Mars - Module 9

. . . by Scott Hughes, Kari Hetcher and Mary Hodges

Reading:  Chapters 11, 12, 13 and 27 in The New Solar System, 4th edition..

This image of Mars was taken by the Hubble Space Telescope. Click the picture to see a larger version. mars Visit "The Planet Mars" for an overview of the planet Mars by the U. S. Geological Survey..

As you can see by the following chart, Mars has had many exploration projects, and many yet to come. This exploration of the planet Mars has piqued our interest in our nearest planetary neighbor. We have questions about the geologic history of Mars, as well as the possibility of life on the planet. It is easy to understand why scientists have always been interested in the "Red Planet." Mars is so close, and it is very much like Earth. Wind-blown deserts, volcanic shields, polar ice caps, and evidence of water erosion abound on this harsh, cold surface.

MISSIONS TO MARS: Visit the NASA website that covers Past, Present and Future missions to explore and map Mars.

In this module we will examine the two major regions of the planet Mars, the old, cratered highlands of the Southern Hemisphere, and the younger, flatter plains of the north. In addition, we will compare many of the surface features to those found on Earth. Hopefully, you will begin to not only see the similarities of these two planets, but will also understand the vast differences between them.lander Remember that there are a lot of web sites out there specifically devoted to Mars and the missions to Mars. Many are listed at he end of this module, so check out any of these for further information or to see some fabulous pictures of the Mars’ surface.

This is a view of the Martian landscape by the Viking 2 Lander, (image courtesy of Planetary Data System, JPL/NASA).

Cratered Highlands of the Southern Hemisphere

The Martian surface is a heavily cratered surface typical of the southern hemisphere of Mars. surfaceThe high density of craters implies that this region is very old, probably approaching 4 billion years. (Viking Orbiter mosaic MC23SW).

The southern and northern hemispheres of Mars are so different that they are divided into separate geologic provinces. The southern hemisphere has many large, multi-ring craters and basins, and volcanic intercrater terrain, very similar to Mercury and the Earth’s Moon. These craters were probably formed by intense bombardment early in the planet’s history. The craters on Mars differ from those on Mercury and the Moon, in that the ejecta of Martian craters looks much more fluid than that of the ejecta on the Moon. When  meteorites or asteroids collided with Mars, they probably interacted with the local ground water or ground ice that was trapped within the Martian surface.crater The heat and pressure of impact could have fluidized this water and formed a mud-like flow of overlapping lobes out and away from the crater. These types of craters are called rampart craters.

This photo of the crater Yuty at 22o N, 34o W shows fluidized ejecta radiatiating from the crater.  Click the photo to see a larger image.  This photo was taken by one of the Viking orbiters. (Viking Orbiter Image 3A07, courtesy JSC/NASA).

The Plains of the Northern Hemisphere

Volcanic plains, huge crustal uplifts, and volcanic shields dominate the Northern Hemisphere of Mars. Elysium and Tharsis regions represent major sites of volcanism on Mars. This is strikingly different from the southern Cratered Uplands, and the lack of dominating craters in the north probably indicates that it is much younger. No one knows exactly why these two regions differ so much or why there is such a dramatic change from one region to the other, at the global escarpment separating them, but much work has been done to characterize each region and understand them separately.

The Viking and Mariner landers, as well as the Pathfinder mission touched down in the northern plains. Most of the pictures we see are from this northern area. These plains are complex in origin. There are two major uplifted areas in the Northern Hemisphere, the Tharsis uplift and the Elysium uplift that may have been caused by thermal processes within the lithosphere.

Near the ice of the north pole on Mars, dunes give evidence of eolian transport on Mars.  We know that there is enough atmospheric circulation on Mars to create dust storms.  Eolian features of Mars will be discussed below, but for now, you may want to visit Figures from the North Polar Science paper for some information about the Mars north pole.


The Tharsis uplift (Tharsis Montes)

The Tharsis region is at the center of a huge bulge in the surface that is over 4000 km across and 10 km high. Huge shield volcanoes dominate the Tharsis region, including Olympus Mons on the northwest flank, the largest shield volcano in the solar system. Olympus Mons has a complex crater at its summit, called a caldera that formed from the collapse of the volcano peak. This and other volcanoes of the Tharsis and Elysium regions appear to have formed by a series of fluid lava flow eruptions that carpeted their flanks and slowly built up the high features we see today.

Olympus Mons is presumed to be the youngest of the volcanoes because of its height and extent, while others have been eroded considerably over their history. Most of the volcanoes of the Northern Hemisphere plains show varied levels of cratering; indicating that volcanism has played a part in the shaping of the Martian landscape throughout much of its history. Visit Vic Camp's website (UCSD) on How Volcanoes Work -- Mars!

