Citizen Staff Writer
ALAN FISCHER
afischer@tucsoncitizen.com
Salty liquid water may have splashed onto the leg of the Phoenix Mars Lander as it arrived on the planet’s surface.
If true, that could place liquid water, essential for life, on the planet at this time.
The Lander’s thrusters exposed subsurface ice and blasted liquid salt water found above the ice layer onto the struts of the spacecraft’s leg, according to a paper that will be presented at the 40th Lunar and Planetary Science Conference March 23 in Houston.
The Martian temperature ranged from minus 22 degrees Fahrenheit to minus 115 degrees Fahrenheit on the Lander’s first day on the surface, said Andrea Matte, media relations adviser for the Canadian Space Agency, which built and oversaw the spacecraft’s meteoroligical station.
Temperature extremes over the mission were minus 11 degrees Fahrenheit and minus 140 degrees Fahrenheit, Matte said.
Such cold temperatures meant any water there should be frozen.
The Lander’s instruments successfully touched and tasted water ice.
But perchlorate, a salt researchers were surprised to discover on Mars, could in high enough concentrations lower the freezing point of water enough to allow for the liquid form, the paper says.
The Phoenix mission, led by the University of Arizona, landed May 25.
The Lander analyzed ice and soil scooped from the planet’s northern arctic region during five months of surface activity, seeking evidence of water and elements of life that could show the region is or was habitable.
If salty water included 30 to 50 percent perchlorate, it could remain liquid as low as minus 94 degrees Fahrenheit on Mars, said Peter Smith, the mission’s principal investigator.
“It could stay liquid for some time,” Smith said. “I think there is a good chance these things are liquid. You really do see lumps on the strut, and they do change over time. These are observable facts.”
But other explanations for the material photographed on the strut exist, said Smith, senior research scientist at the UA Lunar and Planetary Lab.
The Lander’s thrusters created an artificial environment between the bottom of the spacecraft and the surface of the planet for a few seconds at touchdown, Smith said.
High pressure, high temperatures and the chemistry from the Lander’s exhaust gases, which include ammonia and water, could have interacted with the soil chemistry to produce the water-like material that was visible in photographs of the strut, he said.
“It’s just hard to say,” Smith said. “I just don’t know what those clumps are made of.”
Researchers delivered a scoop of Martian soil likely to be rich in perchlorate to the last of four wet chemistry labs remaining for analysis, but the material failed to enter the device for testing, Smith said.
Had the test shown perchlorate levels greater than 30 percent at the landing site, the liquid salt water conclusion would have been bolstered, he said.
Perchlorate may have blocked researchers from finding organic materials that could have offered evidence of life on Mars, Smith said.
When the Lander’s Thermal and Evolved-Gas Analyzer heated soil and ice samples to check for organics, gases emitted by the perchlorate masked the presence of the organics, he said.
UA researchers are running lab tests on campus to determine which, if any, organics are most likely associated with the ice found at the landing site, Smith said.
Evidence points to liquid water on Mars