Messenger snaps build stunning colour globe of Mercury
Sen—Scientists working with NASA's Messenger probe have produced a global colour map of the surface of Mercury, closest planet to the Sun.
Thousands of sets of images were enhanced then stitched together in a mosaic to create a detailed image covering the entire planet. What they reveal has revolutionised our understanding of Mercury.
The images were taken with the spacecraft's Wide Angle Camera, part of the Mercury Dual Imaging System. The colours are enhancements to the planet's actual subtle hues and represent different surface characteristics, including compositional differences between features. They also reveal how long they have been exposed on the surface.
Rays from young, fresh impact craters appear light blue or white. Medium and dark-blue areas represent "low-reflectance" material in Mercury's crust, believed to be rich in a dark, opaque mineral.
Tan areas are plains formed by the eruption of highly fluid lavas. The large circular, yellowish area above center is a massive impact scar, the Caloris basin. Its interior is filled with smooth, somewhat younger volcanic plains. Small orangish spots are materials deposited by explosive volcanic eruptions.
Messenger, which was launched on August 3, 2004, from Cape Canaveral, Florida, performed three flybys of Mercury in 2008 and 2009 before finally going into orbit in March 2011.
During the one-year primary mission, the spacecraft acquired 88,746 images and considerable further data. It is now in a year-long extended mission, and aiming to acquire more than 80,000 more images to boost our knowledge of Mercury further.
Mercury, which with a diameter of 4,880 km is about a third the size of Earth, had previously only been visited by one spaceprobe, NASA's Mariner 10 in the 1970s.
An artist's impresson of the Messenger spacecraft surveying Mercury. Credit: NASA
Messenger found that Mercury is a dynamic world with a rich history of volcanism, ice at the planet's poles, its own magnetic field, a tenuous atmosphere and the surprising presence of volatiles such as potassium and sulphur.
The latest Messenger results were presented at the annual meeting of the American Association for the Advancement of Science (AAAS) in Boston by Dr David Blewett, of the Johns Hopkins University Applied Physics Laboratory.
His team is looking for a further mission extension to be granted by NASA. Given the astonishing success so far, approval seems a certainty.
The European Space Agency (ESA) in a joint project with the Japanese space agency, JAXA, is meanwhile building its own mission to Mercury. BepiColombo will be launched by an Ariane 5 rocket in 2015 and two separate probes it carries will go into orbit around Mercury in January 2022.