Mars, like Earth, appears to have experienced global climate changes over the past few million years. The effects of Earth's ice ages are well recorded in polar ice in Greenland and Antarctica. Similarly, layered deposits in both polar regions on Mars (see Figure 1) appear to record ancient Martian climate variations. Changes in the tilt (relative to the Sun) of the rotation axes of both Earth and Mars are thought to have influenced their climates, but these changes were larger in the Martian case. For this reason and because of the apparent lack of recent oceans and life on Mars, it should be simpler to determine the causes and history of climate changes on Mars. HiRISE has the potential to return images of the polar layered deposits on Mars that will help to unravel Mars' climate history.
Most Mars researchers believe that the polar layered deposits are the result of variations in the amounts of dust and water ice deposited over many climate cycles, but their composition is poorly constrained. In addition, the amount of time needed to form individual layers remains a major uncertainty. Studies of the thickness of polar layers are limited by image resolution. Are thinner layers present, but not visible in the available images? HiRISE is expected to answer this question and better determine the thickness of layers in the polar deposits. Analysis of HiRISE data should result in a better understanding of the timescales involved in the deposition of the layered deposits and provide important information regarding the climate history of Mars.
MGS Mars Orbiter Camera image M03-03597
of the south polar layered deposits.
Resolution = 8.5 m/pixel, illumination from bottom.
(Click for larger version.)