We would see the sky, marked by the pinkish tone; the few clouds are cirrus clouds, high clouds of ice crystals. Not only are the clouds frozen; the average temperature on the surface is 55 degrees below zero, although it fluctuates enormously: between 27 and -180º C. A variation that is reminiscent, although much more pronounced, of the deserts on Earth. But the most fascinating thing is the thermal variation between the feet and the head: the ground is 20 degrees warmer than the air (it is so tenuous that it cannot retain heat), so if our feet are at a pleasant 20º, the nose will be at zero degrees! What’s more, seeing the sunrise also has its risks: in just one minute the temperature can change more than 20 degrees.
Of course, we must do the walk with a diving suit: the Martian atmosphere is composed mainly of carbon dioxide (95.32%) and with a small amount of other gases, such as nitrogen (2.7%) and argon (1.6%). ). Its free oxygen content is negligible (0.13%) and the water vapor is one thousandth that of the Earth’s atmosphere; very little, but enough to form clouds in the atmosphere and around the calderas of volcanoes, now extinct. Carbon dioxide, meanwhile, freezes to form a huge polar cap and the polar hood , a mist that levitates above the cap in winter. When spring arrives it melts and then another appears in the opposite hemisphere. Beneath this seasonal envelope is a permanent one, which is maintained even during the summer and, at least at the North Pole, is made of ice. Without oxygen, there is no ozone sphere, and the planet’s surface is swept by ultraviolet rays, which is a serious impediment to any hypothetical Martian life.
Volcanism has been a fundamental geological process on the planet . Proof of this is that there we discovered the highest volcanoes in the Solar System: the largest is Mount Olympus, 27 kilometers high and whose caldera is about 25 kilometers wide with walls two and a half kilometers deep. Looking at the sky from up there would show us a unique spectacle: it is so high that the stars can be seen in broad daylight.
Martian geology is one of the most spectacular in the Solar System. One peculiarity is that the planet is split in two : the northern lands are lower than the southern ones. The escarpment that separates them, the dichotomy or limit 1/3-2/3, is up to 5 kilometers high. It is one of the biggest mysteries on the red planet and is thought by many to represent the coastline of an ancient ocean.
The southern hemisphere is littered with ancient impact craters and that is where the Martian valley networks are found. The northern hemisphere has very few craters; it is a great empty space, Vastitas Borealis, the Northern Desert, the flattest surface of the Solar System. Some think that it was formed by the impact of an asteroid of almost 400 km (Ceres, the largest in the Solar System, measures 300 km).
Ecuador is dominated by the Tharsis dome, a dome (a steeply sloping structure formed by lava flows) as big as Asia whose center rises 10 kilometers and on which gigantic volcanoes sit. Almost all faults on Mars are radial or concentric to Tharsis. In one of them a gorge of planetary proportions was formed: Valles Marineris, the great scar of Mars. It is the Martian Grand Canyon, 2,900 km long, between 100 and 600 km wide and up to 10 km deep.
If we look at the poles we find that the north is larger than the south: it is 1,000 km long and is made up of frozen water and dry ice, CO2 ice. The concentric dark bands it has are snow-free canyons whose origin is unknown. One of these bands, Chasma Boreale, the North Canyon, nearly splits the cap in two. The existence of huge moraines in the equator (200,000 km2, almost half of Spain) suggests that the poles were there 4 or 5 million years ago and that the planet’s axis of rotation has overturned ; something that cannot happen to Earth because its axis of rotation is stabilized by our huge satellite.
Ancient Mars was a very different place than today, dry and arid . There is no doubt that water ran across the surface of Mars. A flow of one billion cubic meters per second circulated through the Ares Vallis. 300,000 circulate through the Amazon, and the great waterfall that filled the Mediterranean through Gibraltar carried only 60 million. Was there ever an ocean? It is not very clear, although its existence would explain a series of characteristics, such as the different ages of the channels or the relief similar to that of a coastal area.
