The Mars 101 Section was written by Laurie Schmidt, freelance science writer, and Peter Smith, Phoenix Mission Principal Investigator. The following people were instrumental in helping Laurie and Peter write this section: Richard Alley, Pennsylvania State University; David Catling, University of Washington; David Crown, Planetary Science Institute; William K. Hartmann, Planetary Science Institute; Peter Lanagan, Lunar and Planetary Laboratory; and Ted Scambos, National Snow and Ice Data Center