Mar 17, 2009, 16:40 GMT
Washinton - A group of scientists who worked on the Phoenix Mars lander last year say they have found evidence of liquid salt water on the red planet.
An analysis of photographs from the lander that explored Mars for six months shows drops of what could be salty, liquid water on the legs of the lander.
They believe the droplets were kicked up from just below the planet's surface when Phoenix landed in May and say they grew and merged over time much as water particles would do.
The findings are to be presented in a report, The Physical and Thermodynamic Evidence for Liquid Water on Mars, at an astronomy conference in Texas on Monday.
'A large number of independent physical and thermodynamical evidence shows that saline water may actually be common on Mars,' said the report's chief author, University of Michigan professor Nilton Renno. 'Liquid water is an essential ingredient for life. This discovery has important implications to many areas of planetary exploration, including the habitability of Mars.'
But the evidence is controversial even among scientists who worked on the mission and was never raised by NASA at the time, with some saying there were other more probable explanations. Still 22 scientists have signed onto the report.
Phoenix did confirm the existence of ice on Mars to much fanfare and in the past researchers believed that was the only type of water likely to be found on the planet, where temperatures average about negative 60 degrees Celsius at the rover's landing site.
Renno, a co-investigator on the Phoenix mission, said another discovery by Phoenix - the presence of perchlorate salts - is consistent with liquid water.
The salts could significantly lower the freezing point of water to between negative 67 and negative 75 degrees - much as salt is used in cold climates on Earth to melt ice and snow. Renno said there could be areas across the planet that are too salty to freeze.
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