With massive volcanoes, deep canyons, and craters that may or may not host running water, Mars is a world with immense contrasts. When we set the first Red Planet colonies in action, it will be an awesome place for potential visitors to visit. For the protection and logistical purposes, the landing sites for these future missions would obviously need to be flat fields, but maybe some more fascinating geology might land within a few days' drive. Here are several places that may be seen by potential Martians.
The most serious volcano in the solar system is Olympus Mons. Located in the volcanic zone of Tharsis, according to NASA, it's around the same scale as the state of Arizona. Its height of 25 kilometers (16 miles) makes it about three times the height of Mount Everest on Earth, which is about 8.9 km (5.5 miles) high.
Olympus Mons is a giant volcano with shields, which was created after slowly crawling lava down its slopes. This means that, since the average slope is just 5 percent, the mountain is potentially easy for potential adventurers to ascend. A stunning depression about 53 miles (85 km) wide is at its summit, created by magma chambers that lost lava (probably after an eruption) and collapsed.
It is worth hanging around to look at any of the other volcanoes in the Tharsis area when you're hiking around Olympus Mons. According to NASA, Tharsis hosts 12 gigantic volcanoes in a range approximately 2500 miles (4000 km) wide. These volcanoes appear to be much bigger than those on Earth, like Olympus Mons, possibly because Mars has a weaker gravitational force that encourages the volcanoes to rise higher. For as much as two billion years, or half of Mars' history, these volcanoes could have erupted.
The illustration here shows the area of eastern Tharsis, as pictured by Viking 1 in 1980. You can see three shield volcanoes on the left, from top to bottom, about 16 miles (25 km) high: Ascraeus Mons, Pavonis Mons, and Arsia Mons. There's another shield volcano on the upper right, named Tharsis Tholus.
Not only is Mars home to the solar system's largest volcano, but also the largest canyon. According to NASA, Valles Marineris is approximately 1850 miles (3000 km) long. It's almost four times longer than the Grand Canyon, which is about 500 miles deep (800 km).
How Valles Marineris came to be, researchers are not sure, but there are many hypotheses about its shape. Many scientists say that it contributed to the growth of Valles Marineris when the Tharsis area was formed. The crust was forced upward by lava flowing through the volcanic zone, which broke the crust into cracks in other areas. These fractures have developed into Valles Marineris over time.
The North and South Poles
At its poles, Mars has two icy zones, with significantly different compositions; the north pole (pictured) was closely observed in 2008 by the Phoenix lander, while our observations of the south pole come from orbiters. According to NASA, temperatures at both the north and south poles are so frigid during the winter that carbon dioxide condenses on the soil into ice from the atmosphere.
In summer, as carbon dioxide sublimates back into the atmosphere, the process reverses. In the northern hemisphere, carbon dioxide finally disappears and leaves behind a water ice sheet. Yet in the southern atmosphere, some of the carbon dioxide ice persists. Much of this ice migration has tremendous implications on the Martian climate, producing winds and other effects.
Gale Crater and Mount Sharp (Aeolis Mons)
Gale Crater, made famous by the landing of the Curiosity rover in 2012, is host to extensive past waterproof. Within weeks of landing, Curiosity came across a stream bed and uncovered more substantial signs of water on its path around the crater floor. A local volcano named Mount Sharp (Aeolis Mons) is now summiting Fascination and gazing at the geological characteristics in each of its strata.
One of the more surprising discoveries of Curiosity was the detection, on many occasions, of complex organic molecules in the field. Data from 2018 showed that these organics were found within 3.5 billion-year-old rocks. Simultaneously with the organic findings, researchers announced that the rover had discovered variations in methane concentrations in the atmosphere over the seasons. Methane is an ingredient that both bacteria and natural phenomena will produce, but if that's a sign of life, it's unknown.
Medusae Fossae is one of Mars' weirdest sites, with some people also speculating that it provides signs of a UFO accident of some kind. The more plausible theory is that it is an immense geological deposit, around one-fifth the size of the United States. Over time, winds sculpted some stunning formations into the rocks. But researchers would need further studies to understand how Medusae Fossae are produced by these volcanoes. A 2018 study indicated that the formation could have resulted from hundreds of times over 500 million years of immensely huge volcanic eruptions. These eruptions must have warmed the world of the Red Planet as greenhouse gases drifted into the atmosphere from the volcanoes.
Recurring Slope Lineae in Hale Crater
Mars is home to unusual features called recurrent slope lineae, which during warm weather appear to form on the sides of steep craters. It's hard, however, to work out what these RSLs are. Pictures seen here from the Hale Crater (as well as other locations) indicate areas where hydration signals were obtained by spectroscopy. NASA originally announced in 2015 that the hydrated salts could be indicators of flowing water on the surface, but subsequent reports said the RSL may be formed by atmospheric water or dry sand flows. In fact, to see what their true existence is, we will have to get close to these RSLs. Yet there is a challenge here.
'Ghost Dunes' in Noctis Labyrinthus and Hellas basin
These days, Mars is a world mainly shaped by wind, as the water evaporated as its atmosphere thinned out. But we can see abundant signs of past water, such as "ghost dunes" regions located in the basin of Noctis Labyrinthus and Hellas. These regions used to contain dunes that were tens of meters tall, researchers claim. Later, lava or water-filled the dunes, which retained their roots as the tops washed down.
Old dunes like these demonstrate how winds used to flow on ancient Mars, which in turn provides some information to climatologists as to the Red Planet's ancient climate. There could be bacteria hidden in these dunes' sheltered areas in a far more exciting twist, safe from the radiation and wind that would otherwise blow them free.