Oceans Potentially More Common In Solar System 182
nairolF writes "The AIP Physics News Update has a brief note on how water oceans might be more common in the solar system than previously thought, rendering useless the old notion of a narrow "habitable zone" in solar systems, outside of which life cannot exist."
Another related article... (Score:3, Informative)
Shameless journal plug? Not really, just an article the was rejected...
Dr. Stevenson previous paper (Score:5, Informative)
Other forms of life? (Score:4, Informative)
It strikes me as rather narcissistic to believe that the definition of life is somehow rooted to the way things worked out on this planet...
Can anyone think of any other substances that behave as dynamically as water in different temperature ranges?
Seriously.... (Score:3, Informative)
The article:
""Oceans might be common and diverse in our solar system and in other solar systems, according to David Stevenson of Caltech, who regards the old notion of a narrow "habitable zone" (Venus too hot, Mars too cold, Earth just right) for liquid water oceans as erroneous.
Stevenson spoke earlier this week in San Francisco at a meeting of the American Geophysical Union at a session intended to bring together two scientific communities that scrutinize very different realms--the planets and the seafloor on Earth.
The connection? Observations from the bottom of the ocean show that microbes thrive both in near-freezing seawater and in near-boiling effusions from thermal vents. These conditions might turn up in many other planetary environments.
For example, the Galileo spacecraft has provided evidence for watery oceans on three of Jupiter's moons-Callisto, Ganymede, and Europa. Subsurface oceans could be kept liquid by warmth from tidal forces (Jove wringing its satellites) or from radioactivity. Torrance Johnson of JPL, also speaking that the meeting, said that Europa's ocean might be 75-150 km thick and could thus harbor twice the water in Earth's oceans.
Stevenson added that observations also hint at oceans on Titan, Triton, and Pluto. In the case of Titan (soon to get the Galileo treatment when the Cassini spacecraft reaches Saturn in 2004) an ocean would be a mixture of water and ammonia (acting as antifreeze). Under some circumstances water might even be found inside Uranus and Neptune.""
Europa does have very likely evidence of a liquid ocean, but the article then uses that to 'assume' of living creatures there (bac). How can there be? Complex nucleotides and a slurry of other complex chemicals are required for 'life' to occur. Another problem is energy entering/leaving the system. The Earth is quite close to the sun, but europa can rely on nearly 0 energy from the sun (at least as useful radiation). Tidal energy is energy none the less, but it's too limited, even coming from Jupiter.
Energy, yes but useful, no.
Josh Crawley
Oceans, oceans everywhere... (Score:5, Informative)
Also, on Earth, there is a plethora of water below the surface, although you would not want to drink it. It's usually saturated in salts like calcium or sodium chloride, carbonates, and sulfates. However, even 10 km below the surface of the Earth, in hot conditions and high pressures, 0bacteria thrive in these conditions (as they do in the Hydrocarbon deposits as well).
Given that Mars has plenty of surface evidence of (geologically) recent free flowing water, the scientific community would be remiss to assume that subsurface water does not exist. It likely has a lot of brine belows it's surface, perhaps rich in Iron salts.
Also, there are moons of Jupiter, like Europa (which is basically 10 km of ocean from what we can see on the surface) and Ganymede (with a lot of hydrocarbons) where conditions that bacteria and simple one celled life require exist. Given that we have already learned that bacteria in hostile environments on Earth (Antarctica, for example, in very dry and cold conditions) can hibernate for millions of years, it's conceivable that rocks knocked loose from Earth from the occasional large meteor (i.e. asteroid or comet) could transport bacteria to Mars and elsewhere. I think that if life did not evole there, it was transported from Earth by this process (or perhaps even the other way). Some people have speculated that bacterial or similar life found on Mars or elsewhere within this solar system is completely different from that found on Earth -- I would postulate that it is probably no more 'alien' that what we might find in the ocean near black smokers, that big underice lake in Antarctica (can't remember the name), or a barren, cold, high altitude mountain.
---this is not your kill9 sig
Re:Other forms of life? (Score:3, Informative)
Yeah, science fiction has postulated silicon-based life (the kind Kirk almost killed in ST:TOS), or chlorine breathers (like the Kloros in that Asimov story, C-Chute), but I haven't heard that anyone has postulated any plausible biochemical processes (akin to ATP) that could support such life. Anyone got any pointers?
Argh (Score:5, Informative)
Ok, lets get some things straight. There's evidence that liquid water can exist in places outside our old 'habitable zone'. We know that organisms can thrive in boiling and subzeo (but still liquid) water, as well as surviving frozen inside ice (as happens annually in the ice shelves of antarctica).
So, this means that its *possible* for life as we know it to exist in these extraterrestrial oceans. No one is saying its there, just that its worth a look. Likewise, no one has proven that life can't exist without water. However, the only kind of life we *know* exists, does require water, and is carbon-based. I hope someday that we find that life exceeds this "narrow" category, but since we'd first just like to find any life at all, where do you think we're going to look? For the moment, time, energy, and resources are most likely to give results if we apply them according to our best information about life, however meager.
Rant over. Now get the hell off my lawn you kids!
Re:Seriously.... (Score:3, Informative)
Bacteria are tough; they can spore up and be very hard to kill. (That's why anthrax is such a bitch to deal with.) Earth bacteria survived for several years unprotected on the moon [nasa.gov].
doubtful (Score:2, Informative)
There really aren't a lot of other choices. It is unimaginable really to have life (at least any kind of life we could interact with) in solid or gaseous form, so you need a solvent. Methane, carbon dioxide, helium, and hydrogen are abundant but nowhere near as versatile as water. Liquid ammonia or some mix of solvents might work, but they don't look promising.
So, people have thought about this but not really come up with any plausible alternatives so far. Water and carbon seems to be the only reasonable cohice. But if someone can make a plausible argument, I think the scientific community is receptive.
pedants corners. (Score:2, Informative)