JWST Detects Water-Altered Clay on 2 Neptune Moons and Rings, Pointing to Lost Satellites
Updated
Updated · spacedaily.com · Aug 17
JWST Detects Water-Altered Clay on 2 Neptune Moons and Rings, Pointing to Lost Satellites
1 articles · Updated · spacedaily.com · Aug 17
Summary
Larissa, Galatea and Neptune’s rings show a 2.72-micrometre spectral feature that JWST linked to magnesium-rich phyllosilicate clays formed by long exposure to liquid water; Proteus showed hydrated material but little or no sharp clay signature.
1.7-to-4.5-micrometre NIRSpec data were pulled from four faint targets beside Neptune’s glare, revealing deep hydroxyl absorption but no clear water-ice bands, indicating hydrated rock rather than exposed surface ice.
About 200-kilometre Larissa and Galatea are too small and cold—near 50 kelvin—to generate millions of years of internal liquid water, so the clay likely predates the present moons.
The leading explanation is that larger primordial satellites were altered internally, then shattered after Triton’s capture destabilized Neptune’s original moon system; some debris later reassembled into the inner moons and rings.
The finding is the first comparable phyllosilicate detection beyond Jupiter and strengthens the case that Neptune once had a larger native satellite system, though a later tidally shredded icy body remains an alternative.