Droplets seen on the landing struts of the Phoenix Mars Lander could be water, according to a new report.
Images taken of the legs of the lander in the days after its landing on May 28, 2008, show what appear to be drops of liquid.
Over the course of the next Martian month, the drops grew, merged and dripped down the lander's legs, National Geographic News reports.
Study leader and co-investigator Nilton Renno of the University of Michigan told National Geographic News that the substance was probably saline mud that splashed when the lander touched down.
Renno and his team will present their findings next month at the 40th Lunar and Planetary Science Conference.
The mud likely stays liquid in the Martian cold because it contains high levels of perchlorates, a salt that has "properties like the antifreeze used to melt snow here in Michigan," Renno told National Geographic News.
High perchlorate content makes water able to stay in its liquid form in sub-zero temperatures.
The photographs show the substance behaving like liquid water, Renno said.
"As it cooled down toward the end of the mission and we're seeing the formation of frost everywhere, the drops almost disappeared," he said. "This is consistent with [liquid] drops freezing and losing water to the atmosphere as it gets colder."
The droplets also started sliding down the lander's leg, "consistent with ice melting," Renno told National Geographic News.
Harvard University geochemist Nicholas Tosca told National Geographic News that it is possible water exists on Mars, and that in the presence of perchlorate, the planet could support liquid water at temperatures as low as minus 94 degrees Fahrenheit, near the lowest temperature recorded at the lander's legs.
Tosca said Renno's report makes a case for water on Mars, but the cold and high salt content are not likely hospitable to life.
"If you make the case that life could have started on Mars and could be hiding out somewhere," Tosca told National Geographic News, "it's not likely to be in this cold, salty water."