The NetLander atmospheric instrument system (ATMIS): description and performance assessment

The pointwise meteorological observations of the Viking Lander and Mars Pat hfinder as well as the orbital mapping and sounding performed by, e.g., Mar iner 9, Viking Orbiters and the Mars Global Surveyor have given a good unde rstanding of the basic behaviour of the Martian atmosphere. However, the mo re detailed characterisation of the Martian circulation patterns, boundary layer phenomena and climatological cycles requires deployment of meteorolog ical surface networks. The European NetLander concept comprising four well- instrumented landers is being studied for launch in 2005 and operations spa nning at least a Martian year in 2006-2008. The landers are to be deployed to areas in both Martian hemispheres from equatorial regions to low mid-lat itudes. The NetLander atmospheric instrument system (ATMIS) on board each of the la nders is designed to measure atmospheric vertical profiles of density, pres sure and temperature during the descent onto the surface, as well as pressu re, atmospheric and ground temperatures, wind, atmospheric optical thicknes s and humidity through a full Martian year, possibly beyond. The main opera tional objective of this meteorological experiment is to provide a regular time series of the meteorological parameters as well as accelerated measure ment campaigns. Such a data set would substantially improve our understandi ng of the atmospheric structure, dynamics, climatological cycles, and the a tmosphere-surface interactions. The ATMIS sensor systems and measurement approaches described here are base d on solutions and technologies tested for similar observations on Mars-96, Mars Pathfinder, Huygens, and Mars Polar Lander. Although the number of ob servation sites only permits characterisation of some components of the gen eral circulation, the NetLander ATMIS will more than double the number of i n situ vertical profiles (only three profiles - two from Viking Landers and one from Mars Pathfinder - are currently available and as envisioned at th e time of writing, none of the 2001 and 2003 landers ' payloads include ent ry phase measurements of pressure or temperature), perform the first in sit u meteorological observations in the southern low- and mid-latitudes and pr ovide the first simultaneous in situ multi-site observations of the local a nd general circulation patterns, in a variety of locations and terrains. As such, NetLander ATMIS will be the precursor of more comprehensive meteorol ogical surface networks for future Mars exploration. (C) 2000 Elsevier Scie nce Ltd. All rights reserved.