The aridity of Mars' surface is well known. The entire planet is a dry, desolate wasteland made of rock and, in some places, ice, but no liquid water has been detected, hence it is assumed that the planet is a dry desert.
But in 2018, researchers made a startling discovery: they had discovered proof of a massive subsurface reservoir of liquid water on the south pole of Mars.
They've now advanced that discovery significantly. Under the southern polar ice cap, there is not just one lake, but rather a vast network of several lakes. Thus, the initial reservoir was not an anomaly or a peculiarity of Martian nature.
According to geophysicist Elena Pettinelli of Roma Tre University in Italy, "the existence of a single subglacial lake could be attributed to ad-hoc conditions such as the presence of a volcano under the ice sheet, or some other situation specific to the specific location where we found the first subglacial lake." Together with her coworker Sebastian Emanuel Lauro, she oversaw the research.
Instead, the discovery of a vast network of lakes raises the possibility that their genesis was very straightforward and perhaps widespread.
Just a little more than two years ago, the first subglacial lake was disclosed. The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on the Mars Express spacecraft was used to make the discovery.
In order to characterize a topography, radio waves are bounced off a surface, measured as echoes, and used in a similar manner to the way we detect subglacial lakes in Antarctica.
These radar sounding investigations first located a single subglacial lake spanning 20 kilometres (12.4 miles) across, 1.5 kilometres (0.93 miles) beneath the southern polar ice sheet.
Liquid water is one of the "materials" that can reflect radar signals more effectively than other types of "materials," according to one of the researchers, planetary scientist Graziella Caparelli of the University of Southern Queensland in Australia.
"Therefore, we can verify the presence of liquid water when the signals from the subsurface are stronger than those reflected by the surface. The same objective is served by radars on Earth, where we have direct access to the data, proving the validity of the method."
Since then, the team has conducted additional analyses on a dataset that covers the years 2010 through 2019. And they discovered three new brightly reflecting spots after doing a fresh study of those data.
In other words, not far from that first lake, a network of subglacial lakes buried away under the south pole, separated by patches of dry stone.
As far as we are aware, no other physical mechanisms can produce such a strong anomaly. "In a terrestrial subglacial environment, such powerful reflections below the ice are related with the presence of basal water," Pettinelli added.
Importantly, we were able to replicate our 2018 paper's findings using more sophisticated data processing and analysis techniques. This, combined with the fact that we were able to confirm the existence of the lake in question and discover additional lakes, gives us great confidence in our conclusion that the liquid is water.
Furthermore, it's probably salt water if it's liquid. highly salted water. You know, Mars is extremely cold, and despite the fact that its interior is warmer than its exterior, it is still chilly enough to cause freshwater to freeze. The team calculated that the lake they discovered would be approximately 205 Kelvin in 2018. (-68.15 degrees Celsius, or -90.67 degrees Fahrenheit).
But salt can drastically lower the freezing point of water. As the researchers points out in their study, water infused with calcium and magnesium salts can stay liquid for a very long time at temperatures as low as 150 Kelvin. We also know that Mars is abundant in sodium, calcium, and magnesium salts thanks to surface exploration.
Therefore, the discovery of new salty subglacial lakes is crucial. It also indicates that they can last for geologically long epochs and form readily, which is a crucial component in the long-standing riddle of Mars' water and climatic history. Additionally, it has significant ramifications for the search for bacteria on Mars.
Planetary scientist and MARSIS main investigator Roberto Orosei of the National Institute for Astrophysics in Italy stated that "These lakes have probably been present for most of Mars' history."
They might still have remnants of any life forms that might have developed on Mars when it had a thick atmosphere, a temperate climate, and liquid water on the surface, akin to the early Earth.
In certain lakes, it's even conceivable that microbial life is still thriving.
We are aware that such creatures can survive in subglacial reservoirs as well as some of the saltiest, most hostile environments on Earth. We're obviously a very, very long way from making such a discovery, and closely examining the water on Mars might be against the 1967 Outer Space Treaty. But it's something to consider.
The team's next move will be to look for water elsewhere on Mars. Although the existence of subsurface reservoirs at lower latitudes is unknown, the north pole has a sizable ice cap of its own.
The existence of basal lakes beneath the north polar ice sheet "is not unreasonable," according to Caparelli.
However, the data processing of a small number of the data that were obtained in the same manner as those that enabled us to "see" the south polar subglacial lakes has just begun.
Therefore, when the team has finished analysing the results, we will be excited to examine them. Pettinelli, meantime, would like the opportunity to send out landers to carry out seismic monitoring in order to explore the reservoirs' depths.
"It would be ideal to employ active seismic prospecting methods, which have been used in Antarctica, to find the bottom of the lakes. These methods are often used on Earth to find oil deposits. These methods could provide information about the water depth and the water body's geometry "to ScienceAlert, she said.
We might have to wait a while for that one, though, given how difficult and expensive Mars landers are to build and how difficult it would be to set up seismic detectors.
The study was released in the journal Nature Astronomy.
Comments
Post a Comment