Geology Home Page physical geology historical geology planetary gems
Roger Weller, geology instructor
by Johnathan Cunningham
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.
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
Here, you can see the numerous craters that cover
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.