Signs of Water Found On Saturnian Moon Enceladus 79
Matt_dk writes "Scientists working on the Cassini space mission have found negatively charged water ions in the ice plume of Enceladus. Their findings, based on analysis from data taken in plume fly-throughs in 2008 and reported in the journal Icarus, provide evidence for the presence of liquid water, which suggests the ingredients for life inside the icy moon. The Cassini plasma spectrometer, used to gather this data, also found other species of negatively charged ions including hydrocarbons."
Re:The pendulum swinging (Score:5, Informative)
There are creatures on earth that do not get their energy from the sun - they live near hydrothermal vents [wikipedia.org] deep in the oceans. That's one possibility that we have seen ourselves; in fact it was this discovery in part that spurred on the search for life on other planets that would normally have been written off as far as supporting life was concerned.
Re:Why would liquid water... (Score:5, Informative)
Have scientists been able to throw together basic ingredients of living things and have the resulting pile resemble anything even close to life? Even in perfectly favorable lab settings?
yep [wikipedia.org]
(Depending on how you define "life", of course)
Re:The pendulum swinging (Score:4, Informative)
Isn't distance from the sun pretty empirical, though?
Not exactly, and not really.
Any source of heat will do, the sun is just a convenient free source of it for those planets near enough, and while not technically unlimited, is close enough for our current needs and not even an issue for any society under a KT-I level (like us)
Earth's 'sweet spot' is occupied by, well, Earth, and little else. This moon of Saturn may have water, but where is it getting its replacement for solar power?
The main source of heat is the same as Earths secondary source of heat.
Left over energy from the planets (or moons) formation in the early solar system. Typically the symptoms of this are a molten semi-liquid core, and centrifugal forces imparted to it during it's creation.
Also Europa has Saturn and it's magnetic field and gravity well to generate energy.
As the moons orbits are not circular but instead elongated, this means in a single trip around it's host body, half the time it is closer to the planet than the other half (and in seasonal quarters like Earth has) which gravitationally pulls on the moons surface stronger during the closer orbit times.
This process generates a bunch of geothermal activity, motion, and heat energy from friction.
http://en.wikipedia.org/wiki/Tidal_flexing [wikipedia.org]
The top layer of ice is very thick, and only the first couple meters are needed before the suns radiation are blocked enough to not be damaging to anything under that level.
Moving water (and thus food) due to tidal flexing between the liquid inner layer (be it water or whatever it happens to be) and the frozen solid crust.
A hot and mobile semi-liquid metallic core to provide heat to the lower levels that don't get much or any energy from the sun.
If it wasn't for the fact the rest of Earths ecology wasn't there, there are a number of life forms on Earth that we could drop off under the ice right now and they would have an extreamly high chance of survival (again admitting, with a support and food supply)
If life was to or has started from the basics there, the foundation of support for an ecology would be in place (at least for life that evolved there), and there is plenty of sources of energy compared to current known life forms on earth (not us, but humans are far from the life form majority on this planet)
My guess - it isn't.
While you may be correct, it would only be correct by accident :)
We have many life forms on earth that already thrive in such conditions. So we have solid proof that such a thing is possible, and there is no reason to think otherwise.
But as we know, just because something is possible, doesn't mean it has happened more than once.
Nor are there any actual arguments if there IS life there or not, only guesses.
Within the realm of possible however, it has been proven to be possible already.
Re:The pendulum swinging (Score:5, Informative)
So you're operating under the assumption that these lifeforms evolved independently from a spontaneously-generated source?
No. It is only establishing that it is possible for life to exist in such environments.
I agree it's probable that the examples on earth evolved from life that formed where solar energy was readily available. But that doesn't necessarily mean its the only possible evolutionary path, any more than our history means warm blooded live-birthing animals can only evolve in the presence of giant reptiles who get conveniently wiped out by meteors. It also doesn't mean life can begin and evolve strictly from geological energy sources... We don't really have a good model of abiogenesis, but the things we're pretty sure are at least prerequisites are water, organic compounds like amino acids, and energy.
I'm not ready to say that the source of energy must be the sun.
Re:The pendulum swinging (Score:5, Informative)
There is also a fairly common biological origin hypothesis that the thermo-chemical powered life found near vents was the earliest kind of life on earth and solar powered life evolved from it. This hypothesis fits our current understanding of earths early seas rather well. Though I don't think there is any way to advance it to a theory due to the near absolute lack of fossil records from that period.