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Is Water Found Below Mars’ South Pole?

Story Highlights

  • MARSIS has observed bright basal reflections at Ultimi Scopuli, Mars.
  • The contrast between the ice and the basal material must be high.
  • Hydrous minerals and salts are being studied as a potential replacement for groundwater.
  • At such a low base temperature, only brines can produce such a high dielectric contrast.

Mars is the fourth planet from the Sun and the most Earth-like planet in our solar system. It is also known as the “Red Planet” because the iron oxide chemicals in its soil look like rust. Mars has seasons, polar ice caps, volcanoes, weather, canyons, and a very thin atmosphere primarily composed of carbon dioxide.  The only confirmed site on Mars where water ice can be found is the north polar ice cap, although there has long been speculation regarding whether there is water in the planet’s south pole. Few studies have been conducted with contradictory results. Indeed, the study from Mattei et al. (2018, 2022) showed that they found evidence of liquid water under the ice in Ultimi Scopuli, a region near the south pole of Mars. On the contrary, other studies by Putzig et al. (2021) showed that instead of liquid water, there could have been clays, metallic minerals, and salty ice at the base of the planet’s polar cap. The problem revolves around reflectance reported by a Mars Express orbiter instrument named (MARSIS).

Fig.1. NASA’s Viking spacecraft captured this image
of Mars from orbit. Image adapted from NASA/JP (2021).  

The device analyses Mars’ subsurface composition and searches for frozen water. In a nutshell, liquid water and frozen water send out distinct signals, with liquid water being more reflective than frozen water. MARSIS data is the basis of Elizabetha Mathei et al paper (2018). announcing the presence of buried liquid water. Detection of water on Mars’ surface, or close to it, shows the existence of more than 21 million  km3 of ice, which would be able to cover the planet with water 35 m (115 ft.) deep, Aghababaei et al. (2022). However, there is some contradiction in this data interpretation. Whereas Mathei et al. (2018) believe that more ice is probably frozen into the profound subsurface, other scientists i.e., Dr Nathaniel Putzig, suggests it is not essential to invoke liquid water at the polar cap’s base to explain the MARSIS observations.

Alternatives to it could include clay, some metallic minerals, and salty ice. Yet, the latest study letter disagrees. The authors acknowledge the counter-explanations for the MARSIS signal, but they also offer counter-counter-explanations. Clays, metallic minerals, and salty ice are discounted as explanations since the dielectric properties of these materials do not generate strong basal reflections at MARSIS frequencies and in the Martian atmosphere. In fact, according to them online brine can generate such strong dielectric contrast at such a low basal temperature.

Based on the scientific evidence discovered thus far, it is unknown whether there are lakes beneath Mars’ south pole. If there is something there, it’ll be more slush than a lake, and it might not be anything like the subterranean lakes on Earth. Scientists and researchers are engaging with the evidence differently and reaching different conclusions.


“Assessing the Role Of Clay And Salts On the Origin Of MARSIS Basal Bright Reflections – ScienceDirect.” ScienceDirect,, 19 January. 2022,

Universe today:“The Scientific Debate Rages On: Is There Water Under Mars’ South Pole? – Universe Today.” Universe Today,, 28 January. 2022,

Encyclopedia: Aghababaei, Mohammad. “Water On Mars | Encyclopedia.” Water On Mars | Encyclopedia,,

This Article is written by Dea Rama
(730 Eglinton Ave W, Toronto, ON M5N 1B9)

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