic, the pH would have risen only marginally to ~11.4. At the base of the ocean the effect of increasing pressure on the dissociation constant of water means that the pH will be reduced to ~10.5 (Krauskopf and Bird 1995).
Terrestrial alkaliphilic organisms live most comfortably in the pH range 9-11 and there are examples of bacteria that can grow actively at pH=12 (e.g. Thimann 1963). Alkaliphilic organisms and there adaptations are reviewed by Horikoshi (1996) and Jones et al. (1999). Clearly, even the upper limit of the ocean pH (11.4) represents no significant barrier to life and we shall move on to consider viscosity."


I would like for us to find life on another planet or moon, but I think we all know by the data from Nasa is that no planet or moon in this solar system has a suitable planet for us or any intellegent life. We need to move on to other solar systems as fast as we can and quit wasting time and money on dead end projects. I am all for learning all about every planet and moon in our solar system, but lets face it, we do not have the money. I say the govenment needs to use what money we can get from them and build bigger, better satellites, to find a really suitable world soon, before something happens to this one and we really have to leave it.


Way too hard right now!

It would take us thousands of years just to get a small probe there. There is no point sending one yet, because a probe we send a century from now would arrive before one we send today. That is because in a century we will be able to send much faster probes.

However our ability to learn about planets using telescopes in increasing at a great rate. We may well have the ability to detect evidence of life on earthlike planets in decades or less.

Have a look at this link which talks about what we have already discovered about planets outside our solar system.


Very interesting.

Thge existence of Ammonia in itself does not prove the existence of liquids H20 under the Tiger tripes, but whether or not it is sufficient to lower the melting point to the 163 K mentioned would depend on the concentration of the ammonia, prior to it being erupted in the plumes.

Myself I am not sure as to liquid under Enceladus's surface, warmer ices could explain it & the terrain to me looks like the area is freezing over.

I still think the south polar region of Enceladus marks the site of a giant impact in the not so distant geological past & we are seeing the fossil heat from that event being released.

What would be an interesting thing to do would be to see if Cassini can find ammonia deposits on Tethys & Mimas, Enceladus's neighbours (Europa & Amalthea have sulphur coatings from volcanic Io in the Jupiter system, so I am using the same logic here) & such deposits could give a clue as to how long this has been happening, or it is episodic, continuous, etc.

Just a thought.

Andrew Brown.


3488":3exfmjpd said:
I still think the south polar region of Enceladus marks the site of a giant impact in the not so distant geological past & we are seeing the fossil heat from that event being released.......

Andrew Brown.
I agree 100%. It's the least complex answer to the mystery, my dear Watson. ;)
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