Accurate pressure observations in the Martian southern polar region: MVACS /MET-P
A.-M. Harri, J. Polkko, T. Siili (Finnish Meteorological Institute /GEO), D. Crisp (NASA /Jet Propulsion Laboratory)
Pressure observations are crucial for the success of the
Meteorology (MET) package for the Mars Volatiles and Climate
Surveyor (MVACS) expected to land on Mars in December 1999
( 
),
nominally to the location 71 
S, 210 W. The initial period of operation may last up to 210
sols. The MVACS/MET experiment will provide the first
surface-based observations of atmospheric pressure,
temperature, wind, and humidity in the southern hemisphere
of Mars and in the polar regions.
The Martian atmosphere goes through a large scale atmospheric pressure cycle due to the annual condensation/sublimation of the atmospheric carbon dioxide. Pressure also exhibits short period variations associated with dust storms, tides and other atmospheric events. A series of pressure measurements can hence tell us about the large scale state and dynamics of the atmosphere. The shorter time scale phenomena are also important in contributing to our understanding of mixing and transport of heat, dust, and water vapor.
The sensing element of the MET-P will comprise four Barocap radiosonde sensors manufactured by the Vaisala Inc. These sensors were space qualified for the Mars-96 Small Stations and Penetrators. The same type of sensors will also fly onboard the Huygens/Cassini as a part of the atmospheric structure instrument.
The characteristics of the seasonal and shorter term
pressure variations anticipated to take place place at the
MVACS landing site, the design of the MET-P instrument and
the predicted performance thereof are discussed.