Planetologists have found large deposits of ice in the northern hemisphere of Mars and traces of streams of melt water moving along its surface relatively recently, during the heyday of dinosaurs on Earth, according to an article published in the journal JGR: Planets.
“We have long thought that the mid-latitudes of Mars are too cold for streams of melt water to form there - the average temperatures there do not exceed 55 degrees Celsius below zero. Our observations show that underground volcanic activity and glacier collisions may have generated enough heat in the recent past to melt some of them,”says Frances Butcher of the UK Open University in Milton Keynes.
In recent years, scientists have found many hints that rivers, lakes and entire oceans of water existed on the surface of Mars in ancient times, containing almost as much liquid as our Arctic Ocean. On the other hand, some planetary scientists believe that even in ancient times, Mars could be too cold for the permanent existence of the oceans, and its water could be in a liquid state only after volcanic eruptions.
The discovery of traces of the most powerful oceanic tsunamis on Mars, as well as some other data on its geology, make many scientists believe that liquid water could not always exist on Mars, but only occasionally, when large meteorites fell on Mars or when its volcanoes "woke up". Streams of such melt water could break through giant channels on the surface of Mars and form temporary oceans and lakes that did not freeze for hundreds of thousands and millions of years.
Butcher and his colleagues found that similar episodes of ice melting could have occurred on Mars as recently as about 110 million years ago, studying images of temperate latitudes in the planet's northern hemisphere taken with the MRO probe cameras.
The glaciers of Earth and Mars, as scientists note, do not stand still, but constantly move down the slopes of mountains or plains, retreating and advancing as temperatures rise or fall. These ice movements do not pass without leaving a trace on the surface of the planets - very specific landforms appear on it, such as fjords, moraine ridges, sheep's foreheads, drumlins and other objects, which unequivocally indicate that a glacier once existed here.
By analyzing images from the MRO, Butcher's team tried to find similar landforms located near modern Martian glaciers. Their proximity, scientists hoped, would help them understand how fast the ice of Mars is moving today and whether there have been large-scale retreats and advances of ice caps in the recent and distant past.
On the Tempe plain, located to the north of the volcanic plateau Tarsis, the NASA probe managed to find the so-called ozois - rather low and very long hills, similar in shape to railroad shafts.
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Ozes, unlike many other glacial landforms, are formed not as a result of the movement of the ice itself, but of melt water flows that arise at the border between the foot of the glacier and the ground and lay narrow but long channels several tens of kilometers long in it.
The part of the Tempe Plain, on which the ozes and the associated glacier are located, was formed about 150-110 million years ago. This means that streams of "real" water flowed along the surface of the red planet in the very recent past, when Mars had already cooled down and lost almost all of its atmosphere.
What could melt these ice and make them retreat? Scientists believe that the source of heat in this case was subglacial volcanoes - a geological fault passes under the Tempe plain, which could have produced a large amount of heat and energy in the past.
These holes and the neighboring glaciers, according to Butcher and his colleagues, can become one of the most interesting places for the construction of future bases and colonies for several reasons at once. Here, not only large reserves of water have been preserved, but the glacier itself may hide potential traces of Martian life that existed on the surface of the planet in the distant past.