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First lake of liquid water discovered on Mars? The glossy horizontal feature in this image represents the icy surface of Mars. The polar-polar stratified deposits – layers of ice and dust – are seen at a depth of about one mile (1.5 km). Here is a base layer that in some areas is even brighter than surface reflections, highlighted in blue. The analysis of the reflected signals suggests liquid water. Image via ESA / NASA / JPL / ASI / Univ. Rome; R. Orosei et al. 2018.
Water on Mars! Again! Does not it seem every year or two, we hear about some new discovery related to water on the red planet? Until now, discoveries have more specifically focused on ice, possible small amounts of aqueous brine that temporarily flow to the surface or even more evidence of large amounts of water on ancient Mars. But on July 25, 2018, the European Space Agency (ESA) announced something new: the first evidence of a liquid water lake under a thick layer of ice at the South Pole of the planet . It can work from a real lake or a layer of liquid water, though cold and salty.
It has long been assumed that there could be pockets of liquid water deep beneath the surface, where the temperatures would be a little warmer and the water probably salty enough to remain liquid. It is also well known that the melting point of water decreases under the pressure of an overlying glacier. Similar lakes have been found under thick ice at the Earth's poles, such as Lake Vostok in Antarctica.
Now it seems that ESA's Mars Express ship has finally found an underwater lake on the neighboring planet. The large pond or lake is under several layers of ice and dust near the south pole of Mars. The orbiter was using a ground penetrating radar, Mars' advanced radar for the underground and ionospheric (MARSIS) sounding instrument – long used to find buried ice deposits – to detect the suspected lake. . The ice deposits in the 124-mile wide (200 km wide) area studied extend about one mile (about 1.5 km).
Below that, scientists found a brilliant radar reflection in an area 12 miles wide (20 km wide). The nature of the bright area corresponded to what scientists expect from liquid water.
The study area is indicated on the left-hand image. The radar "fingerprints" on the surface, in several orbits of the Mars Express spacecraft, are shown in the right image. The fingerprints are color-coded corresponding to the "power" of the radar signal reflected by the characteristics below the surface. The large blue zone near the center corresponds to the main radar-illuminated area, detected on many of the overlapping orbits of the spacecraft. Context Map: NASA / Viking; History of THEMIS: NASA / JPL-Caltech / Arizona State University
From the new document:
The presence of liquid water at the base of the Martian polar ice caps has long been suspected but not observed . We studied the Planum Austral region using the MARSIS instrument, a low frequency radar on the Mars Express spacecraft. Radar profiles collected between May 2012 and December 2015 contain evidence of liquid water trapped beneath the ice of polar-stratified deposits. Abnormally bright subterranean reflections are evident in a well-defined area 20 kilometers wide centered at 193 ° E, 81 ° S, which is surrounded by much less reflective zones. The quantitative analysis of radar signals shows that this luminous characteristic has a high relative dielectric permittivity (> 15), corresponding to that of aquiferous materials.
We interpret this characteristic as a stable body of liquid water on Mars.
According to Roberto Orosei, principal investigator of the MARSIS experiment and lead author of the new article published in the journal Science :
This submarine anomaly on Mars has radar properties corresponding to water or sediments rich in water. This is just a small area of study; It's an exciting prospect to think that there might be more of these underground pockets of water elsewhere, to discover.
The southern polar cap, seen by Mars Global Surveyor (MGS) on April 17, 2000. Image via NASA / JPL / MSSS
Scientists involved in the research believe that the bright zone is an interface between the above-mentioned ice root and a stable body of liquid salt water. To be detected by MARSIS, the liquid deposit must have a thickness of at least 10 cm. As Andrea Cicchetti, director of operations MARSIS and a co-author on the new paper, added:
We had seen interesting sub-surface indices for years but we could not reproduce the result of the new one. orbit in orbit and the resolution of our data was previously too low. We had to develop a new mode of operation to bypass the embedded processing and trigger a higher sampling rate, thus improving the resolution of the fingerprint of our dataset: we are now seeing things that were simply not possible.
a reason for caution, as the results have not yet been confirmed by another orbiter, but the Mars Express data is certainly convincing. Some researchers also suggest that the lake could be a region of very wet soil or "muddy sediments" instead of actual liquid water, but only further study will determine what is the case. Mars Reconnaissance Orbiter (MRO) NASA also looked at the same area with its radar, called SHARAD, but did not detect the lake. However, it is thought that this is probably due to the fact that its radar is tuned to different wavelengths compared to that of Mars Express, which are dispersed by the polar ice before they reach it. the depth of the lake
. ] appears that the first underground Martian lake has been found. It is also likely that if this lake exists, there are probably others too. As noted Elena Pettinelli of Roma Tre University of Italy, and coauthor of the document:
There are other areas that seem similar. There is no reason to say that it is the only one.
The alleged submarine lake on Mars is thought to resemble Vostok Lake in Antarctica. Image by National Science Foundation.
Of course, the big question that comes to mind is, what about life? Bacteria have been found to exist very well in the subglacial lakes of the Earth, making the possibility all the more exciting. Dmitry Titov, scientist of ESA's Mars Express project, said:
This exciting discovery is a culmination of global science and will contribute to our understanding of the evolution of Mars, the planet, and the planet. water history on our neighboring planet and its habitability. The long duration of Mars Express and the exhausting effort of the radar team to overcome many analytical challenges have allowed to achieve this long-awaited result, demonstrating that the mission and its payload still have a great scientific potential.
The ESA Artist Concept The Mars Express Spacecraft Orbiting Mars, via NASA Eyes on the Solar System / Bob Trembley / The Catholic Astronomer
Conclusion: The water was again discovered on Mars. But this time, it seems to be different, like in a real underground lake – something theorized to exist but never seen until now. If confirmed, it would be the first body of liquid water ever found on the otherwise dry red planet.
Source: Radar evidence of subglacial liquid water on Mars
Via ESA
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