Cochise College Student Papers in Geology
Geology Home Page physical
geology historical
geology planetary
gems
Roger Weller,
geology instructor
wellerr@cochise.edu
Mars
Marie Reid
Physical Geology
Spring 2005
Mars: The Red Planet
The
planet Mars is also known as the Red Planet or Red World. Its surface is covered with an iron rich clay
giving the planet that reddish color.
Mars is the only planet whose surface can be seen in detail from the
Earth. Even with the unaided eye, Mars
appears redder than that of the other planets and stars in the night sky. No telescope is needed to see Mars because it
is most visible in the early morning sky from fall to early spring and in the
evening sky from the spring to early summer.
You will notice the planet because it will be a small rust-colored light
in the sky.
Since
Mars is a reddish-color, it was named after the god of war of the ancient
Romans. The Roman god of Mars was a god
of agriculture before becoming associated with the Greek Ares; those in favor
of colonizing. Though the Roman god of war
and agriculture don’t seem to go together, they really do. Mars protected those who fought for their
communities and stayed home to raise crops for food. Most people don’t associate the fact that the
month of March derives from Mars.
Mars
was explored by flybys by Mariner 4, 6 and 7 in the 1960’s. We also had Mariner 9 orbiting Mars in 1971
before NASA mounted the ambitious Viking I and II missions, which launched two
orbiters and two landers to the planet in 1975.
Both Viking landers landed on the smooth northern hemisphere. The Viking I landing site is given on the
left hemisphere and the Viking II landing site is on the right hemisphere. Viking I landed on the edge of the highland,
while Viking II landed in the middle of the lowland. Both Viking I and II carried a
mass-spectrometer for chemical analysis of the atmosphere, the soil, and there
was a camera with many other scientific instruments on each lander. The landers found no chemical evidence of
life. On the Viking I landing site, fine
grain sands were clearly visible, there were an abundant angular rocks, and the
gravel surface was probably formed by deflation. The Aeolian processes obviously were
operating in this area. The Viking II
landing site was a little bit different.
It revealed a vast plain littered with angular blocks and low drifts of
sand. These blocks might be ejected from
nearby impact craters, or they might be the weathered remnants of a lava or
debris flow. Like those at the Viking I
site, many of the rocks were pitted, as a result of wind erosion. Another remarkable feature on both views was
the bright sky in the background; this is very different from the surface
pictures taken on the Moon, where the background sky is black. The bright sky was a result of the atmosphere
that scattered sunlight within itself.
The first
spacecraft to visit Mars was Mariner 4 in 1965.
Several others followed including Mars 2, the first spacecraft to land
on Mars and the two Viking landers in 1976.
Ending a long 20 year hiatus, Mars Pathfinder landed successfully on
Mars on 4 July 1997, delivering a mobile robot rover which explored the
immediate vicinity. In early 2004, the
Spirit and
Mars is the
seventh largest planet in the Solar System and the fourth planet from the Sun. It
is located between Earth and Jupiter and is the last of the inner, terrestrial
planets. Mars has two satellites or
moons, Phobos and Deimos. These are
considered the two smallest moons in the solar system. Phobos is approximately 18 miles in diameter,
while Deimos is approximately 9 miles in diameter. They are actually two asteroids, which are
small, rocky bodies which were scattered throughout our solar system. They became moons when they became close
enough to Mars that they were “captured” by Mars’ gravity and they have been
circling ever since.
Mars rotation
period is about 24 hours and 37 minutes.
Because its spinning axis is tilted with respect to the ecliptic plane
by 24.5 degrees similar to the Earth’s, the surface of Mars should experience
seasonally variations just like the Earth.
The orbit or path which Mars takes around the Sun is called a mild
ellipse or stretched circle. The orbital
path from which Mars has to take around the Sun is about 227,940,000 km from
the Sun. A Martian year compared to
Earth is about one Earth year and ten and a half months. Mars’ diameter is approximately 6796 Kms
(4223 miles), a little more than half the size of Earth. If Earth was a baseball, Mars would be a golf
ball. Though Mars is smaller than Earth,
its surface area is about the same as the land surface area of Earth. Mars’ mass is huge at 6.4219e23 kg. It is about 128 million miles from the Sun at
its closest and 154 million miles at its farthest. The temperature of Mars seems to differ so much,
I don’t think that people may never be able to survive on this harsh
planet. The temperature ranges around
-140 to 20 degrees Celsius (-220 to -60 degrees Fahrenheit) during the winter. During the summer, it is 27 degrees Celsius
(80 degrees Fahrenheit on the day side).
