The Thermal and Electrical Conductivity Probe on NASA's Phoenix Mars
Lander detected small and variable amounts of water in the Martian soil.
In this schematic illustration, water molecules are represented in red and
white; soil minerals are represented in green and blue. The water, neither
liquid, vapor, nor solid, adheres in very thin films of molecules to the
surfaces of soil minerals. The left half illustrates an interpretation of
less water being adsorbed onto the soil-particle surface during a period
when the tilt, or obliquity, of Mars' rotation axis is small, as it is in
the present. The right half illustrates a thicker film of water during a
time when the obliquity is greater, as it is during cycles on time scales
of hundreds of thousands of years. As the humidity of the atmosphere
increases, more water accumulates on mineral surfaces. Thicker films
behave increasingly like liquid water.
The Phoenix Mission is led by the University of Arizona, Tucson, on behalf
of NASA. Project management of the mission is by NASA's Jet Propulsion
Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin
Space Systems, Denver.