In 2018, scientists made a discovery that could change our understanding of the dry, dusty red ball Mars.
Radar signals that jumped just below the planet’s surface revealed a bright spot, corresponding to nothing more than an underground pool of liquid water. Subsequent research revealed brighter spots, indicating the existence of an entire network of underground lakes.
Revolutionary stuff, isn’t it? Although Mars contains water in the form of ice, so far not a single drop of liquid has been found on our red friend.
There is only one problem. According to a new analysis, it has found dozens of such bright spots, some in areas too cold for liquid water, even brine, which may have a lower freezing temperature than fresh water.
“We don’t know if these signals are liquid water or not, but they appear to be more prevalent than what the original article found,” Planetary scientist Jeffrey Plott said From NASA’s Jet Propulsion Laboratory.
“Either liquid water is flowing under the south pole of Mars, or these signs point to something else.”
The first feature was detected at the south pole of Mars, beneath the ice cap, using the Mars Advanced Radar for Subsurface and Ionospheric Instruments (MARSIS) on the Mars Express Orbiter.
A follow-up search of archived data revealed three more of these lake-like features. MARSIS uses radar signals to probe under the Martian ice cap, which is made up of alternating layers of carbon dioxide and water ice.
We know, through the use of this technology on Earth, what signals signify certain substances.
“Some types of materials reflect radar signals better than others, and liquid water is one of those materials,” planetary scientist Graciella Caparelli of the University of South Queensland in Australia told ScienceAlert.
“So, when the signals from the interior are stronger than those reflected from the surface, we can confirm that we are in the presence of liquid water.
The signals from these underground plates were stronger than the signal from the surface itself, but the area in which they were found was relatively small.
So Aditya Kholer, a planetary scientist at Arizona State University Plott, expanded the research. They drew 44,000 measurements over 15 years from Mars’ data to cover the entire south pole of Mars.
They found dozens of other highly reflective spots, spread out over a larger scale than previously identified. But the surface of some of the new plates was barely about a kilometer (less than a mile) below the surface, in which case temperatures are estimated to be around 210 K (-63 °C or -81 °F).
previous search He discovered that water saturated with calcium and magnesium salts can remain liquid at temperatures as low as 150 K for very long periods of time. We also know that Mars is rich in calcium and magnesium salts as well as sodium. But An article from 2019 was found There is not enough salt to melt the ice at the base of stratigraphic sediments at the south pole of Mars.
They conclude that some form of primary heating is needed, possibly in the form of geothermal activity: volcanism. However, although there is recent evidence of volcanic activity on Mars, it was located at lower latitudes rather than at the poles.
“They discovered that it would take twice the estimated geothermal flow of Mars to maintain this liquid water,” they said. cavity extractor.
“One possible way to get that amount of heat is through volcanoes. However, we have not seen strong evidence of recent volcanic activity in Antarctica, so it seems unlikely that volcanic activity would allow for any groundwater to exist during this period. Region. “
So what are these shiny spots? Well, we don’t know. The team thinks it’s unlikely to be liquid water – but their maps could help figure it out. We now know, for example, that its causes spread across the south pole of Mars.
And if the plates turned out to be liquid water, then the work, according to the researchers, will better understand how it got there.
The search was published in Geophysical Research Letters.