Article - Mercury Much More Dynamic than Previously Thought

NASA astronomers continue to learn more about Mercury

NASA's Messenger (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft has offered researchers unique glimpses into Mercury that were previously unknown. During an October 6 flyby of Mercury, Messenger learned the small rocky planet has massive impact craters, volcanoes, and magnetic tornadoes. More than 1,200 images were taken during the second Mercury fly by, with researchers getting a glimpse of another 30 percent of the planet's surface.

"This the first time we have seen terrain exposed on the floor of an impact basin on Mercury that is preserved from when it formed," Center for Earth and Planetary Studies research director Thomas Watters said in a statement. "Terrain like this is usually completely buried by volcanic flows."

This is an important find for researchers because ancient impact basins normally are flooded and filled by volcanic flows, though this one has not been the case observed by Messenger. Before the craft flew to the planet, astronomers only speculated about the possibility of craters and volcanoes on the planet's surface.

The Rembrandt crater is more than 430 miles in diameter and could have been created almost 4 billion years ago when a large space rock impacted the planet's surface. Since the crater hasn't been filled in, researchers are interested in studying the planet's volcanic and tectonic activity.

Oddly enough, researchers for a number of years considered Mercury a distant dead planet that offered very little value to the astronomy community. NASA hoped to learn more about the planet -- and change its public view -- when it launched Messenger into space.

It's unknown when NASA plans to have Messenger do another fly by in which thousands of pictures of a select area will be photographed.

All of the findings have been published in several papers published in the May 1 edition of Science.