NASA Space Probe to Fly Over Mercury, Closest Planet to Sun:


A U.S. spacecraft will fly over Mercury next week to photograph the planet closest to the sun, in the second of three passes, NASA said.

The Messenger probe will take more than 1,200 pictures and collect data from the smallest planet in the solar system when it swings 125 miles (200 kilometers) above Mercury's cratered surface on Oct. 6, the National Aeronautics and Space Administration said a statement on its Web site yesterday.

The 2,442-pound (1,107 kilogram) probe is due to pass the planet three times before settling into orbit in March 2011, NASA said. Messenger was launched in August 2004 at a cost of $286 million. It first flew past in January and will make its final pass in September 2009.

``The results from Messenger's first flyby of Mercury resolved debates that are more than 30 years old,'' Sean Solomon, the mission's principle investigator from the Carnegie Institution of Washington, said in the statement. ``The second encounter will uncover even more information about the planet.''

The spacecraft is more than halfway through a 4.9 billion- mile journey that includes more than 15 trips around the sun before entering orbit around Mercury, NASA said. The probe is designed to improve scientists' understanding of how Earth, Venus and Mars were formed, and their interactions with the sun.

The January flyby showed that volcanic eruptions produced many of Mercury's plains and that its magnetic field appears to be generated in a molten iron core, according to the space agency.

The second flyby may bring more information about the particles located around the planet's magnetic field, according to NASA, which said the probe will also chart Mercury's topography.

has a diameter of about 3,000 miles, less than half the diameter of Earth and is 36 million miles from the sun.

Before Messenger, the only other craft to visit Mercury was Mariner 10, which passed the planet three times in 1974 and 1975.