+ Larger image
Image top: An engineering drawing of the MET mast showing the location of the three thermometers as the yellow, u-shaped devices. Image credit: MET Team/CSA.
built by the Canadian Space Agency
Throughout the course of Phoenix surface operations, MET will record the daily weather of the martian northern plains using temperature and pressure sensors, as well as a light detection and ranging (LIDAR) instrument. With these instruments, MET will play an important role by providing information on the current state of the polar atmosphere and how water is cycled between the solid and gas phases in the martian arctic.
The MET's lidar is an instrument that operates on the same basic principle as RADAR, using powerful laser light pulses rather than radio waves. The lidar transmits light vertically into the atmosphere, which is reflected off dust and ice particles. These reflected light pulses and their time of return to the lidar instrument are analyzed, revealing information about the size of atmospheric particles and their location.
From this distribution of dust and ice particles, scientists can make important inferences about how energy flows within the polar atmosphere, important information for understanding martian weather. These particles also reveal the formation, duration, and movement of clouds, fog, and dust plumes, improving scientific understanding of Mars' atmospheric processes.
The very cold temperatures of the martian arctic will be measured with thin wire thermocouples, a technology that has been used successfully on meteorological stations for both the Viking and Pathfinder missions. In a thermocouple, electric current flows in a closed circuit of two dissimilar metals (chromel and constantan in the case of the MET) when one of the two junctions is at a different temperature. Three of these thermocouple sensors will be located on a 1.2 meter vertical mast to provide a profile of how the temperature changes with height near the surface.
Atmospheric pressure on Mars is very low and requires a sensitive sensor for measurement. Pressure sensors similar to those used on the Viking and Pathfinder missions will be part of the MET.
The Canadian Space Agency is responsible for overall development of the MET. The MET instruments will be built by the MD Robotics of Brampton, Ontario, with the support of Optech Inc. of Toronto for the development of the lidar.