|MRO´ High Resolution Imaging Science Experiment (HiRISE) acquired this image during its first day of test imaging from the spacecraft's low-altitude mapping orbit, Sept. 29, 2006. This image of Mars' north polar layered deposits was taken during the summer season (solar longitude of 113.6 degrees), when carbon dioxide frost had evaporated from the surface. The bright spots seen here are most likely patches of water frost, but the location of the frost patches does not appear to be controlled by topography. Layers are visible at the bottom of the image, mostly due to difference in slope between them. The variations in slope are probably caused by differences in the physical properties of the layers. Thinner layers that have previously been observed in these deposits are visible, and may represent annual deposition of water ice and dust that is thought to form the polar layered deposits. These deposits are thought to record global climate variations on Mars, similar to ice ages on Earth. The image is centered at 86.5 degree latitude, 172.0 degrees east longitude. The image scale is 59.8 centimeters (23.5 inches) per pixel (with two-by-two binning} so objects about 1.79 meters (70 inches) across are resolved.