Revealing origin and evolution of planet Mercury

Washington, May 1 (ANI): Scientists, using multispectral images obtained from the Messenger spacecraft, are trying to reveal the origin and evolution of the planet Mercury.

Mercury's interior is thought to generally resemble that of the Earth and Mars. However, Mercury's core is anomalously large leading to it sometimes being called the iron planet.

With its ancient craters and smooth plains both covered in a fine-grained gray soil (or regolith), the surface of Mercury superficially resembles the surface of the Moon.

Unlike Earth's crust, which is constantly changing and evolving due to processes such as plate tectonics, the crust is relatively static on the Moon and Mercury.

The bulk of Mercury's crust formed long ago and preserves a record of early events that shaped it and the subsequent forces that modified it.

"Mercury's surface tells us something fundamental about how the planet formed and evolved," said Brett Denevi, a postdoctoral research associate in the School of Earth and Space Exploration at Arizona State University.

"Some of the little evidence that we had prior to MESSENGER seemed to indicate that the composition of Mercury's crust was similar to that of the Moon, leading to the presumption that it had formed in the same manner, with any volcanism that may have occurred being only a secondary component," she said.

While the highlands on the Moon are thought to have formed as the result of a global magma ocean, where less dense minerals floated to the surface to form the crust, evidence now points to a mercurian crust that formed in a manner more similar to the crust of Mars than to that of the Moon.

Denevi's research confirms that volcanism on Mercury was widespread, visible across nearly the entire planet, and that much of the crust may have formed in repeated volcanic eruptions.

Denevi, the lead author on the paper, processed and analyzed the images and spectra.

To help determine how much of Mercury's surface was comprised of smooth plains, she constructed maps by observing overlapping and abutting relations of different landforms.

Denevi also compared spectra of Earth and lunar rocks and soils to constrain the maximum amounts of iron- and titanium-bearing minerals that could be on the surface.

Through mapping of the major geologic terrain types, Denevi and her colleagues distinguished three major terrain types on Mercury: smooth plains, intermediate terrain and low-reflectance material (LRM).

"Of the three, smooth plains are a key terrain type," she said. "The smooth plains cover approximately 40 percent of the surface, and the majority is probably of volcanic origin," she added. (ANI)