Chuck Bednar for redOrbit.com – Your Universe Online
Ever wonder what the formation of an asteroid crater on Earth would look like if viewed in slow-motion? Researchers from the University of Minnesota have found a unique way to model such an event by recording the impact of raindrops on sandy surfaces.
Runchen Zhao, Qianyun Zhang, Hendro Tjugito and Xiang Cheng from the school’s Department of Chemical Engineering and Materials Science studied the impact created by precipitation using high-speed photography with high-precision laser profilometry. They investigated the dynamics of liquid-drop impacts on granular surfaces, as well as the resulting impact craters.
As Popular Science explains, as water droplets hit tiny glass beads, they spread out horizontally and form a small crater. The water then retracts, carrying with it a layer of granular particles, and bounces back up. At higher velocities, the droplets spread out across the surface even more. As a result, it picks up more sand, increasing the water’s weight and reducing the height of the jump.
“Increasing the energy of the impact causes the water to take on finger-like projections,” the website continued. “These pick up so many particles that the retraction gets interrupted; it no longer forms a perfect sphere. At very high impact speeds, the finger-like projections spread even further and pick up enough grit that they stop bouncing back.”
The findings, which are detailed in a paper published earlier this month in the Proceedings of the National Academy of Sciences, will help scientists better understand soil erosion and enhance the effectiveness of drip irrigation. However, it will also serve as a small-scale model of the energy distribution caused during an asteroid impact and the crater formation that follows.
For instance, Popular Science noted that the study authors found that the ratio of a crater’s depth to its diameter is approximately 0:20, which is a near-perfect match to that observed in simple craters found on Mercury, Mars and the moon.
“While the asteroid data is helping the Minnesota researchers model the dynamics of a water droplet, the authors suggest that the water droplet data may also be helpful in modeling asteroid impacts,” the website said. “That’s because when an asteroid crashes into a big object, such as a planet, the extreme heat and pressure liquefies or vaporizes the asteroid.”
While the phenomena are similar, the authors caution not to draw too close of a link between them. An asteroid’s impact energy is 18 orders of magnitude bigger than a water droplet’s, and the discrepancy indicates that there are likely different physical processes involved, they noted.
Even so, they wrote that there was “a quantitative similarity between liquid-drop impacts and asteroid strikes in terms of both the energy scaling and the aspect ratio of their impact craters,” and that the similarity “inspires us to apply the idea developed in planetary sciences to liquid-drop impact cratering, which leads to a model that quantitatively describes various features of liquid-drop imprints.”
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