Fp. Fanale et al., An experimental estimate of Europa's "ocean" composition independent of Galileo orbital remote sensing, J GEO R-PLA, 106(E7), 2001, pp. 14595-14600
We have conducted a series of experiments designed to simulate, in the labo
ratory, the development of any subsurface aqueous phase on Europa. In our t
heoretical-experimental approach we select a single natural sample (a CM me
teorite) that based on cosmochemical considerations, we consider to approxi
mately represent the bulk material that accreted to form Europa. We then su
bject the sample to a hot water leaching procedure designed to simulate low
- to moderate-temperature aqueous alteration. The resulting leach solution
was then subjected to a series of sequential fractional crystallization ste
ps producing a series of ices and residual brines. Then all this brines and
ices are multiply analyzed for Na, Ca, Mg, Sr, Ba, Fe, Mn, K, Cl, and SO,.
Results were found to be remarkably consistent between brines and ices in
the same stages of crystallization and also between stages. We found that a
ny putative aqueous phase below Europa's ice crust is probably a brine with
cations: Na similar to Mg > Ca, K > Fe and anions: SO4 > > Cl. Our results
are in harmony with inferences drawn from one of the two main current inte
rpretations of the orbital spectral data but cannot definitively rule out i
nferences drawn from the alternative interpretation. This is so because the
mineralogy of the top 200 mum may not reflect the chemical composition of
bodies of brine below the solid surface owing to extensive alteration cause
d by magnetospheric bombardment.