The role of particulate scattering in the Earth's radiative balance is a matter of vital concern to the health of the terrestrial atmosphere and ecosystem and consequently a matter of great interest to atmospheric research. The Martian atmosphere has the potential for serving as a laboratory for the terrestrial atmosphere. Its dust atmosphere provides a limiting case for Terrestrial atmospheres, one in which molecular scatter contributes much than particulate scattering to the transfer of radiation through the atmosphere. The Martian atmosphere offers the possibility of distinguishing the roles of dust and ice (both water and carbon dioxide) clouds in radiative forcing, in relative isolation from molecular and organic aerosol contributions. The study of water vapor between the Martian regolith and atmosphere is also naturally compared to similar processes in the Earth's polar regions.

The Phoenix Scout Mission is presently scheduled for launch in 2007, with landing scheduled for June 2008. Phoenix includes MET, a meteorological station, provided by the Canadian Space Agency and presently including lidar, pressure and temperature sensors. The MET station is to provide insight into local Martian weather, complementing digging activities in which evidence of water is sought and thus providing a more comprehensive understanding of the local Martian environment as the search for water is undertaken. Lidar provides unique capabilities in this respect, helping to remotely detect, range and help characterize Martian atmospheric scatterers, including clouds. In this paper, the Phoenix MET lidar concept is described, as are the scientific goals for the lidar instrument. Modeling results, indicating the expected performance of the MET lidar, are presented and discussed. A flight-like field test unit, designed to more fully explore instrument performance in the Martian environment is also described, as well as various field tests relevant to better definition of MET lidar operation on Mars.