Mercury's unseen side is revealed

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Mercury's unseen side is revealed
This image was taken 80 minutes after closest approach Images of Mercury The first pictures taken by the Messenger probe as it passed Mercury on Monday have started to arrive at Earth. They include images that show parts of the surface missed by the Mariner 10 spacecraft when it flew by the planet in the 1970s. Like the previously mapped portions of Mercury, the new sections appear heavily cratered. Messenger needs to perform another two fly-bys and a number of engine firings to get itself into orbit in 2011. Monday's manoeuvre took the probe to within just 200km (125 miles) of the planet at closest approach. Messenger was programmed to collect more than 1,300 images and make other observations during the encounter. The data began transmission to Earth on Tuesday. Enlarge Image This image was taken just 21 minutes after closest approach. Messenger's Narrow Angle Camera spies a variety of surface features, including craters as small as about 300m across. Nasa says such detailed close-ups will be used by planetary geologists to study the processes that have shaped Mercury's surface over the past four billion years. The picture shows part of a giant impact crater to the bottom-right. Enlarge Image This Narrow Angle Camera image was obtained about 37 minutes after closest approach to the planet. It shows a previously unseen crater with distinctive bright rays of ejected material extending radially outward from the crater's centre. Resolution in the picture is about 360m per pixel, and the width of the image is about 370km. Monday's flyby has produced a sequence of pictures that will allow scientists to build a high-resolution mosaic of the northeast quarter of the region not seen by Mariner 10.