Enceladus in Thermal Disequilibrium: Tidal Dissipation at the Present Eccentricity Against the Measured Heat Output

Enceladus radiates more heat than steady tidal dissipation at its present eccentricity comfortably supplies, and this study puts the shortfall in numbers. The standard dissipation formula with a dissipation factor k2 over Q of 0.01 gives 14.91 gigawatts, which barely matches the measured south polar output alone of 15.8 gigawatts and leaves nothing for conductive losses through the rest of the shell, whose global total has been estimated at 25 to 40 gigawatts. At a factor of 0.002 the supply is only 2.981 gigawatts. Only the generous factor of 0.05, yielding 74.53 gigawatts, covers the global estimates in steady state. Either the dissipation factor is at the high end, or Enceladus is spending heat stored during an earlier epoch, or dissipation in a porous rocky core contributes beyond the ice-shell term. Computed from stated assumptions, not measured.