Scientists are rediscovering the uncharted terrain of Mercury, including ridges that run hundreds of miles and a unique feature made up of more than 100 troughs radiating in all directions, while studying new data and images of the planet.
The new images were captured by the National Aeronautics and Space Administration's Maryland-built Messenger spacecraft that zipped past the solar system's smallest and closest planet to the Sun.
''This flyby allowed us to see a part of the planet never before viewed by spacecraft, and our little craft has returned a gold mine of exciting data,'' Messenger's chief investigator from the Carnegie Institution of Washington, Sean Solomon, said.
''From the perspectives of spacecraft performance and manoeuvre accuracy, this encounter was near-perfect, and we are delighted that all of the science data are now on the ground,'' the New York Times quoted him as saying.
Investigators found Mercury a very dynamic planet, with active volcanos and magnetosphere. The craft discovered an odd feature that scientists dubbed as 'the spider'-- more than 100 narrow, flat-floored troughs radiating from a complex central region never before seen on either Mercury or the moon. The crust of the planet appears to have been pushed upward and cracked from a central point, like a pane of glass.
It is, however, not clear whether that crater was related to the original formation or came later. About 55 per cent of the planet's surface, half of which is always facing the sun, is unknown.
The images and data provided a topographic profile of craters and other geological features on Mercury's dark side, NASA said.
Messenger would fly by Mercury two more times, in October 2008 and September 2009, before returning for a final sweep in 2011 when it would enter its orbit for a year-long study of the planet.