Click each of the following pictures for more information about each. (Images courtesy of NASA).

tharsis region olympus mons

This 3-dimensional image below was created from several images of Olympus Mons. Each image was taken from a different spacecraft position and combined with a computer model of the surface topography to generate a perspective view. The final mosaic shows Olympus as it would be seen from the northeast. It's possible that volcanoes of such magnitude were able to form on Mars because the hot volcanic regions in the mantle remained fixed relative to the surface for hundreds of millions of years. (Image and caption courtesy of JPL/NASA).dem of volcano on mars


alba pateraAlba Patera,  the largest volcanic feature on Mars, lies to the north of the Tharsis region. It is over 1500 km wide, but only a few kilometers in elevation. Notice the concentric pattern of fractures. Alba Patera is most likely a large caldera or vent that has been eroded down to its current elevation. Some flows are visible on the flanks, but branching channels that may be a form of ash have dissected many of the flows.

larger alba patera

Lava Flows, Alba Patera

(46 N, 115 W; Viking Orbiter frames 252S01, 3, 5, 32, 34, and  36, high-pass spatially filtered orthographic version.)


lava flows on marsThe basaltic lava plains are the most widespread and voluminous features on Mars, covering over 60 percent of its surface. The plains have been compared to the huge flood basalts on the Earth and the lunar Maria, but are much more extensive. In the image to the left are Lava Flows, Elysium region, Mars created from a m osaic from Viking 651A08-651A12, processing by B. Fessler,LPI.


Plains-style volcanism is found on all the terrestrial planets and the Moon. The most notable example on Earth is the Quaternary volcanic fields of the Snake River Plain in southern Idaho, USA. Compare the two images below, which illustrate representative small shield volcanoes from Earth and Mars. Note that both are covered with wind-blown sand and dust. These volcanoes are similar in composition to large shields such as Mauna Loa and Olympus Mons, but differ dramatically in size.

Cottrell's Blowout shown to the left is a small shield volcano on the eastern Snake River Plain. The small plains-style volcano in the right image is located east of Pavonis Mons on Mars.

Note the similarities in shape, size and apparent relief. These volcanoes were erupted from very small batches of magma generated in lithospheric mantle. Small shields on the Snake River Plain are all basaltic, as are many other similar shields on Earth. Most evidence from Mars missions suggest that the small shields on Mars are also basaltic in composition. Photo credits: Cottrell's Blowout by Susan Sakimoto and Scott Hughes, Mars Orbital Camera (MOC) image by NASA/JPL/Malin Space Science Systems.



Tectonism on Mars

Though Mars does not have an active plate tectonic system like the Earth, it does show signs of lithospheric changes over time. Evidence for tectonism on Mars include the Tharsis and Elysium uplifts, possibly caused by upwelling mantle material as discussed earlier, and systems of fractures, graben, and wrinkle ridges associated with crustal uplift, extension, and compression.

Another example of tectonism on Mars is the canyons around the Tharsis uplift. The spectacular canyon system, known as Valles Marineris, has been modified by erosion, but is dominated by extensional faulting related to the nearby uplift. The canyons extend from the summit of the Tharsis bulge to the east where they eventually merge with the chaotic terrain south of the Chryse basin. (modified from a computer simulation by Walter S. Kiefer, LPI, and computer graphics by Amanda Kublal, LPI)

mantle convection

Valles Marineris

Valles Marineris

(Viking mosaic, image processing by the United States Geological Survey)

The following quote is taken from "The War of the Worlds", by H.G. Wells. Just for fun, visit this website: The War of the Worlds.

"That last stage of exhaustion, which to us is still incredibly remote, has become a present-day problem for the inhabitants of Mars. The immediate pressure of necessity has brightened their intellects, enlarged their powers, and hardened their hearts. ... And we men, the creatures who inhabit this earth, must be to them at least as alien and lowly as the monkeys and lemurs to us. The intellectual side of man already admits that life is an incessant struggle for existence, and it would seem that this too is the belief of the minds upon Mars. Their world is far gone in its cooling and this world is still crowded with life, but crowded only with what they regard as inferior animals. To carry warfare sunward is, indeed, their only escape from the destruction that, generation after generation, creeps upon them."

Evidence of Water on Mars

Mosaic of the head of Ravi Vallis, showing "chaotic terrain." Viking Orbiter image 606A56, centered at 42.5°S 92.6°W. Image processing by Brian Fessler (Lunar and Planetary Institute). Click on photos to learn more.

flow features


Teardrop-Shaped Islands teardrop shaped islands on mars







Canals ? ? ?

Since Percival Lowell first saw a system of ‘canals’ through his telescope on Earth in the late 1800’s, science and science fiction has been fascinated by the thought of Mars as a viable planet for colonization. Imaginations ran wild with the idea of flowing rivers and agricultural possibilities on the Red Planet, but explorations to Mars have dashed hopes of liquid water on Mars. frontispiece to mars by percival lowellThe current surface temperature on Mars ranges from 190 to 240 K. Liquid water cannot exist on the planet’s surface, yet many erosional features can be seen that indicate the former presence of flowing water. Dendritic river channels, dry river valleys, and outflow channels can be seen on Mars, which leads us to believe that surface water did once exist on Mars, but has since been locked up as ground ice and in the polar ice caps. There is also evidence of catastrophic flooding occurring on Mars many years ago. Teardrop-shaped islands and chaotic terrain attest to the outflow of huge amounts of water over the Martian landscape. The discharge of these floods has been approximated to be over 100 times the annual outflow of the Mississippi River! Perhaps the water was damned behind lakes or was the result of extreme artesian pressures at the surface.

