Planet Mars, from pole to pole

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A new image of Mars Express Orbiter from ESA shows exactly the difference of the regions of Mars. From the northern polar region to Helles Planitia, in the south, Mars is a puzzle of different types of terrain. At the heart of all this is what is called the Martian dichotomy.

Mars from one pole to another, imagined by the Mars Express orbiter. Image Credit: ESA / DLR / FU Berlin, CC BY-SA 3.0 IGO

The region of the north pole of Mars is obscured by clouds, tendrils extending southward into the northern hemisphere. Clouds block the view of the polar region, but we know that it is still covered with ice, thicker in winter and thinner in summer. We also know that it is sunk in altitude. The northern hemisphere is 2 km lower than the southern hemisphere. In ancient Martian times, the northern hemisphere could be covered with water.

The northern hemisphere is characterized by low plains without many impact basins. This suggests to scientists that he is much younger. It certainly looks younger next to the southern hemisphere, heavily marked by craters of all sizes.

The geography of the plain that dominates the northern hemisphere is called Vastitas Borealis and extends all around the planet. The topographic map of Mars develops it.

<img src = "https://www.universetoday.com/wp-content/uploads/2019/09/1280px-Mars_topography_MOLA_dataset_with_poles_HiRes-1024×462.jpg" alt = " A Mercatorian topographic map of Mars from MOLA data (Mars Orbiter laser altimeter). Blue is at low altitude, red at high altitude. The northern hemisphere of Mars is about 2 km lower than the southern hemisphere. Image Credit: By NASA / JPL / USGS – http://mola.gsfc.nasa.gov/images.html and http://photojournal.jpl.nasa.gov/catalog/PIA02993, public domain, https : // commons .wikimedia.org / w / index.php? curid = 32873138 "class =" wp-image-143499 "srcset =" https://www.universetoday.com/wp-content/uploads/2019/09/1280px-Mars_topography_MOLA_downloadset_with_poles_Hi -1024×462.jpg 1024w, https: // www .universetoday.com / wp-content / uploads / 2019/09 / 1280px-Mars_topography_MOLA_dataset_with_poles_HiRes-250×113.jpg 250w, https://www.universetoday.com/wp- The following position .com / wp-content / uploads / 2019 / 09 / 1280px-Mars_topography_MOLA_dataset_with_poles_HiRes.jpg 1280w "sizes =" (maximum width: 767px) 89vw, (maximum width: 1000px) 54vw, 54vw, (maximum width: 107vp, 541px) 580px "/>
A Mercatorian topographic map of Mars from MOLA data (Mars Orbiter laser altimeter). Blue is at low altitude, red at high altitude. The northern hemisphere of Mars is about 2 km lower than the southern hemisphere. Image Credit: By NASA / JPL / USGS – http://mola.gsfc.nasa.gov/images.html and http://photojournal.jpl.nasa.gov/catalog/PIA02993, public domain, https : // commons .wikimedia.org / w / index.php? curid = 32873138

A rugged terrain separates the northern hemisphere of Mars from its southern hemisphere. The band includes mesas, cliffs, fractures, canyons and flat-topped valleys. Scientists believe that many of these features have been sculpted by water and ice, while some have probably been sculpted by lava flows from massive Mars volcanoes.

A representative area of ​​this strip of land is called Cydonia Mensae, a highly studied area. It contains the famous "Face on Mars" that roughly looks like a human face.

Part of the Cydonia Mensae region on Mars, in the transition region between the heavily cratered Southern Uplands and the Smooth Northern Lowlands. This image comes from the high resolution stereo camera of the Mars Express orbiter from ESA. Image Credit: ESA / DLR / FU Berlin, CC BY-SA 3.0 IGO
Part of the Cydonia Mensae region on Mars, in the transition region between the heavily cratered Southern Uplands and the Smooth Northern Lowlands. This image comes from the high resolution stereo camera of the Mars Express orbiter from ESA. Image Credit: ESA / DLR / FU Berlin, CC BY-SA 3.0 IGO

The northern plains, just below the polar cap, are dark gray and dusty. With a prominent escarpment, they create a dark band on the surface of the planet, mostly beige. Traveling to the south, then come the vast orange highlands, marked on all sides with craters. Scientists believe that the southern highlands are old and that some of these craters date back to the ancient history of the planet.

The parts of the southern mountains visible on the main image are Arabia Terra (top left) and Terra Sabaea (center and bottom right), while at the foot, almost as far as the eye can see, is the l & # 39; Huge Planitia Hellas, vast plain inside Hellas impact basin.

A topographic slice of Mars with labels. Image Credit: NASA / MGS / MOLA Science Team, FU Berlin
A topographic slice of Mars with labels. Image Credit: NASA / MGS / MOLA Science Team, FU Berlin

The Martian dichotomy, the division between the northern terrain and the southern terrain is one of the greatest mysteries of Mars. Why are the two regions so different? What is the cause of the discrepancy?

Mars could have had tectonic plates similar to those of the Earth in its past. Some geological processes in the mantle of the planet may be responsible. This may have been caused by an incredibly huge impact in the past. Maybe a combination of factors.

The unique impact hypothesis has gained ground in recent years as we observe Mars better and better. One of the drawbacks is that an impact of the necessary magnitude would have masked large parts of Mars in the ejecta. But there is no evidence of this on the surface. On the other hand, if it happened long enough, perhaps 4.5 billion years ago, erosion could have suppressed evidence of this coverage.

The Martian dichotomy could have been created by a kind of plate tectonics that moved huge amounts of material around the planet. Since our understanding of this process on Earth is still very limited, it is difficult to surmise the same processes on Mars. But it is possible that cells or plumes of material from the mantle of the planet have risen to the surface in one hemisphere, while the materials have collapsed in the other. But as there is no evidence of plate tectonics on Mars, it is unlikely.

This image shows a slice of the red planet from the north polar cap down and highlights crater bands and pocket marks from the Terra Sabaea and Terra Terra regions. Image Credit: NASA / Viking, FU Berlin
This image shows a slice of the red planet from the north polar cap down and highlights crater bands and pocket marks from the Terra Sabaea and Terra Terra regions. Image Credit: NASA / Viking, FU Berlin

There is even a hypothesis that several important impacts have created the dichotomy. But the problem with all these proposed explanations for the dichotomy is that we simply do not have enough evidence. Not to confirm one, nor to really exclude. Maybe NASA's InSight Lander will bring some light.

There are currently six orbiters on Mars and on the surface, the Curiosity rover and the InSight lander. And several other missions are planned.

Over time, our scientific knowledge of Mars will continue to grow and eventually, in the very distant future, we will solve the Martian dichotomy.

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