People talked
about how much they would weigh on the Moon and realized there was hardly any
gravity on the Moon. If you weighed 70
lbs on Earth, you would weigh about 27 lbs on Mars. Its surface gravity is only about 38% of the
surface gravity of Earth. I am
assuming most women would love to live
on Mars with those kinds of numbers.
Mars’ atmosphere
is made up mostly of carbon dioxide. The
breakdown of the atmosphere is as follows:
·
Carbon dioxide ►95.3%
·
Nitrogen ►2.7%
·
Argon ►1.6%
·
Traces of Oxygen ►.15%
·
Water ►.03%
·
The average
pressure on the surface is only about 7 millibars (less than 1% of Earth’s),
but it varies greatly with altitude from almost 9 millibars in the deepest
basins to about 1 millibar at the top of the famous Olympus Mons mountain. Mars has a very thin layer of atmosphere, but
even though it is thin, it still has weather, including dust storms and clouds
that can cover the entire planet at one time.
Mars’ thin atmosphere produces a greenhouse effect, but it is only
enough to raise the surface temperature by 5 degrees, much less than the
Earth’s. A weak greenhouse effect is
present because of the carbon dioxide.
There are cloud formations on Mars, but on Earth, clouds represent the
condensation of water vapor in the air, on Mars, however, it could represent
the condensation of either water vapor or carbon dioxide vapor. Above the
A lot of people
ask or wonder what Mars is really made up of.
At this point, we can only speculate at some of our findings. We think
it has a core of iron, just like Earth’s. The core is dense, about 1,700 km in radius
with a molten, rocky mantle and thin crust.
Mars’ crust and mantle are composed of silicates. Mars’ relatively low density indicates that
its core probably contains a relatively large fraction of sulfur in addition to
iron (iron and iron sulfide). On top of
the iron core is a layer of rock (like Earth), but layers of rock are much
thicker than that of Earth’s.
We have seen
lots of pictures of what the surface is like on Mars, but what does it really
look like. Except for Earth, Mars has
the most highly varied and interesting terrain of any of the terrestrial
planets, though some are quite spectacular.
Much of the Martian surface is very cold and cratered, but there are also
much younger rift valleys, ridges, hills and plains. Rocky, dusty surface, complete with clouds
and dust storms (that can cover the whole planet at once) is strong enough to
support very strong winds and vast dust storms that can last for months at a time. Mars has many mountains, sandy deserts,
canyons, and many, many inactive volcanoes.
Mars has much higher mountains and far deeper canyons than the
Earth. It has the biggest stretch of
mountains, which is like going from
Close to the
equator is a vast system of interconnected canyons called Valles Marineris.
This canyon is visible from a global view of the planet, and is almost
equivalent to the width of the continental
The
The northern
hemisphere consists of plains which are much younger, lower in elevation and
have a much more complex history. Very
few shield volcanoes can be found in the southern highlands, but are more
prevalent in the northern hemisphere, in addition, some large channels appear to have been carved by rivers or huge
floods across this ancient battered surface can be recognized. There is clear evidence of erosion in many
places on Mars, including large floods and small river systems. But there was at one point in the past some sort
of fluid on the surface of Mars. These
flow channels give the Martian surface a decidedly different appearance from
that of the Moon or Mercury. Evidence
suggests Mars once had rivers, streams, lakes, and even an ocean. As the atmosphere slowly depleted into outer
space, the surface water began to permanently evaporate. Today, the only water on Mars is either
frozen in the polar caps or underground.
The age of erosion channels is estimated to be about nearly 4 billion
years old.
Because of the
lava flow and small conic structures, it is believed the plains most likely have
a volcanic origin. Dunes and wind
streaks are also found on these areas, indicative of the Aeolian process
operating in an environment covered with loose materials. These materials may be derived from the
deposits of the large flow channels emerging from the southern highlands. Mars currently lacks active plate tectonics
at the present. There is no evidence
Mars may have had tectonic activity in its early history, making comparison to
Earth all the more interesting. No
recent evidence of horizontal motion of the surface, such as the folded
mountain so common to Earth. With no
lateral plate motion, hot-spots under the crust stay in a fixed position
relative to the surface. Along with
lower surface gravity, this may account for the Tharsis Bulge and its enormous
volcanoes. There is no evidence of
current volcanic activity.
Large, but not
global, weak magnetic fields exists in various regions of Mars. Probably remnants of an earlier global filed
that has since disappeared. This may
have important implications for the structure of Mars’ interior and for the
past history of its atmosphere and hence, for the possibility of ancient life.
Mars is a desert
planet swept by frequent dust storms.
Dust storms are thought to occur every Martian year and begin in the
southern hemisphere during the summer.
