May 23, 2009 Despite falling silent late last year after five months on the arctic plains of the Red Planet, scientists around the globe continue to analyze data gathered by the Phoenix lander and uncover more clues in the search for evidence of life on other planets. This latest news comes from researchers at the University of Arkansas who have shown that salts discovered at the Phoenix landing site have the potential to be found as liquid water - an essential ingredient for life - under the temperature and pressure conditions on Mars.

Mars lander

The Phoenix landed on the red planet in March 2008 after a 10 month journey with research being conducted over a 150 day period. Samples and information gathered from this exploration have formed the basis for research into the planet's make up by teams across the globe.

The water of life

The University of Arkansas team led by Prof. Vincent F. Chevrier with graduate students Jennifer Hanley and Travis S. Altheide investigated the properties of sodium and magnesium perchlorates, salt compounds that are are rare on Earth - detected by the Phoenix lander. The studies occurred under the same temperature, pressure and humidity conditions found at the landing site using the Andromeda Chamber in the W.M. Keck Laboratory for Space Simulation. Thermodynamic calculations were undertaken to determine the state of salt and water combinations on the Martian surface and to see if there was any potential for liquid to be found.

Hanley says that under the extreme temperatures on Mars it is difficult to imagine that water could be found in liquid form, as it would typically lead to evaporation or crystallization. However by the same mechanism in which salt is used to melt ice on roads by lowering its freezing point, perchlorate salts lower the freezing point of water substantially. Correspondingly, the temperature for the liquid phase of magnesium perchlorate – 206 degrees Kelvin – is a temperature found for a few hours each day in summer on Mars at the Phoenix landing site, suggesting that this perchlorate solution could be present in liquid form during this time.

The work is the first demonstration of a potential stable liquid on present-day Mars in the immediate environment of the landing and supports the possibility of finding life on Mars.

“Under real, observed Martian conditions, you can have a stable liquid,” said Chevrier. “You don’t necessarily need to have a lot of water to have life, but you need liquid water at some point.”

The group reported their findings recently in Geophysical Research Letters.

David Greig