NASA’s Dawn mission has provided evidence that giant asteroid Vesta was home to sudden and brief flows of water that carved gullies and deposited fans of sediment. A recent study, funded by NASA, suggests that impacts on Vesta triggered these flows, which were made possible by the presence of sodium chloride – or table salt.
The study used lab equipment to mimic conditions on Vesta and found that pure water froze almost instantly, while briny liquids stayed fluid for at least an hour. This prolonged flow time is crucial in forming surface features like gullies, which were estimated to require up to a half-hour to form.
To recreate Vesta-like conditions, scientists used the Dirty Under-vacuum Simulation Testbed for Icy Environments (DUSTIE) test chamber. They mimicked the environment around fluid that comes to the surface by rapidly reducing air pressure, resulting in pure water freezing instantly and briny liquids flowing longer before freezing.
The researchers also re-created the “lids” of frozen material thought to form on brines, which stabilize the liquid beneath them, allowing it to flow longer before refreezing. This phenomenon is similar to how lava flows farther in lava tubes than when exposed to cool surface temperatures.
The discovery challenges our understanding of liquids on airless worlds and provides insights into processes on Ceres, where a subsurface reservoir of brine was discovered. The study’s findings contribute to a growing body of work using lab experiments to understand liquid behavior on various celestial bodies.
Source: https://www.jpl.nasa.gov/news/lab-work-digs-into-gullies-seen-on-giant-asteroid-vesta-by-nasas-dawn