Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. As Mars Pathfinder and its mobile robot Sojourner continue to explore Mars , new and interesting rocks are being discovered, even though the primary mission has been successfully completed. The shape and fine-scale textures of Half Dome are still being studied. As part of the extended mission, Sojourner has been sent on its longest journey yet - a 50 meter stroll around the Sagan Memorial Station .
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