7 December 2016 · Published

New Proof Ganymede Was Once Europa

WordPress backup · published post (same notes as a 6 Dec 2016 draft cut from a paper)

“Ganymede’s period of geologic activity should have ended by ~4 Ga (e.g. Reynolds and Cassen, 1979; Schubert et al., 1981; Friedson and Stevenson, 1983; Kirk and Stevenson, 1987).” — Patterson, Head et al., LPSC 2007, a global geologic map of Ganymede.

“Recent ground-based observations of the Galilean moons and analysis of historical data suggest that the satellites evolve out of resonance, implying that Ganymede is receding from Jupiter (Lainey et al., 2009).”

On delayed differentiation: complete differentiation of Ganymede “would occur later in Ganymede’s history… possibly triggered by tidal heating during passage through one of the Laplace-like resonances.” Surface-area expansion from remelting a differentiated satellite is “less than half of the strains measured on the surface.”

Malhotra 1991; Showman and Malhotra 1997: the Galilean satellites may have passed through one or more Laplace-like resonances before the current lock, involving 2:1 pairs Io–Europa and Europa–Ganymede.

The live Ganymede page uses these as analog notes. Identity is still medium.