NASA’s MESSENGER probe will be taking a second flyby past Mercury for the second time this year, on October 6, as part of the sequence of three flybys in its mission, the first of which took place in January 2008. The next flyby is scheduled for next year, in September, before MESSENGER will go into orbit around the planet in 2011.

Next week's encounter will take MESSENGER 125 miles, or 200 kilometers, above the planet’s surface, where the probe is expected to take 1,278 pictures, as well as collect critical data on our solar system’s innermost planet.

During the January flyby, MESSENGER revealed striking similarities between Mercury and Moon’s surface, and gave birth to new theories about the planet’s core, which was believed to have cooled a long time ago.

MESSENGER data suggested that Mercury, which has the largest core compared to the other planets in our solar system, did not have what scientists believed to be a relic core, bur rather an active core powering the planet’s magnetic field.

Before MESSENGER, Mariner 10 was the first and only probe to ever visit Mercury, in 1974 and 1975. Mariner was scheduled to make three flybys, however, every time, the spacecraft captured images of the same side of the planet, and until MESSENGER, scientists had no images of the other side of Mercury.

On this October close-up, MESSENGER will use the instruments onboard to gather more details on the planet’s surface, crust, atmosphere and magnetic field. Furthermore, this flyby will prepare Mercury for the March 2011 mission, when it will enter Mercury’s orbit.