> HOWEVER: the analyses of Europan impact-gardening rates conducted since this > paper by Chyba and others strongly suggest that the oxidants and organics > created in Europa's upper film of ice by Jovian particle radiation ARE > mostly buried safely before solar UV light can break them back down again. > I am not -- I hope -- wildy optimistic about the possibility of life on > other worlds, but I find these new papers on Europan ocean oxygenation > nothing short of electrifying. If the theory is true, the chances of > Europan life may actually be INCREASED if Europa has little geological > activity on its ocean floor, since this would expose less fresh reduced > rocks and gases to eat up much of the ocean's oxygen.
Interesting! But isn't there a basal layer of MgSO4.7 H20 insulating the ocean from reducing agents on the seafloor in any case? Riff => to be taken with a pinch of epsomite ;-) If the upper limit of 10^12 mols/year is continuously produced and transported, and there are no sinks - animal, vegetable, microbial (call me prejudiced) or mineral (see above) - the ocean will become DO-saturated in a geologically short time. If the ocean is well-mixed this'll take 400 Ma. At ice + water depths of 42 km (if my shums are straight), bubbles will rise to the top of the ocean; below 42 km they will sink.* More to the point, so long as the rate of O2 removal at the base of the ocean is less than the rate of addition (assuming water diapirism is negligible and fresh ice crystallises slowly), O2 will accumulate in a layer at the water-ice interface. The maximum rate, with a 20 km thick shell, would be 2.8 microns per year. Leave that kind of process running for a few million years and you've partially decoupled the ice lid from the ocean, which should cause some iffy stress patterns. So will the first smoker on Europa please light up outside? Ed Kite * If the ocean is extremely well-stratified and convection rare - which is unlikely - K40-generated oxygen will eventually create a "bubble raft" at this depth. == You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] Project information and list (un)subscribe info: http://klx.com/europa/
