NASA’s MESSENGER spacecraft, launched in 2004, completed its second flyby of Mercury early Monday morning, passing within 125 miles (200 kilometers) of the planet’s surface and snapping striking photographs of never-before-seen terrain.

MESSENGER (short for MErcury Surface, Space ENvironment, GEochemistry and Ranging) captured more than 1,200 images during its pass, filling in many of the gaps left by Mariner 10, which imaged 45 percent of Mercury’s planetary surface during three flybys in the mid-1970s. The pockmarked planet, the smallest in the solar system (following Pluto’s demotion to the minor, er, dwarf leagues), is difficult to study from ground-based observatories due to its location—it’s the closest to the sun and is often lost in its parent star’s glare.

The spacecraft’s main objective in buzzing Mercury: to obtain a gravity assist as the probe angles to settle into orbit around the planet in 2011. It will be the first spacecraft ever to do so.

Images from the latest flyby are available at the mission Web site.

CREDIT: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington