资源环境科技发展态势分析平台

Jupiter’s moon Europa is thought to have an ocean beneath its ice shell and the habitability of the internal ocean depends on the availability of redox gradients. Downward transport of radiolytic materials produced at the surface through the ice shell sets the flux of oxidants into the ocean. Here, we propose that oxidants are transported through the ice shell by the drainage of near-surface brines formed concurrently with chaotic terrains. We estimate that Europa’s porous regolith contains 3.7 × 10¹⁴ to 5.6 × 10¹⁸ moles (1.2 × 10¹³ − 1.8 × 10¹⁷ kg) of trapped O₂. Simulations of coupled melt-migration and eutectic phase behavior show that brines drain before they refreeze, delivering ∼85% of the surface oxidants to the ocean on timescales of 2 × 10⁴ years. From the distribution of chaotic terrains and from Europa’s surface age we estimate that brine drainage could deliver O₂  to the ocean at rates of 2.0 × 10⁶ to 1.3 × 10¹⁰ mol/yr.