Introduction to the fifth Mars Polar Science special issue: key questions, needed observations, and recommended investigations

The Fifth International Conference on Mars Polar Science and Exploration – which was held from September 12–16, 2011, at the Pike’s Waterfront Lodge in Fairbanks, Alaska – is the latest in a continuing series of meetings that are intended to promote the exchange of knowledge and ideas between planetary and terrestrial scientists interested in Mars polar and climate research (http://www.lpi.usra.edu/meetings/polar2011/polar20113rd.html). The conference was sponsored by the Lunar and Planetary Institute, National Aeronautics and Space Administration, NASA’s Mars Program Office, University of Alaska Fairbanks, International Association of Cryospheric Sciences and the Centre for Research in Earth and Space Sciences at York University.