Impacts explain traces of flows in airless worlds

Oct. 21 () –

Planetary scientists have found an explanation for the presence of mysterious flow features that exist on the surfaces of airless celestial bodies, like Vesta and Ceres.

In a new article published in The Planetary Science Journal describe how conditions following a meteorite impact could produce liquid brines that temporarily flow along the surface for long enough to etch curved gullies and deposit fans of debris on the walls of newly formed craters.

“We wanted to investigate our previously proposed idea that ice beneath the surface of an airless world could be excavated and melted by an impact and then flow along the walls of the impact crater to form distinctive surface features,” he said. in a statement the principal investigator of the project, Dr. Jennifer Scully, from JPL (Jet Propulsion Laboratory).

The team wanted to understand how long the liquid could potentially flow before freezing again, since most liquids lose stability under strong vacuum conditions.

The research details the team’s findings after simulating the pressures experienced by the ice on Vesta, one of the largest asteroids in our solar system, after a meteorite impact and how long it takes for the liquid released from the subsoil to refreeze.

The team modified a test chamber at JPL to rapidly decrease the pressure on 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 co-author Michael J. Poston of SwRI (Southwest Research Institute), the pressure drop was so rapid that the test liquids expanded immediately and drastically, expelling material from the sample containers.

“Through our simulated impacts, we found that pure water froze too quickly in a vacuum to produce a significant change, but salt-water mixtures, or brines, remained liquid and flowing for a minimum of an hour,” Poston said. “This is enough for the brine to destabilize the slopes of the crater walls of rock bodies, cause erosion and landslides, and potentially form other unique geological features found on icy moons.”

These findings could also help explain the origins of certain features observed on distant bodies, such as Europa’s smooth plains and the distinctive “spider” feature in its Manannán crater, or the various fan-shaped ravines and debris deposits on Mars. The study could also help build a stronger case for the existence of groundwater in seemingly inhospitable places in the solar system.

“If the results are consistent in these dry, airless or thin atmosphere bodies, this shows that water existed on these worlds in the recent past, indicating that it could still be ejected by impacts,” Poston said. “There may still be water to be found.”