First portraits of Mercury from orbit

MESSENGER spacecraft to capture more than 1,500 images in three days

NASA’s MESSENGER spacecraft has returned the first images ever taken by a probe orbiting Mercury, the solar system’s innermost planet. Recorded on March 29, the historic closeups show parts of the south and north polar terrain never before viewed by a spacecraft. NASA released the first image taken from orbit on March 29 and several others on March 30.

Some of the new portraits show a surprisingly high number of secondary craters, small pockmarks generated when material excavated by the formation of a larger crater falls back on the surface.

The craft’s cameras will have acquired and sent more than 1,500 images to Earth by March 31. “That’s the barest hint of what we’ll have on a regular basis,” said MESSENGER lead scientist Sean Solomon of the Carnegie Institution for Science in Washington, D.C. By the end of the mission in March 2012, the craft will have taken some 75,000 images that scientists will assemble into a global mosaic of Mercury.

“It’s just thrilling to link this not very bright point of light in the sky” with the close-up portraits now being beamed to Earth by MESSENGER, Solomon said.

All seven of the craft’s instruments have now recorded data, including one that uses the round-trip travel time of laser pulses reflected from the planet to measure the heights of surface features. The craft’s magnetometer has already made more measurements of Mercury’s magnetic field than were taken during six previous flybys by MESSENGER and the Mariner 10 spacecraft.

On March 17, MESSENGER became the first craft to orbit Mercury (SN Online: 3/17/11). The craft’s year-long mission to explore the gravity, magnetic field, atmosphere, surface composition and interior of the tiniest and least-explored planet in the solar system formally begins on April 4.

ZOOMED IN This view of Mercury’s north polar region, recorded by the MESSENGER spacecraft on March 29 from an altitude of about 450 kilometers, shows part of the planet never before imaged up close. NASA, Johns Hopkins University Applied Physics Laboratory, Carnegie Institution for Science

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