The massive equatorial ice deposits of Medusae Crater on Mars

Mars has large underground ice deposits in the polar regions, but also near the equator. If this phrase surprised you, you shouldn't, because it has been known for more than a decade. But we now know that some of these deposits are much larger, as they can be up to 3.7 kilometers thick. Let us remember that news about Martian ice has been repeated since the 1970s, when images taken from the Mariner 9 and Viking 1 and 2 probes showed the presence of permafrost in large areas of the planet due to the shape of the material found around some craters. . But the extent of this ice was not known until in 2001, NASA's Mars Odyssey rover – which is still incredibly functional – confirmed the existence of underground ice deposits using its neutron spectrometer. Although Mars Odyssey verified the presence of ice in the polar regions, deposits near the equator were a surprise.

However, the Mars Odyssey data have been difficult to interpret, and the exact amount of ice has remained a matter of debate. Probes had to be sent out equipped with radar that would allow them to reach into the Earth's interior in search of ice. In 2003 and 2005, ESA's Mars Express lander and NASA's MRO lander were launched, respectively (and both are still incredibly functional). Mars Express contains the MARSIS radar (Advanced Mars radar for subsurface and ionosphere sounding(and MRO Sharad Radar)Shallow radarBoth of them studied the interior of Mars and the distribution of ice globally. One of the areas studied by these radars is the Medusae Fossil Formation (MFF), a series of large, bizarre rock masses about 5,000 km long located near the equator in a transition zone between the rugged Southern Hemisphere and the southern plains. Northern hemisphere. According to the radar, the rock masses appear to have been formed from deposits of a thin, radar-transparent material up to 2.5 kilometers thick. There was a possibility that it was composed of compressed dust or ash, that is, it was equivalent to… Yardang Floor – because MFF is the main source of dust on the planet. The massifs are called Amazonis Mensa, Eumenides Dorsum, Lucus Planum, Aeolis Planum, Zephyria Planum, and Gordii Dorsum, and their estimated volume ranges between 1.4 and 1.9 million cubic kilometers.

Using additional data from the MARSIS radar and knowledge from more than a decade of studying Mars using radar, new research concludes that the deposits contain a high percentage of ice and are thicker than expected, up to 3.7 kilometers thick, a depth similar to the depth of the polar cap. From the southern hemisphere. Its radar appearance is similar to that of the Martian polar caps, in which layers of regolith with varying proportions of water ice alternate with drier layers (and some carbon dioxide ice deposits). MARSIS has already shown that tropical MFF deposits have the same dielectric properties as polar deposits, but now it is also possible to resolve a layered structure similar to that found at the poles. The equatorial deposits of the MFF are massive, and depending on the percentage of ice in them, once melted they could cover the entirety of Mars – and I repeat the entire planet – in a layer of water 1.5 to 2.7 meters deep (assuming the planet was perfectly spherical). . Or, alternatively, water from these reservoirs could fill the Earth's Red Sea or the Great Lakes of North America (as an exercise I leave it to the reader to calculate how much this is in santiagobernabéus, sb, which is the SI unit of area, length and volume). From a Martian perspective, these deposits, if confirmed, would contain half the amount of water found in the planet's entire north polar cap.

For this research, data from the MARSIS radar is crucial due to its ability to penetrate depths of up to several kilometres, while SHARAD is able to better distinguish the separation between different layers, but only up to approximately 800 meters underground. Of course, unlike other areas with underground ice near the equator, these ice layers will not be easy to access for use in manned or unmanned missions, as they are covered by hundreds of meters of dust deposits that range between 300 and 600 meters thick. . The question many may ask is, how could there be huge deposits of ice on the Martian equator? Because even though the Red Planet is much colder than Earth, that ice shouldn't be there (or at least not in that amount). We do not know the exact answer, but everything indicates that the reason should be sought in periodic changes in the inclination of the axis of rotation of the planet, which caused significant climate changes not only on a time scale of millions of years, but even in very short periods of no more than thousands of years ( Mars' axis, currently with a tilt similar to Earth's, can reach a tilt of up to 60 degrees, causing glaciers and other ice deposits to form at very low latitudes).

Not surprisingly, precise study of the size, distribution and thickness of Martian icy deposits is one of the priorities of the scientific community, which is why NASA wants to send an orbiter equipped with high-resolution radar, such as the I-MIM mission (unfortunately, budget shortfalls due to the development of the MSR Sample Return mission have delayed this mission into the next decade). As we can see, the ice on Mars continues to get people talking.

References:

• https://www.esa.int/Science_Exploration/Space_Science/Buried_water_ice_at_Mars_s_equator
• https://www.si.edu/newsdesk/releases/new-study-reveals-evidence-ice-rich-layered-deposit-mars
• https://www.psi.edu/blog/vast-potential-ice-rich-deposit-found-in-martian-equatorial-region/