Setting our sights on Mercury (part 4)

Posted by Rich Talcott
on Wednesday, January 16, 2008

On January 14, NASA’s MESSENGER spacecraft flew past Mercury. MESSENGER — short for MErcury Surface, Space ENvironment, GEochemistry, and Ranging made the first close-up observations of the innermost planet in 33 years. This flyby marked the first of three encounters with the planet, providing gravity assists necessary to place the probe in orbit around Mercury in March 2011.

January 16, 2008

The first close-up images of Mercury have made their way to Earth from the MESSENGER spacecraft, and scientists couldn’t be happier. The stark, crater-pocked landscape shows details never seen before — even though the Mariner 10 spacecraft saw some of the same rugged terrain in the mid-1970s.

The first close-up released by planetary scientists at Johns Hopkins University’s Applied Physics Lab shows the region around the double-ringed crater Vivaldi (named after the Italian composer). The crater, whose outer ring spans 125 miles (200 kilometers), appears deeply shadowed in this view because the Sun lay near the horizon.

Although Mariner 10 imaged this area, the image did not show much of the ancient depression to Vivaldi’s lower left. The impact that created Vivaldi partially destroyed this earlier impact basin. The new image’s outstanding resolution proves we’ll see far more detail in MESSENGER’s images than we did with Mariner 10’s vidicon camera.

MESSENGER started observing Mercury with its full suite of instruments Sunday morning. It skimmed within 125 miles (200 km) of the planet’s equator at 2:05 P.M. EST yesterday, and concluded its observations around noon EST Monday. All told, the cameras took more than 1,200 images of the planet and studied its surface, interior, magnetic field, and thin atmosphere.

This image shows the double-ringed crater Vivaldi (upper right) and its surroundings 56 minutes before the spacecraft’s closest approach to Mercury. At the time, MESSENGER was 11,000 miles (18,000 km) from the planet’s surface. Click here for a larger view.

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