Ganymede, biggest moon in the solar system, has a saltwater ocean

[n2doc]

NASA says new observations from the Hubble Space Telescope confirm the existence of a salty subsurface ocean on Ganymede, the largest moon in the solar system, which orbits our largest neighbor planet, Jupiter.

The ocean is estimated to be about 60 miles thick -- 10 times deeper than the Mariana Trench, the deepest part of the Pacific -- but is buried under a layer of mostly icy crust 95 miles thick. Ganymede joins other neighborhood moons like Enceladus, the asteroid belt dwarf planet Ceres, and Saturn's Europa and Titan that host strange icy or liquid layers, making them prime targets in the search for life beyond Earth.

Scientists have hypothesized for decades that Ganymede might harbor an icy or even liquid ocean beneath its frigid surface. The key to confirming the presence of a saltwater ocean came from observing Ganymede's aurorae, which would look bright red to a human able to stand on the surface of the moon and gaze up through its thin oxygen atmosphere. But don't get too excited, it's much too thin to support life as we know it.


Auroral phenomena -- think the bright northern lights of the aurora borealis or the aurora australis down south -- are not fully understood, but are linked to magnetic fields interacting with the solar wind. Ganymede is the only moon in the solar system that generates its own magnetic field thanks to its liquid iron core, but it also lies within the magnetic field of massive Jupiter. As Jupiter's magnetic field changes, it affects the aurorae on Ganymede, causing them to "rock back and forth" according to Joachim Saur, a professor for geophysics at the University of Cologne, who presented the news on a NASA teleconference Thursday.

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http://www.cnet.com/news/the-biggest-moon-in-the-solar-system-also-has-a-confirmed-ocean-says-nasa/

[tridim]

1. It's an inside-out world.

I would be shocked if there wasn't life there.

[padfun]

2. If water is necessary for our definition of life,

Then the cosmos has to be full of life. That is, if most solar systems have ort clouds around them.

[MillennialDem]

6. That's actually irrelevant, heard it was pretty much proven recently that most of the

water was delivered to Earth during its formation and then released by volcanic eruptions. Of course comets did deliver some of the water.

The reality is hydrogen is the most abundant element in the universe, helium is the second, and oxygen is the third. Since helium doesn't react with anything, water is the most abundant or one of the most abundant compounds in the universe. H2O

[NickB79]

3. An ice mantle seperates the rocky mantle from the ocean? Might be a problem for life?

Life on a world such as this would need hydrothermal vents to supply heat and nutrients to support a food chain.

With such a deep ice mantle between the liquid water layer and the rocky mantle where hydrothermal vents would form, could sufficient volumes of nutrients move upwards to support an ecosystem?

[Confessor412]

4. Life, Life Everywhere

Soo.... first Europa, and now Ganymede?

[goldent]

5. Based on our experience on Mars

I'm not jumping to any conclusions.

[MillennialDem]

7. How much liquid water have we found on Mars? Virtually none, I think we found some mud once but

haven't actually dug into it.

Given all the dust storms it would be hard to find proof of long dead microbes even in a dried out lake / ocean bed. We need to dig into the subsurface and see if there is still liquid water underground and check there.

[goldent]

9. I think Nasa have been diligently looking for signs of past life,

as I do believe they are quite sure there was flowing water in the past. I guess my question would be "if earth only ever had microbe live, and then the earth dried up and all life died, would you have found past life with the rovers?" My impression is that the answer is yet, but I',m not sure.

I think we simply don't know what conditions are necessary for the creation of life, and if all of the those conditions are present, what are the chances of it occurring. I thought that the idea was if the conditions were present for a hundred million years or so, life will develop. There is then the question of what would it take to evolve to higher life forms.

[MillennialDem]

10. Like I said I can't imagine that's easy to find with the amount of dust storms mars has been having

for tens of millions of years.

[MillennialDem]

8. Europa then Enceladus then Ganymede. Enceladus might be even more friendly to life than

either of the other two (less pressure in a smaller ocean).