South Pole of Mars – FLICKR
Nov. 3 () –
Bright reflection signals under the Martian surface have provided further evidence that salty water exists at the base of polar deposits on the Red Planet.
These signals were detected for the first time in data acquired between 2010 and 2019 by the MARSIS radar probe aboard the Mars Express orbiter. Scientists proposed that the reflections pointed to a mosaic of salt lakes, publishing their research in Science in 2018 and in Nature Astronomy in 2021. Recently, a new collaboration provides new evidence that further corroborates this interpretation.
The results of these studies have recently been published in the journals Nature Communications and Journal of Geophysical Research: Planets.
Professor Graziella Caprarelli, from the University of Southern Queensland, said new laboratory experiments and simulations have ruled out alternative interpretations.
“We have explored questions such as ‘is it possible that the strong radar signals could be produced by other types of materials such as clays or saline ice, or by constructive interference’“, said it’s a statement.
“The latest papers address the age-old question of temperatures at the base of the south polar cap: so far, they were considered to be too low even for brines to be liquid.”
Caprarelli, attached to the Center for Astrophysics at the University of Southern Queensland, developed the thermal models and calculated the range of temperatures at the base of Mars’ south polar cap, below the south polar layered deposits (SPLD).
“We decided to study the physical properties of the deposits themselves, modeling the propagation of radar waves through water ice and dust”.
The new calculations limit the percentage of dust inclusions in the deposits between 5% and 12%, and also establish an upper limit of -43 °C for the temperature at the base.
“Our studies show that the temperature at the base of the SPLD calculated so far by other researchers has been greatly underestimated and can instead easily reach -73 °C, which is within the range of melting temperatures of perchlorate brines”, Caprarelli said.
“New laboratory experiments conducted at the Roma Tre University (Italy) and Southwest Research Institute (USA) laboratories further demonstrate that the physical properties of brines at these revised temperatures are fully consistent with the strength of the acquired radar signals from the base of the Martian south polar deposits”.
