comprises a scanning LIDAR, a temperature (T) sensor, and
a pressure (P) sensor. MET will provide data for characterizing
Mars' present climate and weather processes at the landing
site. The LIDAR provides data on the Martian PBL depth;
the location, structure, and optical properties of clouds,
fogs, and dust plumes within the PBL; and some wind data.
The structure and evolution of the Martian PBL is key to
understanding surface atmosphere interactions, particularly
the exchange of volatiles. The LIDAR can probe the Martian
atmosphere up to 20 km altitude. Data obtained from this
height will complement the data obtained by MET's collocated
pressure and temperature sensors. LIDAR observations of
the formation, duration, and movement of clouds, fog, and
dust plumes will improve the modeling of atmospheric processes.
MET LIDAR can pan and tilt, allowing it to point in various
directions. The requirement for MET location on the deck
ensures that the LIDAR has a clear field of view of at least
100 mrad about the beam axis. Temperature will be measured
with thin wire thermocouples, a technology that also has
substantial Martian flight heritage. MET thermocouples will
be mounted on a polyamide frame that provides electrical
insulation, low thermal expansion, strength, and rigidity.
The thermocouples will have a small diameter (0.75 µm)
to reduce frame conduction, velocity errors, and radiative
errors. Chromel constantan thermocouples (Type E) with triple
redundant, insulated, gold-plated junctions reduce thermal
MET pressure sensor is a Tavis P4, a device similar to the
successful sensors used by the Viking and Mars Pathfinder
landers. The sensor's analog output will be converted to
two digital pressure scales. One scale, ranging from 0 to
14 h Pa, will allow a zero-setting verification during cruise.
A second nominal pressure scale, ranging from 9 to 14 h
Pa, will maximize the pressure resolution once Phoenix is
on the surface. The Tavis P4 measurement accuracy is ±9
Pa. lander electronics function as a backup software system
test laboratory (STL). Special test cells for TEGA and MECA
will test sample delivery.