Martian soil could hold liquid water

Abstract

Javier Martin-Torres of the Lulea University of Technology in Kiruna, Sweden, and colleagues have tracked the weather conditions on Mars throughout Curiosity's first Martian year, recording humidity, air and ground temperatures with its Rover Environmental Monitoring Station. The team found that during the Martian winter, conditions throughout the cold but humid nights would allow liquid water to persist in the first 5 centimeters of the surface. It could also persist for shorter periods in other seasons. They suggest that calcium perchlorate in the ground absorbs water from the atmosphere until it dissolves into a salty solution, or brine. This process is called deliquescence. When the sun comes up and the temperature rises, the water evaporates and returns to the atmosphere, starting the cycle anew