NASA scientists have conducted a reanalysis of data from NASA's Voyager spacecraft, combined with new computer modeling, which suggests that four of Uranus' largest moons may harbor extensive oceans beneath their icy crusts. The study, focusing on the moons Ariel, Umbriel, Titania, Oberon, and Miranda, provides valuable insights into the evolution and interior makeup of these enigmatic celestial bodies. The findings not only enhance our understanding of the Uranian system but also have broader implications for the prevalence of oceans in other icy bodies across the solar system.
With a total of at least 27 moons, Uranus is a fascinating ice giant that has captured the curiosity of planetary scientists. The four largest moons, ranging from the 720-mile-wide Ariel to the 980-mile-wide Titania, have been the primary focus of this study due to their potential to retain internal heat. Until now, it was widely believed that only Titania, given its size, could maintain an internal ocean due to radioactive decay-generated heat. However, the latest research challenges this assumption, suggesting that the other moons could also contain oceans dozens of miles deep.
The study draws upon the data obtained during NASA's Voyager 2 flybys of Uranus in the 1980s, as well as ground-based observations. Researchers utilized advanced computer models incorporating information from subsequent missions like Galileo, Cassini, Dawn, and New Horizons, which discovered ocean worlds in our solar system. By applying these findings to the Uranian moons, scientists gained valuable insights into their porous surfaces, suggesting sufficient insulation to retain internal heat necessary for hosting oceans.
The researchers identified potential heat sources in the moons' rocky mantles, where hot liquids are released, contributing to a warm environment for the oceans. This scenario is particularly probable for Titania and Oberon, where the oceans may even reach temperatures suitable for supporting habitability. By investigating the composition of these oceans, scientists aim to understand the materials present on the moons' icy surfaces, potentially originating from geological activity that pushed substances from below to the surface.
The study also reveals the likelihood of abundant chlorides and ammonia in the oceans of Uranus' largest moons. Ammonia has long been recognized as an antifreeze, while the presence of salts in the water would provide an additional source of antifreeze, ensuring the stability of the internal oceans. Surface features on some of the moons, such as Ariel and Miranda, suggest recent geological activity and the possibility of material flowing onto their surfaces, potentially indicating the presence of icy volcanoes.
The research findings have significant implications for future missions to Uranus and beyond. The National Academies' 2023 Planetary Science and Astrobiology Decadal Survey has prioritized the exploration of Uranus, making it crucial to deepen our knowledge of its moons. The study's insights into the composition and potential habitability of these moons will inform the design of scientific instruments and exploration strategies. Spectrometers, capable of detecting compounds based on their reflected light, will need to cover a wavelength range suitable for identifying both ammonia and chlorides. Furthermore, engineers will need to develop instruments capable of probing the deep interiors of these moons to search for liquid and electrical currents, which may indicate the presence of hidden oceans.