US-Space/ Planet Mercury full of surprises, scientists say

Jun 16, 2011, 19:49 GMT

Washington - An ongoing survey of the planet Mercury shows that the planet closest to the sun is far from the boring rock many thought it was, scientists said Thursday.

NASA's Messenger mission is the first spacecraft to orbit the rocky planet and the data it has collected since March is both verifying and disproving preconceptions about Mercury. On Monday, the probe logged one Mercury-year in orbit, or 88 days, said principle investigator Sean Solomon.

'The biggest misconception (about Mercury) was that we wouldn't be surprised,' Solomon said.

There had been a long-running misconception that Mercury was similar to the moon, but the early observations by Messenger show it is quite different.

'What we are finding is that a lot of the original ideas about Mercury are just plain wrong,' said scientist Larry Nittler of the Carnegie Institution of Washington. 'What's clear is that Mercury is not the moon and is not the Earth.'

The Mariner 10 mission in the 1970s had taken snapshots of Mercury as it flew by, and Messenger mission had also conducted fly-bys. But no craft had ever taken such a long, close look at the planet.

Among the early observations, are photographs of broad plains that are likely the result of suspected volcanic activity and that are nearly half the size of the continental United States, said researcher Brett Denevi of Johns Hopkins University's Applied Physics Laboratory.

The chemical makeup and magnetic field of the planet are also different that expected.

Topographic mapping of the planet shows that deep craters near the poles that had long been thought capable of harboring water ice are in fact deep and shadowy enough to do so.

It is still far too early to tell whether there is, in fact, water on the planet, but finding out will be among the goals of the rest of the mission. If water does turn out to be present, the quantity would likely be greater than on the on the moon given the number of craters and the area that they cover, Solomon said.

Scientists believe that looking at Mercury will provide new ideas about how rocky, Earth-like planets form and develop under different conditions and about how the solar system developed.