Researchers used information from underground nuclear testing and exploding volcanos to come a step closer to understanding unusual impact craters on Mars.
The craters exhibit a "thin layered outer deposit" which extends far beyond the range of ejecta a normal impact should be able to reach, a Northern Arizona University press release reported.
Nadine Barlow, professor of physics and astronomy at Northern Arizona University, named the mysterious craters Low-Aspect-Ratio Layered Ejecta Craters (LARLE), and believes she may have an answer as to how the impact's ejections were so far-reaching.
Barlow first noticed the craters when looking over high-resolution images to updater her notorious crater catalogue.
"I had to ask, 'What is going on here?' " Barlow said.
Barlow and her colleagues studied "explosion literature" in hopes of finding an answer, and came across something called a "base surge."
The phenomenon occurs after a large explosion, when fine-grained materials form a dust cloud that travels a considerable distance across the surface of the planet, picking up more materials in its path. This could have been what caused the crater's outer deposit.
The team adjusted the Earthly data on explosions to fit Martian conditions.
"We adjusted the equations for terrestrial volcanic surge deposits by changing gravity and the atmospheric density (which affects the rate at which particles will fall out of the atmosphere) to the Martian conditions. The equations also require estimates of the initial volume of material--we used the volumes of the individual crater cavities to provide those values," Barlow said in an e-mail to Headlines and Global News.
This adjustment allowed the researchers to explain the "thin, sinuous, almost flame-like deposits," the press release reported.
The craters are normally found at high altitudes, which would most likely be characterized by fine-grained sediment deposits necessary for a base surge.
"We're looking in more detail at these deposits to find out what their characteristics are," Barlow said. "We can see dune-like structures and the hollows that occur in the outer deposit."
Barlow told HNGN that pedestal craters (a "crater perched on a plateau elevated above the surroundings") may actually be eroded LARLE craters.
"Several models have been put forth to explain how this plateau is "armored" against erosion, including excess amounts of impact melt and sintering of surface materials by a thermal blast wave created during crater formation," Barlow told HNGN.
Barlow said models exhibiting "salts transported upward by water in the LARLE layer and subsequent formation of a cemented layer ('duricrust')" and salts concentrated on the surface could help explain the preservation of both the LARLE layer and the pedestal craters.
Barlow hopes to complete her catalogue of craters withing the year, and looks forward to running into more mysteries like LARLEs along the way, the press release reported.
"That's part of the fun of science, to see something and say, 'Whoa, what's that?' " she said in the statement. "Projects like this end up leading to proposals."
