
Will they find?
"Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn."
Seagoing British boffins are about to plunge deeply into hot Caribbean bottom vents using a long, cigar-shaped, battery powered device. They expect the probings to offer valuable insights into the behaviour of alien life. The Autosub 6000 robot submarine. Credit: NOC The aliens soon gave up their secrets after a good probing …
I think that the relation between 'closeness to the center of the earth' and temperature is rather lose, if it exists at all. At some point I regularly measured the temperature in 8-10kfoot deep holes, and it /never/ got much above 120C. So I imagine that it has more to do with the tectonic plate structure of the area (probably pretty thin were any volcanic activity is located, much thicker where I happened to work) than the slight (on a planetary scale) difference in distance from the center of the earth.
Hi there - here are a few answers from one of those "seagoing boffins" on the ship (great article btw, Lewis - thumbs up from all aboard!).
The animals down there, and many of the microbes, do need oxygen (which has ultimately come from photosynthesis). But their energy source at vents is chemical energy, rather than sunlight. So in terms of *energy*, it's fair to say that they're independent of the sunlit world above (but not in terms of their whole ecology - e.g. see http://deepseanews.com/2009/05/sex-at-vents-lights-on-or-off/).
Sulphide and methane provide the chemical energy sources that microbes at deep-sea vents use to turn inorganic carbon into sugars (just like photosynthesis, but powered by chemical energy rather than sunlight). Basically the sulphide or methane provides a source of free electrons that drives a chain of reactions, but oxygen is usually used to mop up those electrons at the end.
There are *some* microbes down there that are anaerobic, and can pull off that trick without oxygen (some actually use the element tellurium as the "terminal electron acceptor" - the only biological use of tellurium known so far, I think). Those anaerobic microbes are often the ones that are also spectacularly thermotolerant (current record is >120 deg C). But the animals, and perhaps *most* of the microbes, need oxygen.
Although the hot cocktail gushing out of the vents is anoxic, there's plenty of oxygen down there in the surrounding deep-sea water, thanks to the global ocean circulation (deep water forms at the poles, and carries oxygen down from the surface into the depths as it sinks and flows out across the depths; it gets gradually used up, but in most areas the deep water is still oxic).
As for the vents getting hotter with depth, it's not actually because they're closer to the mantle - it is the greater pressure of water above them. If we're lucky, we might see vents in the Cayman Trough topping 500 deg C - which may result in different chemistry compared with vents known so far, and perhaps different life as well...
Anyway, we'll be chatting about this kind of stuff in the daily log on our expedition webpages (www.thesearethevoyages.net) as the trip progresses, for any who are interested.
also arose under similar conditions - which might indeed make it likely that roughly similar forms of life could exist on other planets and/or moons in our solar system, or if it developed from life forms which arose under conditions obtaining on the surface of our planet way back when, which would render it rather less likely that such forms exist elsewhere in the neighbourhood. Can't wait to see what that particular probe into that particular hotspot finds !...
Henri