page_title: Phoenix (spacecraft)
section_title: Meteorological station
hierarchical_section_title: Phoenix (spacecraft) / Scientific payload / Meteorological station
caption_attribution_description: English: The Evolution of Dust over the Phoenix Lander
context_page_description: Phoenix was a robotic spacecraft that landed on Mars on May 25, 2008 and operated until November 2. Its instruments were used to assess the local habitability and to research the history of water on Mars. The mission was part of the Mars Scout Program; its total cost was about US$386 million, including launch costs. or $420 million
  The multi-agency program was led by the Lunar and Planetary Laboratory at the University of Arizona, with project management by NASA's Jet Propulsion Laboratory. Academic and industrial partners included universities in the United States, Canada, Switzerland, Denmark, Germany, the United Kingdom, NASA, the Canadian Space Agency, the Finnish Meteorological Institute, Lockheed Martin Space Systems, MacDonald Dettwiler & Associates and other aerospace companies. It was the first NASA mission to Mars led by a public university.
  Phoenix was NASA's sixth successful landing on Mars, from seven attempts, and the first in Mars' polar region. The lander completed its mission in August 2008, and made a last brief communication with Earth on November 2 as available solar power dropped with the Martian winter.
context_section_description: The Meteorological Station (MET) recorded the daily weather of Mars during the course of the Phoenix mission. It is equipped with a wind indicator and pressure and temperature sensors. The MET also contains a lidar (light detection and ranging) device for sampling the number of dust particles in the air. It was designed in Canada by Optech and MDA, supported by the Canadian Space Agency. A team initially led by York University's Professor Diane Michelangeli until her death in 2007, when Professor James Whiteway took over, oversaw the science operations of the station. The York University team includes contributions from the University of Alberta, University of Aarhus (Denmark), Dalhousie University, Finnish Meteorological Institute, Optech, and the Geological Survey of Canada. Canadarm maker MacDonald Dettwiler and Associates (MDA) of Richmond, B.C. built the MET.
  The surface wind velocity, pressure, and temperature were also monitored over the mission (from the tell-tale, pressure, and temperature sensors) and show the evolution of the atmosphere with time. To measure dust and ice contribution to the atmosphere, a lidar was employed. The lidar collected information about the time-dependent structure of the planetary boundary layer by investigating the vertical distribution of dust, ice, fog, and clouds in the local atmosphere.
  There are three temperature sensors (thermocouples) on a 1 m vertical mast (shown at left in its stowed position) at heights of approximately 250, 500 and 1000 mm above the lander deck. The sensors were referenced to a measurement of absolute temperature at the base of the mast. A pressure sensor built by Finnish Meteorological Institute is located in the Payload Electronics Box, which sits on the surface of the deck, and houses the acquisition electronics for the MET payload. The Pressure and Temperature sensors commenced operations on Sol 0 (May 26, 2008) and operated continuously, sampling once every 2 seconds.
  The Telltale is a joint Canadian/Danish instrument (right) which provides a coarse estimate of wind speed and direction. The speed is based on the amount of deflection from vertical that is observed, while the wind direction is provided by which way this deflection occurs. A mirror, located under the telltale, and a calibration "cross," above (as observed through the mirror) are employed to increase the accuracy of the measurement. Either camera, SSI or RAC, could make this measurement, though the former was typically used. Periodic observations both day and night aid in understanding the diurnal variability of wind at the Phoenix landing site.
  The wind speeds ranged from 11 to 58 km/h. The usual average speed was 36 km/h.
  The vertical-pointing lidar was capable of detecting multiple types of backscattering (for example Rayleigh scattering and Mie Scattering), with the delay between laser pulse generation and the return of light scattered by atmospheric particles determining the altitude at which scattering occurs. Additional information was obtained from backscattered light at different wavelengths (colors), and the Phoenix system transmitted both 532 nm and 1064 nm. Such wavelength dependence may make it possible to discriminate between ice and dust, and serve as an indicator of the effective particle size.
  The Phoenix lidar's laser was a passive Q-switched Nd:YAG laser with the dual wavelengths of 1064 nm and 532 nm. It operated at 100 Hz with a pulse width of 10 ns. The scattered light was received by two detectors (green and IR) and the green signal was collected in both analog and photon counting modes.
  The lidar was operated for the first time at noon on Sol 3 (May 29, 2008), recording the first surface extraterrestrial atmospheric profile. This first profile indicated well-mixed dust in the first few kilometers of the atmosphere of Mars, where the planetary boundary layer was observed by a marked decrease in scattering signal. The contour plot (right) shows the amount of dust as a function of time and altitude, with warmer colors (red, orange) indicating more dust, and cooler col
caption: Contour plot of second lidar operation. The colors show evolution of dust passing overhead with time (red/orange: more dust, blue/green: less dust)
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