For the Jupiter's gravitational field, the gravitational potential energy at the surface of Europa is Vgr=GMJm/REu and defines the maximal value Δ Emax of the metabolic energy quantum for a flux loop defining dark gravitational HB oriented radially outwards along A line connecting Europa and Jupiter. The mean distance dEu from Jupiter is dEu= 105.3× RE to be compared with the radius RJ=10.97 RE of Jupiter. The mass of Jupiter is MJ= 317.8ME. This gives Δ Emax,Eu/Δ Emax,E=Vgr,J/Vgr,E= (MJ/ME) × (RE/dEu)≈ 3.0.
For a single gravitationally dark proton, the maximal metabolic energy gain would be .99 eV, which is twice the metabolic energy quantum. Standard metabolic energy quantum .5 eV corresponds to a radially oriented loop with height h=dEu. If a proton triplet defines the metabolic energy quantum, one would have h=(1/5)REu.
Solar radiation should provide the metabolic energy. The average distance dJ of Jupiter from Sun varies between 5.0AU and 5.4AU so that the gravitational metabolic energy quantum has upper bound Δ Egr,Sun,J \leq Δ Egr,Sun,E/5≈ .5 eV, which corresponds to metabolic energy quantum. Photosphere produces IR radiation with energies in the range .4-.6 eV. Therefore Europa seems to satisfy the conditions from quantum gravitational metabolism.
See the article Quantum gravitation and quantum biology in TGD Universe or the chapter with the same title.
For a summary of earlier postings see Latest progress in TGD.