Ice at the Equator

On the Victoria Crater lies a "bathtub ring", which is currently being studied by the rover Opprotunity. Spirit has climbed onto a volcanic plateu not that far away from it's landing site. Radar sounding on Mars has brought up the possibility that Mars may be harboring a volume of water that is equal to polar ice cap. The Medusae Fossae Formation located in a hilly area towards the Martian equator has been believed to be made of volcanic ash. They have seen the Martian surface under the sediment. They sent a radar echo through the sediment and found a formation that is similar to frozen water. They say if there is ice at the equator of Mars it is buried several meters below the surface, due to the water vapor pressure on Mars being so low that any ice near the surface would evaporate.