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Cassini Finds Evidence For Ocean Inside Titan
Riding with Robots writes "NASA reports that by using data from the Cassini probe's radar, scientists established the locations of 50 unique landmarks on the surface of Saturn's planet-size moon Titan. They then searched for these same lakes, canyons and mountains in the data after subsequent Titan flybys. They found that the features had shifted from their expected positions by up to 30 kilometers. NASA says a systematic displacement of surface features would be difficult to explain unless the moon's icy crust was decoupled from its core by an internal ocean, making it easier for the crust to move. If confirmed, this discovery would add to the growing list of moons in the solar system that are icy on the outside and warm and liquid inside, providing potential habitats. We've previously discussed Titan's hydrocarbon lakes and potential cryovolcano."
Life ON gas giants seems like a big NO with what we currently know about the conditions required for life to emerge. But life around gas giants, on their moons seems plausible.
What I'd like to know (read: what I'd like some slashdotter with the required know-how explain to me) is why are these moons hot on the inside, possibly hot enough for water ice to turn into liquid water. It's so incredibly far away from the sun. Is this caused by their size and subsequent internal dynamics?
Also, aren't these moons constantly bombarded with radiation from their host planet's powerful magnetic field? Must be rough for aliens.
Don't forget that the melting point of water *decreases* as pressure increases. The liquid core may well be damned cold!
While it is very likely that the interiors of a couple moons in the solar system have subsurface liquid oceans, that does not indicate high enough temperature at depth to consider the interior warm or hot or capable of supporting life. Over geologic time these subsurface liquids (which are thought to be predominantly H2O) have more likely formed through interaction with surrounding rock/metal. As H2O reacts with its surroundings and incorporates various impurities (salts, ammonia, organic molecules) into its structure the melting point is decreased to the point that a liquid or fluid condition is possible at significantly lower temperatures. Although in the case of Ganymede (Jupiter's fourth moon), which posses an internally generated magnetic field, a dynamo action similar to Earth's core may exist providing heat. Whether this is the case on Titan is yet to be determined. The massive amounts of organic components there make it harder to determine if there is an internal heat source or if the mixture of organic compounds are naturally stable at those conditions creating the lakes and cryovolcanoes previously mentioned.
Too bad Arthur C. Clarke passed away on Tuesday (Wed. in Sri Lanka), he would have been very pleased to have his suspicions confirmed like this. Then again, maybe he's hanging with Dave Bowman and HAL. In that case his response might be whatever a stylish English gentleman says instead of "Duh!".
Rest in peace, Sir Arthur, and thanks for giving us "all these worlds."
-- a sad fan who's enjoyed your books for over 20 yearsQuantum mechanics: the dreams that stuff is made of.
There are so many hydrocarbons observed in the universe outside Earth that we haven't even identified all we've discovered. The environment of Earth in its early history was chemically much like that of the present-day gas giants: reducing. This is a critical point because it allows hydrocarbon synthesis and re-synthesis. Self-replicating molecules can, in theory, be very simple compared to what you probably referred to hand-wavingly as "life" just now. Sagan (along with others, IIRC) proposed "floaters" and "hunters" as entirely viable, but hypothetical forms of life viable on a gas giant such as Jupiter. These represent complex multicellular life and not Archaea-like single-celled life, which would be more likely, let alone simpler self-replicating biopolymers like DNA or RNA, or perhaps something more exotic.
Earth's present environment (for the last 2.5-3 billion years) has been oxidizing rather rather than reducing, due (per current theory) to the average thermal speed of light molecules exceeding that of local gravity (we know this is the case, but of course we have to take an educated guess that it's actually the cause and not simply a true but irrelevant consequence of physical laws).
The problem is not so much that even the ancestor of Life As We Know It is impossible on gas giants, but rather our inability to determine the likelihood of life arising in an environment given an environment capable of sustaining life. In the language of the Drake Equation, we know Ne poorly is irrelevant because we know it's at least as big as Fl and we think that Fl is probably much less than 1 (i.e. life doesn't always arise even when conditions are suitable to sustain it).
It's not so impossible that there is life on gas giants, even if it is improbable in the minds of some very different life forms from a very different environment.