A new study has challenged the 2018 discovery of reflections beneath Mars' south polar ice cap, initially thought to be an evidence of a subsurface lake.
Water under Mars surfaceThe initial excitement stemmed from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS), which detected reflections from 1.5 kilometres underground, spanning an area of 20 kilometres.
These signals suggested a buried lake of liquid water, potentially a few centimetres deep.
These layers could cause radar waves to constructively interfere, mimicking the signal expected from a subsurface lake.
The red planets' extreme cold, especially at the poles, casts further doubt on the presence of liquid water, even with high salinity.
A new study has challenged the 2018 discovery of reflections beneath Mars' south polar ice cap, initially thought to be an evidence of a subsurface lake. This revelation, once considered a potential hotspot for extraterrestrial life, now appears less likely given the new analysis.
Water under Mars surface
The initial excitement stemmed from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS), which detected reflections from 1.5 kilometres underground, spanning an area of 20 kilometres. These signals suggested a buried lake of liquid water, potentially a few centimetres deep.
Subglacial lakes on Earth and the presence of barrier-like ice and dust on Mars fuelled speculation that such a lake could exist without evaporating.
However, recent research led by Dr Daniel Lalich from Cornell University suggests that these reflections could be produced by layers of dusty ice with small variations in composition and spacing. These layers could cause radar waves to constructively interfere, mimicking the signal expected from a subsurface lake. This study has been published in Science Advances.
"I can't say it's impossible that there's liquid water down there, but we're showing that there are much simpler ways to get the same observation without having to stretch that far, using mechanisms and materials that we already know exist there," said Dr Lalich in a statement.
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"Just through random chance you can create the same observed signal in the radar."
Previously too, experts have raised questions on the presence of water on Mars. The red planets' extreme cold, especially at the poles, casts further doubt on the presence of liquid water, even with high salinity. Previous theories about carbon dioxide ice or clay also failed to match the MARSIS data.
