Giant Impacts May Not Create, But Destroy, Subsurface Oceans on Moons

Scientists from the Weizmann Institute and NASA have utilized computer modeling to investigate the impact of large collisions on the formation and persistence of subsurface oceans on moons and dwarf planets within our solar system. These subsurface oceans, located beneath icy crusts, are of significant interest to astronomers due to their potential to harbor conditions suitable for life. Such oceans are considered possible on moons of Jupiter (Europa, Ganymede, Callisto), Saturn (Enceladus, Titan, Dione, Mimas), Neptune (Triton), and the dwarf planets Pluto and Ceres.

The research specifically explored whether smaller moons of Saturn and Uranus, including Titania, Oberon, Ariel, Umbriel, and Miranda, could develop liquid oceans following massive cosmic impacts that release substantial energy capable of melting ice. The findings indicate that these colossal impacts do not foster the creation of new ocean worlds. Instead, they tend to diminish the size and lifespan of existing oceans.

During a catastrophic collision, a mixture of ice and rock is formed. As the ice melts, the denser rock rapidly sinks to the core, hindering further ocean development and ultimately leading to complete freezing. This study, published in Nature Astronomy, highlights the vulnerability of subsurface water reservoirs on smaller celestial bodies in the solar system.

"Imagine a small frozen moon, nothing interesting happening," explained co-author Dr. Alyssa Rhoden. "If a massive impact happens, will it give enough energy to form an ocean? Our models showed that it's incredibly difficult. In most cases, the destruction of a small moon leads to the loss of the ocean or prevents it from forming."