Overview

Is there water on Mars? This question has been widely debated by scientists since at least the 18th century when astronomer Giovanni Schiaparelli observed Mars with a telescope and thought he saw canals. Now, a new compelling study points to the presence of a large lake of water beneath Mars’ south polar ice cap. The study sheds new light on the matter, suggesting there could be liquid water on Mars after all.

The science and other stuff to know

In 2018, the European Mars Express orbiter discovered that the surface of the ice cap covering Mars’ South Pole dips and rises, suggesting liquid water may be lurking underneath. However, at the time, not all scientists were convinced. Mars is extremely cold, and for subglacial water to exist on the planet in liquid form, there would have to be a source of heat, such as geothermal energy.

At the time of the Mars Express discovery, some researchers argued that the strange radar signal might be explained by something else, for instance, some sort of dry material below the ice caps. But recently, an international team of scientists led by researchers from the University of Cambridge investigated the ice-sheet-covered region using a different technique and concluded that the presence of liquid water is the likeliest explanation.

Using spacecraft laser-altimeter measurements from NASA’s Mars Global Surveyor satellite to map the topography, or shape, of the upper surface of the ice cap, the researchers detected subtle patterns of height differences that matched computer model predictions for how a body of water beneath the ice cap would affect its surface, according to the study published in the Nature Astronomy journal.

“The combination of the new topographic evidence, our computer model results, and the radar data make it much more likely that at least one area of subglacial liquid water exists on Mars today,” said Neil Arnold, professor at Cambridge Scott Polar Research Institute, who led the study, in a press release.

So what?

While not everyone agrees there’s liquid water on Mars, if it’s proven to exist beneath Mars’ cap, it could spark hope for the existence of hardy microbial life on the Red Planet.

“Liquid water is an essential ingredient for life, although it does not necessarily mean that life exists on Mars,” Frances Butcher, second author of the study, said. “In order to be liquid at such cold temperatures, the water beneath the South Pole might need to be really salty, which would make it difficult for any microbial life to inhabit it. However, it does give hope that there were more habitable environments in the past when the climate was less unforgiving.”

What’s next?

The quality of data returning from Mars, both from orbital satellites and landers, is such that we can use it to answer really difficult questions about conditions on, and even beneath, the planet’s surface. And scientists are using the same techniques they use on Earth.