During the southern spring, many small local storms could be seen in
areas where high winds develop. It is
thought a global dust storm could cut itself off when too much dust was in the
atmosphere, such that sunlight was filtered out and temperatures at the surface
would fall. The wind speed would then
drop and dust would settle out from the air.
This would usually take about three months for the atmosphere to become
clear again. The storms occur more
frequently when Mars is closest to the Sun.
Wind blows from the east in the summer hemisphere and from the west in
the winter hemisphere.
Mars has
permanent ice caps at both the North and South Poles, which are made from
carbon dioxide (dry ice). The ice caps
exhibit a layered structure with alternating layers of ice with varying
concentrations of dark dust. In northern
summer, the carbon dioxide completely sublimes, leaving a residual layer of
water ice, but it’s not known if a similar layer of water ice exists below the
southern cap since its carbon dioxide layer never completely disappears. The mechanism responsible for the layering is
unknown, but may be due to climatic changes related to long-term changes in the
inclination of Mars’ equator to the plane of its orbit. There may be water hidden below the surface
of the lower latitudes. Seasonal changes
in the extent of solar caps changes the global atmospheric pressure by about
25%. The south polar cap is permanent
and is composed predominantly of solid carbon dioxide with some water. It expands and contracts with the seasons as
the dry ice vaporizes and sublimes. The
north cap is seasonal, so all the carbon dioxide is vaporized in the summer,
leaving a residual cap of water ice only.
From telescopic observations, the polar ice caps of Mars can be
identified, they are that predominant.
On both poles, there may be permanent water ice sheet spread over the
surface, more often, carbon dioxide ice are detected in the
I found some
pictures of Mars that really show all the different land marks that makes this
planet so different from ours, but so alike.
Fig. 1. This a global picture of Mars
as a satellite passed by.
Fig. 2. This is the Martian atmosphere
and you can really see the red from the iron content of the planet.
Fig. 3. Pictures captured from Viking
I.
Fig. 4. Pictures captured from Viking
II.
Fig. 5. Here, again is one of the many
craters that cover the planet Mars.
Fig. 6. This a picture of Crater Yuty.
Fig. 7. It is so amazing to see all the
craters that are on Mars. Some are
gigantic, while others are much smaller.
Fig. 8. With this crater, you can see
the outer layers from the impact of the asteroid when it hit Mars.
Fig. 9. This is a multiple ring crater.
Fig. 10. The above picture is one of
the many distinct channels on Mars
Fig. 11. Here is another picture of the
huge channels that cover the planet Mars.
Fig. 12. This photo shows all the
drainage systems thought to have had carried water at one time.
Fig. 13. This is also a global picture
of Mars, but it shows the Valles Marineris.
This valley is over 2,000 miles long, deep enough to hold a mountain
range.
Fig. 14. This is a sketch of the land
mass of Mars.
Fig. 15. Here are clouds over the southern
region of the poles.
Fig. 16. This is a picture of the
Northern Ice Cap.
Fig. 17. This is unusual picture of the
Northern Ice Caps.
Fig. 18. This is a storm of the South
Pole Region
Fig. 19. This is an active cyclone on
Mars.
Fig. 20. These are organisms were found
on a meteorite from Mars, giving humans hopes of life on Mars.
Fig. 21. Of course, here is the famous
picture of the “face” of Mars.
Works
Cited
Mars. 17 March 2005. http://www.indianchild.com/mars.htm
Mars. Bill Arnett. 28 December 2000. 17
March 2005.
http://hercules.geology.uiuc.edu/~hsui/classes/geo116/lectures/mars.html
Mars Express Makes First Photo of Red
Planet. Imaginova corp. Space.com Staff. 3 December
2003.
17 March 2005. http: www.space.com/scienceastronmy/express_photo_031203
.html
Planet Mars. Hsui. 17 March 2005. http://hercules.geology.uicu.edu/~hsui/classes
geo116/lectures/mars.html
Solar System: Inner Planets – Mars. CyberScientist@onr.navy.mil. 17
March 2005.
http://www.onr.navy.mil/focus/spacesciences.solarsystem/mars1.htm
Mars – from Eric Weisstein’s World of
Astronomy. Eric W. Weisstein. 17 March 2005.
http://scienceworld.wolfram.com/astronomy/Mars.html
The Planet Mars – KidAstronomy.Com.
KidsAstronomy.com. 17 March 2005.
http://www.kidsastronomy.com/mars.htm
The Planet Mars – The Red Planet. Vic
Stathopoulos. 8 August 2004. 17 March 2005.
http://members.lycos.co.uk/spaceprojects/planetmars.html?