2 h hours ago|Source: ESA
Wind-blown piles of dust or layers of ice? ESA’s Mars Express probe has re-examined one of Mars’ most mysterious features to shed light on its composition. The results suggest that layers of water ice extend beneath the surface of the Red Planet. This is the largest amount of water ever found in this part of the planet.
When the Mars Express probe explored the Medusae Fossae Formation (MFF) more than fifteen years ago, it revealed massive deposits up to 2.5 kilometers deep. However, it was not clear from these first observations what these deposits are made of. For a long time, scientists could only wildly speculate what it could be. Only new research has now brought the answer. The answer did not disappoint the scientists.
“We re-examined the MFF using more recent data from the Mars Express probe’s MARSIS radar and found that the deposits are even thicker than we thought: up to 3.7 kilometers across,” said Thomas Watters of the Smithsonian Institution, who led both the original research, so does the new one. “It’s amazing that these radar signals match what we would expect from layered ice and are similar to the signals we know from the polar caps of Mars. And we know about them that they are very rich in ice.’
There is a huge amount of this ice. If it melted completely, it would cover the entire planet with a sea – a layer of water 1.5 to 2.7 meters deep. It is the largest amount of water ever found in this part of Mars. And one more comparison: it is about so much that it would completely fill the Red Sea on Earth.
Martian Lasagna
The MFF formation consists of several formations with a diameter of hundreds of kilometers and a depth of several kilometers. Located on the boundary between the Martian Highlands and the Martian Plains, these formations are likely the largest source of dust on Mars and one of the most extensive deposits on the planet.
Initial observations from the Mars Express probe showed that the MFF is relatively transparent to radars and has a low density, properties expected of glacial deposits. But scientists could not rule out even a less optimistic possibility: that these formations are actually giant lakes of wind-blown dust, volcanic ash, or sediments. That would be much less interesting for learning about Mars’ past – of course, mere dust is nowhere near as important for learning about the past as frozen water.
“And that’s where the new radar data comes in! Given how deep the MFF is, if it were just a giant pile of dust, we would expect it to compact under its own weight,” explained study co-author Andrea Cicchetti from the National Institute for Astrophysics in Italy. “But that would create something much denser than what we actually see with MARSIS. When we modeled how different materials would behave without ice, none of it could explain the properties of MFF – in short, we need ice to explain it.”
The new results suggest that the MFF is actually made up of layers of dust and ice – much like a giant lasagna. All of this is covered by a layer of dry dust or ash several hundred meters thick – like cheese covering a lasagna. It protects the formation from influences from the external environment.
Wet, not dry planet
Although Mars currently appears to be a dry world, its surface is full of evidence that it was once partially covered by water. Scientists have already found dry riverbeds, prehistoric oceans, lakes and valleys washed out by water there. In addition, there are significant reserves of water ice on Mars, especially at the poles.
The vast reserves of ice near the equator, which probably lie beneath the dry surface of the MFF, could not have formed under the planet’s current climate. They must have originated in the previous climatic epoch.
“The latest analysis challenges our understanding of the formation of the Medusae Fossae. But it raises as many questions as answers,” adds Colin Wilson from ESA. “When did these ice deposits form and what did Mars look like at that time? If confirmed to be water ice, these massive deposits will change our understanding of Martian climate history. Any ancient water reservoir would be a fascinating target for human or robotic exploration.”
Record for human colonization
The extent and location of these ice deposits make them a treasure trove for humanity’s future on Mars. Missions to the Red Planet will have to land near the planet’s equator, far from the ice-rich polar caps or glaciers at high latitudes. And they will need water as a resource, so finding ice in this area is almost a must for human missions to the planet.
“Unfortunately, these deposits are covered by hundreds of meters of dust, making them inaccessible for the next few decades. But every piece of ice found will help us to get a better idea of where water on Mars flowed before and where it can be found today,” the authors of the research add.
2024-01-18 13:58:36
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