P13F-01
The Phoenix Mission Explores the Martian Arctic
After a thrilling landing on May 25, 2008, Phoenix has conducted a series of science experiments designed to
unlock the secrets of the northern, ice-rich plains. The overarching goals are to determine the history of the
water ice, to check for the signatures of a habitable zone, and to monitor the polar weather from Summer to
late Fall. These goals are achieved in three ways: geologically with cameras and a robotic arm to image and
interact with the surface, analytically using three instruments on the deck to assess the chemistry and
mineralogy of samples, and observationally using a powerful weather station operating around the clock.
Phoenix landed on the fluidized ejecta from the nearby Heimdal crater where the surface is molded into
polygonal shapes characteristic of icy polar terrain. After trenching several inches beneath the surface to an
ice table and examining samples from each layer, samples from different depths were collected and studied.
The chemistry is alkaline with calcium carbonate associated with the ice; this is very different from the
sulfate-rich acidic soil seen by the MER rovers. A surprisingly large amount of perchlorate, likely magnesium
perchlorate, is seen in the wet chemistry lab. Microscopic images reveal three classes of soil particles: iron-
rich clay-sized particles with larger grains of two types. These are compared with the phyllosilicates and
carbonates discovered in the TEGA experiment. The transition of the seasons is recorded in the detailed
data sets collected with our weather station. Ice clouds and ground fogs are evident with frost in the coldest
areas late at night. Taken together a new understanding of the complex interaction of atmosphere, dry soil,
and ice is revealed.
http://phoenix.lpl.arizona.edu