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Mercury, as seen from orbit

mercury.jpgPosted on behalf of Adam Mann.

Mercury, the solar system’s smallest planet and a font of geophysical enigmas, is now squarely in researcher’s sights. On 29 March, NASA’s MESSENGER spacecraft radioed back the first ever images taken from orbit around Mercury, including never-before-seen portions of the planet’s far southern regions.

“The team is elated and everyone is excited,” says Sean Solomon, a geophysicist at the Carnegie Institution for Science in Washington DC and the mission’s principal investigator.

The first image returned since MESSENGER entered orbit on 18 March prominently features a bright, rayed crater named Debussy, near the planet’s south pole. Of most interest, though are the shadowed craters below Debussy, which may harbor permanent water ice in their bowls, says Solomon. It will take time before the team is able to confirm the presence of ice but the spacecraft’s instruments are now fully operational and acquiring data from the planet’s surface, he adds.

The team is already poring over the 363 other images acquired today, says Solomon, and will next download high-resolution ones taken at the planet’s north pole.

Starting next week, MESSENGER will enter a continuous mapping phase and should be sending back many more photos during its operation. As planned, the spacecraft is currently in its primary science orbit, a highly elliptical near-polar trajectory which is ideal for a planet-wide survey. The orbit brings the spacecraft to its nearest point to Mercury – around 60° north latitude – about once every 12 hours (that same latitude as Mercury’s vast Caloris impact basin). That means northern hemisphere images are likely to reveal more small-scale topographic features than the image shown here. Periodic orbital corrections are planned – with the first scheduled for this June – to keep MESSENGER’s nearest approach to the planet within 500 kilometres of the surface.

“We’re just at the beginning of a flood of new data,” says Solomon.

Previously: NASA mission set to orbit Mercury.

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

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