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The liquid water requirement tells us a life-bearing planet can't be too hot, but finding life in the deepest parts of the ocean suggests that the water may not
by mc808 12y ago
The liquid water requirement tells us a life-bearing planet can't be too hot, but finding life in the deepest parts of the ocean suggests that the water may not need to be on the surface. The nutrition raining down from the surface ultimately links back to photosynthesis, though, so it's not entirely convincing evidence.
The "habitable zone" concept is still useful when it comes to actually searching for signs of life. I'm guessing a planet with organic life on the surface would have stronger signatures than one with a thriving ocean under 500 km of solid rock and ice.
- SideburnsOfDoom 12y ago> The nutrition raining down from the surface ultimately links back to photosynthesis This is a key point. The trench lives on the spillover from the surface. If there was no habitable surface full of life, there would be no life in the trench. Have a read of http://en.wikipedia.org/wiki/Whale_fall http://en.wikipedia.org/wiki/Whale_fall - the deep ocean floor may host ecosystems, but this does not mean that planets where the best conditions are like the deep ocean floor are "habitable". Similarly, the presence of mosses and lichens in Antarctic dry valleys is interesting, but does not prove beyond doubt that such organisms could evolve if the best conditions were like that.