Geronimo Luis Villanueva

Ocean-sourced CO2 Boosts Radiolytic Oxidants at Europa’s Chaos

Abstract James Webb Space Telescope (JWST) observations of Europa’s leading hemisphere reveal enhanced CO 2 abundances over equatorial chaos terrains where the subsurface ocean is thought to have breached the ice shell. Hydrogen peroxide, synthesized radiolytically by Jovian magn...

JWST Reveals Refractory-rich Water Ice in Interstellar Comet 3I/ATLAS: Evidence for a Continuum of Grain Properties across Protoplanetary Disks

Abstract We present JWST/NIRSpec PRISM observations of the interstellar comet 3I/ATLAS obtained on 2025 August 6 (Epoch 1), 2025 December 22 (Epoch 2), and 2026 April 1 (Epoch 3), spanning 8 months around perihelion at heliocentric distances of 3.3, 2.4, and 5.7 au, respectively....