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Roger Weller, geology instructor

by Johnathan Cunningham
Physical Geology
Spring 2011

Also visit: Mars Landforms- great views of Mars!




What can be said about the planet Mars?  It is the 4th planet away from the sun in our solar system.  Its name comes from the Roman god of war.  Mars is home to Olympus Mons, the largest mountain in the solar system,  and it contains the Borealis basin, which covers roughly 40% of the planet.   Mars can also be seen with the naked eye in early morning sky until early nighttime during spring and in the evening sky from spring to early summer.  While we often daydream about alien life living on the planet, we forget that Mars contains numerous geological landmarks and features that make it truly unique.


This picture allows you to see how large Mars is in comparison to our own planet Earth.

Mars was first explored by a satellite named Mariner 4 in 1965.  During the latter 1960ís we sent two additional satellites to investigate Mars: Mariner 4 and Mariner 6.  With the launch of the satellites, it was determined that Marís surface was composed of basalt based upon the pictures received at the end of the mission. NASA eventually wanted to land on the surface of the planet and created the Viking I and II missions to complete that task.  NASA was finally ready to launch the Viking pair in 1975 and sent them to Mars to record data.  At the time, it was popular opinion that Mars held some form of sentient life and the public looked forward to seeing evidence ďMartiansĒ on the planet.  When the Viking spacecrafts finally landed on Mars, Viking 1 was given the left hemisphere to explore while Viking II was left with the right hand hemisphere to explore.  Neither vehicle found any life but they did discover what became the first of many surprises that lied on Marsí surface.

Viking I discovered red sand grains in its landing area while Viking 2 managed to discover a large plain filled with angular rocks and impact areas that suggested Mars was hit with multiple meteors in the past. This confirmed what was discovered when Mariner 4 took photographs of Marsí surface in 1965. The red sand grains were later determined to be finely grained iron oxide dust.  Both vehicles also discovered how bright the sky looked on Marsí surface. This is caused by Marís atmosphere having numerous holes in it, so sunlight is more focused in certain areas.  Eventually scientists discovered that the Marsí surface resembled a desert. There werenít alien colonies or little green men but there were numerous geological discoveries.


Here, you can see the numerous craters that cover Marsí surface.

One major find was the discovery of Olympus Mons or Mount Olympus.  Olympus Mons is an extinct volcano and is the highest mountain in our solar system. The volcano is 24 km (78,000 feet)  tall and is located in the Tharsis region of Mars, which is in the northern hemisphere.  Its base is more than 500 km in diameter and has a cliff surrounding it that is 6 km (20,000 feet) high.  To place the height of Olympus Mons into perspective, it is about 3 times the height of Mount Everest which is only 8.8 km. Mars also contains other mountains such as Arsia Mons, Ascraeus Mons and Pavonis Mons in the Tharsis region. These mountains are located in several smooth plains called Utopia Planitia, Hells Planitia and Elysium Planitia. The fact that these large, ragged mountains are located in smooth plains create an interesting visual contrast and cannot be explained by scientists.


Here is a picture of Olympus Mons.

Another discovery was Valles Marineris (this is Latin for Mariner Valleys).  Valles Marineris has a staggering length of 4,000 km and is 7km deep. To place this in perspective with how large it is, Valles Marineris is equivalent to the continent Europe in size.  Since Mars is about half the size of Earth that means the valley covers 1/5th of the planetís surface.  NASA scientists have theorized that Valles Marineris was created by the swelling of the Tharsis area on Mars and the swelling caused the region to collapse.  Itís interesting to see how Mars is smaller than the Earth but t contains mountains and ridges that dwarf our own planets.



This picture shows you how large the Valles Marineris actually is.

The Viking pair was also able to analyze the contents of Marsí atmosphere during their expedition.  Once analyzed, NASA determined that Marsí atmosphere was: 0.3% water, 1.6% argon, 2.7% nitrogen, 0.15% oxygen and 95.5% carbon dioxide.  As mentioned before, Mars has a very thin atmosphere which produces a greenhouse effect, but it does not affect the temperature by too much; only 5 degrees. This is mainly due to the high levels of carbon dioxide in the atmosphere. Another interesting feature is that there are cloud formations on Mars but are composed of carbon dioxide.

Scientists originally planned on studying what Mars was actually composed of but that was not possible at the time of the Viking explorations.  Because of that, they can only speculate what is Mars is made of.  Scientists suspect that the planet has an iron core surrounded by a crust and mantle made up of silicates. Above that is suspected to be a dense layer of rock.

Mars is a truly unique planet in our solar system.  It is so similar to our planet Earth, yet it is so different at the same time.  Both planets have similar day cycles, cloud formations and are similar in size.  Mars also represents the adventure and exploration.  For centuries man has always dreamed of travelling to Mars and living on its surface.  While we now know that is not possible due to the harsh climate and lack of oxygen and low water levels, Mars is still worthy of our attention due to its numerous geological landmarks such as Valles Marineris and Olympus Mons.  Keep paying attention to the major discoveries on Mars because as long as we exist, so will our attempts to explore the planet and understand it.