(Frontispiece to Mars, by Percival Lowell)


Global Climate Change on Mars

Mars' past climate was apparently much wetter..  Go to this Scientific American article online and read about the possible history of Martian climate.  Think about the forces that created Mars' present and past climate.

Ground Ice

As discussed earlier, there is evidence of ground ice on Mars due to the shape and style of ejecta around craters. When the asteroid or meteorite hit the surface, it may have come into contact with ground ice a few to several hundred meters below the surface and caused it to temporarily liquefy and create an ejecta flow. Another line of evidence for ground ice on Mars is the system of spring fed channels that are created by removal of soft sediment layers by underlying water erosion. This is known as sapping and can also be seen in the polygonal cracks at the surface, which resemble those on the Earth caused by freezing and thawing of ground ice.

Polar Ice

At both the North and the South Poles of Mars are large ice caps that grow and shrink with the changing seasons. The ice caps consist of stacks of layered sediments and ice which are at least 4-6km thick in the north and 1-2km thick in the south. Cratered plains surround the ice caps and seem to extend beneath them, indicating that the ice covers the older craters and is, therefore, one of the youngest features on the planet. Valleys and channels cut into the ice forming a spiral shape (Figure 6.7) that curls clockwise close to the South Pole and counterclockwise close to the North Pole. These valleys reveal the internal layers of the ice caps. Farther from the poles the ice is smoother and is covered with huge dune fields.

wind on marsNorthern Polar sand dunes, image courtesy of NASA

During the Martian winter, the ice caps grow in extent and are covered with CO2 frost and ice. The summertime brings with it receding ice caps and sublimation of the CO2 ice. The Viking orbiters revealed that the permanent ice that remains at the North Pole is mostly water ice and sediment, further evidence that liquid water may have once existed on the Martian surface.

For more information about seasonal changes in polar ice caps, go to:



Eolian Features

Many of the surficial features seen on Mars indicate the strong effect that moving wind plays in shaping this planet. Wind streaks, huge sand dunes, deposits of loess, yardangs, and etched terrain can all be seen on Mars. As stated in your text, volcanism, tectonics, and running water have had only a slight effect when compared to the ceaseless winds that constantly scour the surface.  Visit The Winds of Mars Slide Set for an extensive look at the eolian features of Mars.

Assignment: Complete the study questions

1.  Examine the images below (click on either photograph to see larger images) of a Martian valley and a valley on Earth.  Briefly explain in a few short sentences the differences and similarities between these two terrains:

mars valley

Mars valley network (modified fromViking Orbiter Image 606A56, processing by Brian Fessler, Lunar and Planetary Institute)

dendritic drainage

Dendritic drainage on Earth, Republic of South Yemen, Rubh-al-Kali, photo courtesy of NASA.


2.  One of the major differences between Mars and Mercury or the Moon is the existence of an atmosphere. What is the composition and the relative pressure? What attributes of the Martian atmosphere, including critical wind velocity, temperature, etc., are required for eolian transport and the effects of running water?

3.  Think about the evolution of thought concerning the Martian surface from the Renaissance to the present.  Who are the important researchers, and what are the important dates and pertinent details about the features we see on the surface of Mars? Simply write these in outline format.

4.  List the similarities and differences between the Mars crater Yuty, Tycho crater on the Moon, and the craters in Caloris basin on Mercury.

5.  Is Mars geologically active?  What evidence for internal or external geologic processes forms the basis for your answer?

6.  The Martian floods probably had more than one cause.  What were the probable mechanisms for flooding on Mars, and what evidence exists for each mechanism?

Other web sites for information about Mars:

The Malin Space Science Systems website for resources and pictures of Mars.

The Red Planet: A Survey of Mars Slide Set One of our favorites! (from the Lunar and Planetary Institute)

Mars Surveyor 98 Home Page   Information from and about the Surveyor.

Mars Global Surveyor - Welcome to Mars! More on the Global Surveyor

Mars Pathfinder

On the Question of the Mars Meteorite

Module Study Locations on the Mars Map (from the Lunar and Planetary Institute)

Mars Exploration a timeline summary of Mars exploration from NASA and NSSDC.

The IMAGE / POETRY K12 Space Science Site  Home of Ask a Space Scientist.

Mars info - Way Cool Tools for Mars Exp Teachers Page

Viking Landers -

Pathfinder Pictures -

Mars Volcanoes - Volcanoes on Mars Slide Set (produced by the Lunar and Planetary Institute, Houston)

Mars Clouds - Mars Pathfinder - Clouds, Sunrises and Sunset...

NASA's Spacelink provides much more information on Mars and other planetary topics!

Below are websites related to Life on Mars:



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