An image of the planet Mercury, made during the January 2008 flyby of the planet by the Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) spacecraft is seen in this image released by NASA July 3, 2008. The image shows that volcanoes were involved in plains formation and suggest that its magnetic field is actively produced in the planet's core. (Xinhua/Reuters File Photo) Photo Gallery>>>

    WASHINGTON, Oct. 6 (Xinhua) -- NASA spacecraft MESSENGER has successfully made the second of the three planned flybys of Mercury on Monday, taking pictures of most of its remaining unseen surface.

    The spacecraft passed 125 miles (about 200 km) above the planet's cratered surface, capturing more than 1,200 pictures and collecting a variety of science data.

    Mission scientists hope to begin receiving the new data from MESSENGER in the very early morning on Tuesday.

    "The results from MESSENGER's first flyby of Mercury (on Jan. 14) resolved debates that are more than 30 years old," said Sean Solomon, the mission's principal investigator from the Carnegie Institution of Washington. "This second encounter will uncover even more information about the planet."

    During the spacecraft's first flyby on Jan. 14, its cameras returned images of approximately 20 percent of Mercury's surface never before seen by space probes. Images showed that volcanic eruptions produced many of Mercury's plains, its magnetic field appears to be actively generated in a molten iron core, and the planet has contracted more than previously thought.

    "This second flyby will show us a completely new area of Mercury's surface, opposite from the side of the planet we saw during the first," said Louise Prockter, instrument scientist for the spacecraft's Mercury Dual Imaging System at the Johns Hopkins University Applied Physics Laboratory.

    The second flyby is expected to yield more surprises about the unique physical processes governing Mercury's atmosphere, as well as additional information about the charged particles located in and around Mercury's dynamic magnetic field. An altimeter on the spacecraft will measure the planet's topography, allowing scientists, for the first time, to correlate high-resolution topography measurements with high-resolution images.

    The second flyby also provided a critical gravity assist needed for the probe to become, in March 2011, the first spacecraft to orbit Mercury.

    Now, the spacecraft is more than halfway through a 4.9-billion-mile (about 7.9 billion km) journey to enter orbit around Mercury. In addition to flying by Mercury, the spacecraft flew past Earth in August 2005 and past Venus in October 2006 and June 2007.