The NASA spacecraft MESSENGER this week sent back the first close-up images of Mercury, the solar system's smallest and innermost planet, since the 1973-75 Mariner 10 mission. MESSENGER came as close as 124.6 miles (200.6 kilometers) to the sun-scorched planet on January 14, 2008, during the first of three scheduled flybys before the craft's expected entry into orbit in 2011. Along the way it captured dozens of images of Mercury's sunlit side that had been hidden from Mariner 10, the first and until now only craft to visit the planet. This photo, taken from a distance of about 5,800 kilometers (3,600 miles), reveals a long scarp, or cliff, curving from the top left of the image down to the right, interrupted by an impact crater in the top center. The imaged region is around 170 kilometers (100 miles) across.