Salty Water May Flow on Mars

The Clues are Strange, Dark Lines, Which Might Provide New Evidence that Life Exists on the Red Planet

by Masha Vodyanik, age 15

    Recent images taken by NASA’s Mars Reconnaissance Orbiter show dark lines in the mid-latitudes of Mars’ southern hemisphere. Scientists think flows of salt-water may have formed these lines. These lines, however, are very rare. Only seven have been observed.  They vary from half a meter to five meters, and could potentially have carried thousands of gallons of water.
    Even though no liquid forms of water have yet been found on Mars, the planet’s surface shows evidence that liquid water might exist. Water in the form of ice has been found on the polar ice caps of Mars, and underneath its surface.  
    The slopes of the Southern hemisphere, photographed by Orbiter, are far enough away from the planet’s equator for ice to be present. Those slopes that face the equator could possibly be warm enough for the ice to melt, causing flowing water to form dark lines. However, if water were actually present on these slope lines, it would evaporate in hours due to the thin atmosphere of Mars. Even with modern instruments, small amounts of water are hard to detect.
    Scientists have looked into other explanations other than water, for the existence of these lines. They considered carbon dioxide, but temperatures on Mars are too high for this gas to exist in the form of frost. On the other hand, temperatures are too low for freshwater ice to melt and rise to the surface.
    But salt water just happens to stay liquid at lower temperatures than freshwater does. So, the conditions on Mars could be just perfect.  There have been salt deposits found in abundance on the surface, and possible salt-water droplets were detected on the struts of the Phoenix Mars Lander – a robot spacecraft sent to explore the surface of Mars in 2008.
    It has also been suggested that the dark lines are not caused by moisture alone. When water sweeps lighter mineral grains down slopes, it leaves behind rough grains that cast a shadow in the terrains of the surface. The flow lines also end with light color patches that could be deposited minerals left by the flow of the water.
    However, scientists haven’t excluded the fact that the slopes weren’t caused by water at all. Other forces could have caused them, like strong whirlwinds pushing materials downward. Materials flaking off as the ground expands are also a possibility. However, that would be a slow process that would not show such dramatic seasonal changes.
    Scientists once again come back to the possibility of salt water affecting the terrain on Mars. Many researchers are already looking closely at this new study. A planetary scientist at the University of Colorado, Bruce Jakosky, says, “The real thing we need to do is go to places where we think there was liquid water… and bring them back to Earth [to look for] any presence of life.”

[Source: Los Angeles Times]