Neptune’s moons bear water-rich clues from a catastrophic past

JWST observations detect magnesium-rich phyllosilicates on Neptune’s inner moons Larissa and Galatea, implying subsurface ice and past interior heating before their destruction, while Proteus lacks these minerals; a proposed scenario suggests Neptune’s original moon system was destroyed by Triton’s capture, scattering materials into a debris disk that formed rings and current moons, with an unidentified hydrated mineral common to all three moons and an alternative hypothesis that it came from a tidally disrupted Kuiper Belt object.