Dark Material on Mercury
As the MESSENGER spacecraft moved northward during the first orbit for which images were acquired, the WAC captured this image. The bright rays from Hokusai can be seen extending across this image, but also clearly visible near the center of this image is a small patch of material that is considerably darker than the surrounding terrain. Other locations with dark material have been spotted across Mercury's surface, including the floor of Hemingway crater, as a halo surrounding Derain, as rays from Matabei, and near some craters in Caloris basin. What is this dark material? Likely it is due to a dark type of rock on Mercury's surface, but there is not currently enough information to identify the type of rock. However, with MESSENGER now in orbit, that situation will soon change, as MESSENGER's orbital science campaign will provide unprecedented chemical information about the rock types on Mercury's surface.
Date acquired: March 29, 2011
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington