Lab tests suggest water brines could also exist on large asteroids
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In attempting to explain the existence of flow features that have been found on the interior walls of craters on the asteroids Ceres and Vesta — as shown in the image above — scientists recently performed a laboratory experiment which determined that a mixture of water and salt could produce those gullies.
The team modified a test chamber at the Jet Propulsion Laboratory to rapidly decrease pressure over a liquid sample to simulate the dramatic drop in pressure as the temporary atmosphere created after an impact on an airless body like Vesta dissipates. According to Poston, the pressure drop was so fast that test liquids immediately and dramatically expanded, ejecting material from the sample containers.
“Through our simulated impacts, we found that the pure water froze too quickly in a vacuum to effect meaningful change, but salt and water mixtures, or brines, stayed liquid and flowing for a minimum of one hour,” said Poston. “This is sufficient for the brine to destabilize slopes on crater walls on rocky bodies, cause erosion and landslides, and potentially form other unique geological features found on icy moons.”
The press release makes it sound as if this result makes the existence of subsurface water ice more likely on such asteroids as Ceres and Vesta, but previous research from the Dawn asteroid probe made that fact very clear, especially for Ceres, years ago. All this does is provide some evidence of what might be one process by which these erosion gullies form.
Hat tip to reader Milt.
