But there may be a silver lining to the discovery.
Smectites are a type of clay that forms when volcanic rock (basalt) breaks down in the presence of water.
In other words, the abundant presence of smectite on Mars proves, at the very least, the Red Planet used to be wet.
Briony Horgan, study co-author and professor at Purdue University, said: “Detecting possible clay minerals in and below the south polar ice cap is important because it tells us that the ice includes sediments that have interacted with water sometime in the past, either in the ice cap or before the ice was there.
“So while our work shows that there may not be liquid water and an associated habitable environment for life under the cap today, it does tell us about water that existed in the past.”
The researchers supporter their study with lab tests that simulated the freezing conditions under Mars’s polar caps.