A Southwest Research Institute scientist measured the properties of ice-brine mixtures as cold as -145 degrees Fahrenheit to help confirm that salty water likely exists between grains of ice or sediment under the ice cap at Mars’ south pole. Laboratory measurements conducted by SwRI geophysicist Dr. David Stillman support oddly bright reflections detected by the MARSIS subsurface sounding radar aboard ESA’s Mars Express orbiter.
With a 130-foot antenna, MARSIS flies over the planet, bouncing radio waves over a selected area and then receiving and analyzing the echoes or reflections. Any near-surface liquid water should send a strong bright signal, whereas the radar signal for ice and rock would be much smaller.
Because conventional models assume the Mars south polar cap experiences temperatures much lower than the melting point of water, many scientists have questioned the presence of liquid water. Clay, hydrated salts and saline ices have been proposed as potential explanations for the source of the bright basal reflections. The Italian-led team investigating the proposed phenomena used previously published data, simulations and new laboratory measurements.
“Lakes of liquid water actually exist beneath glaciers in Arctic and Antarctic regions, so we have Earth analogs for finding liquid water below ice,” said Stillman, a specialist in detecting water in any format — liquid, ice or absorbed — on planetary bodies and co-author of a paper describing these findings. “The exotic salts that we know exist on Mars have amazing ‘antifreeze’ properties allowing brines to remain liquid down to -103 degrees Fahrenheit. We studied these salts in our lab to understand how they would respond to radar.”
Read more at: Southwest Research Institute
An SwRI scientist studied the antifreeze properties of exotic salts that exist on Mars, which could allow brines to remain liquid down to -103 degrees Fahrenheit. The studies show how a mile below the Martian south polar cap, brines between the grains of ice or sediments could produce the strong reflections detected by the radar instrument aboard ESA’s Mars Express orbiter.(Photo Credit: NASA/JPL-Caltech/USGS/SwRI)