Scientists have come across more evidence of salty lakes at the base of the Martian poles. Scientists have ruled out alternative explanations.
Further evidence of salty water beneath Mars’ surface has been provided by bright reflection signatures underneath the surface. MARSIS radar on the Mars Express orbiter detected these signals for the first time between 2010 and 2019. Science published their research in 2018 and Nature Astronomy in 2021, suggesting the reflections were caused by salty lakes. This interpretation has been further corroborated recently by a new collaboration. Recent publications of these studies can be found in the prestigious journals Nature Communications and Journal of Geophysical Research Planets.
Lakes on Mars
A new laboratory experiment and simulation have ruled out alternative interpretations, according to Professor Caprarelli. Scientists explored questions such as “could the strong radar signals have been caused by clay or salt ice, or could they have been caused by constructive interference?” In their latest papers, researchers address a long-standing question regarding the temperatures at the south polar cap, which so far were thought to be too low for brines to be liquid. The thermal models were developed by Professor Caprarelli. Caprarelli is an adjunct professor at the University of Southern Queensland’s Centre for Astrophysics. They were then used to predict the range of temperatures beneath Mars’ south polar cap, beneath the South Polar Layered Deposits (SPLD).
Physical properties
“We decided to study the physical properties of the deposits themselves by modeling the propagation of radar waves through water, ice, and dust.” Furthermore, it was calculated that the percentage of dust inclusions in the deposits ranged between 5 and 12 percent. It further limits the base temperature to 230 K (-43°C). “Our studies show that the temperature at the base of the SPLD computed thus far by other researchers (approximately 170-180 K) have been greatly underestimated and can instead easily reach 200 K (-73°C), which is within range of the melting temperatures of perchlorate brines,” Professor Caprarelli said.
The recent experiments conducted by Roma Tre University (Italy) and Southwest Research Institute (USA) confirm it. Scientists found brines at revised temperatures to have physical properties that are entirely consistent with radar signals obtained from the Martian south polar deposit base.
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