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.

WASHINGTON, Oct. 29 (Xinhua) -- The latest data captured by a U.S. spacecraft in its second probe this year has revealed more previouslyunseen real estate on the innermost part of Mercury, the U.S. National Aeronautics and Space Administration (NASA) announced Wednesday.

The Mercury Surface, Space Environment, Geochemistry and Ranging, or MESSENGER, spacecraft flew by Mercury, have sent back over 1,200 high-resolution and color images of the Mercury and found another 30 percent of the planet's surface that had never before been seen by spacecraft, said a press release of NASA.

The probe has produced several science firsts and returned more measurements of the planet's surface, atmosphere and magnetic field.

"The region of Mercury's surface that we viewed at close range for the first time this month is bigger than the land area of South America," Sean Solomon, principal investigator and director of the Department of Terrestrial Magnetism at the Carnegie Institution of Washington, was quoted as saying.

"When combined with data from our first flyby and from Mariner 10, our latest coverage means that we have now seen about 95 percent of the planet."

The spacecraft's cameras snapped more than 1,200 pictures of the surface, while topography beneath the spacecraft was profiled with a laser altimeter, allowing scientists, for the first time, to correlate high-resolution topography measurements with high-resolution images.

The spectrometer aboard MESSENGER observed Mercury's thin atmosphere, known as an exosphere. The instrument searched for emissions from sodium, calcium, magnesium and hydrogen atoms.

Observations of magnesium are the first detection of this chemical in Mercury's exosphere. Preliminary analysis suggests that the spatial distributions of sodium, calcium, and magnesium are different.

Simultaneous observations of these spatial distributions, also a first for the spacecraft, have opened an unprecedented window into the interaction of Mercury's surface and exosphere.

The comparison of magnetosphere observations from the spacecraft's first flyby in January with data from the probe's second pass has provided key new insight into the nature of Mercury's internalmagnetic field and revealed new features of its magnetosphere, the volume surrounding Mercury that is controlled by the planet's magnetic field.

"The previous flybys by MESSENGER and Mariner 10 provided data only about Mercury's eastern hemisphere," Brian Anderson, a scientist was quoted as saying.

"The most recent flyby gave us our first measurements on Mercury's western hemisphere, and with them we discovered that the planet's magnetic field is highly symmetric," said Anderson.