Mars

Martian Topography

Objective

Given high-resolution maps of Mars, students will explore the Martian surface and identify, measure, and describe the major geological landforms. These include large, individual objects (Olympus Mons and Valles Marineris), global features (the north-south dichotomy), and high-resolution surface images (erosion possibly due to flowing water).

If you are printing as you go for these labs, note that the answer sheet is a separate link. You can find it at Mars Topography worksheet (PDF). Another suggestion: please read completely through the instructions in each section before making your measurements. That way you are less likely to flounder.

Background and Theory

Mars, the third planet in our solar system, is similar to Earth in a number of ways. The coldest temperatures on the surface (-140 Celsius) are not far below polar temperatures here on Earth, and the high temperatures get up to a balmy 20 Celsius for short periods of time. Mars also has a thin but active atmosphere with clouds, weather systems, and winds that erode the surface. Both water and CO2 ice collect at the poles, giving Mars polar caps much like Earth's polar regions (see picture above).

There are some striking differences. First, the thin atmosphere prevents water from existing on the surface as a liquid, so there are no large oceans (only ice at the poles). Second, since the surface has not been recycled by plate tectonics, it provides a record of Mars stretching back to the late heavy bombardment. Finally, dust and wind dominate the erosion on Mars, with some dust storms reaching global scales.

You will explore some of the unique geological features on the surface of Mars, starting with two famous, large objects and dominant global features, and ending with high-resolution images at a much smaller scale.

Procedure

Using the appropriate images linked in the sections below, answer the following questions. Record your answers on the worksheet provided (PDF).

Part A: Volcanoes and Valleys

  1. Before you do any measurements or answer any questions, compare these two maps (Note: a new browser window will open, so be sure to return to this window when you go on to question No. 2.):

  2. Olympus Mons is the largest volcano in the entire solar system (at 24 km in height, it is about 3 times higher than Mt. Everest, at 8 km). It is surmounted by a complex summit caldera, and surrounded by a prominent scarp several kilometers high. Note the image at the right before taking your measurements. Make sure you measure the radius of the entire volcano, not just its central caldera!

    1. Using this image, find the radius of Olympus Mons. Your measured value will be in pixels. Convert this measurement to kilometers by using the image scale factor: 1.8 km/pixel.

      Your value will be approximate; measure from the center of the complex crater to the "prominent scarp" or cliff-like ledge that marks the edge. (Note: if you keep the "x" or "y" coordinate about the same for both clicks, you can avoid the use of Pythagorean's theorum at this step.)

    2. Using the fact that Olympus Mons is 24 km high, what is the slope of the volcano? (Remember: opposite/adjacent = tangent of the angle. The angle is thus the inverse tan of opposite/adjacent. Make sure your calculator is working in "degrees" and not "radians" or just use the calculator linked just below.)

      A calculator custom made to determine the inverse tangent and find the slope in degrees.

    3. Compare it to our national highway standard of a maximum 6% grade (about 3.5 degrees). Comment on your comparison by relating what it is like to drive up or down a 6% grade (slope), where you see truck run-outs, for example, or the absolutely steepest highway you've ever driven up or down (the Queen Anne counterbalance is steep; going from the waterfront up to Fourth Avenue in downtown Seattle is steep). The average grade to the top of Snoqualmie Pass is probably less than 1%!

  3. Valles Marineris is a rift valley formed when the Martian crust cooled. The entire valley is over 5000 km long (longer than the United States is wide).

    1. Using this image, measure the width of Valles Marineris (the image scale is 0.93 km/pixel). Use any criteria you wish, just state what you chose to measure as the "Valley."

      (Note: if you keep the "x" coordinate about the same for both clicks, you can avoid the use of Pythagorean's theorum at this step.)

    2. Because Mars is smaller than Earth and therefore has greater surface "curvature," if you were standing on one side of the valley, you would not be able to see the other side. (On a clear Mars day, you can see about 15 km away.) Recall pictures you have seen of the Grand Canyon, average width about 3 km. How does the view across the Valles Marineris compare? (Click on the image at the right to see the Grand Canyon.)

Part B: The north-south dichotomy

  1. Return the the MOLA Clickable Map of Mars. As soon as the first detailed images of Mars came back to the Earth, planetary scientists noticed the terrain in the north differed dramatically from the terrain in the south. Take a close look at the map yourself and see if you notice an overall difference between the northern and southern hemispheres -- BESIDES the differences in the color coding of the map, although that sure gives you some hints.

Part C: High resolution images of Mars

The Global Surveyor Mars Orbiting Camera (MOC) has radically changed our view of Mars. The high resolution camera returns images where the smallest visible feature is about 2 meters in size (about the size of you!).

  1. All of the images from MOC are available from Malin Space Science Systems. Take a moment to check out some of the images.

  2. The polar regions of Mars are of great interest to scientists. The poles record, in layering of ice and dust, periods of climate change on the red planet. These layers are about 10 to 100 meters thick. During the history of Mars, the climate has changed several times such that different layers have different amounts of ice and dust, changing their appearance. Look at these images and page down to read the explanation. If each layer represents 100,000 years of accumulated ice and dust, approximately how much of Mars' climate history is recorded in these layers? Recall (or find out) how atmospheric scientists use cores drilled in Antarctica for their studies. What do these cores (sometimes kilometers in length), tell us about the history of the Earth? Here we have another example of how comparative planetology works. (If we could only get to Mars to drill!)

  3. Early in the year 2000, researchers discovered what appear to be recent evidence of flowing water on Mars. Take a look at this sequence of images and answer the following questions.

    1. Identify the alcoves, channels and aprons identified in the images. Using MOC2-234 as a model, draw and label a schematic (geologic map) of a gully.

    2. Pick one of the other images from the surface of Mars. Draw a geologic map of the image and identify the same features. Be sure to indicate which image you chose.

    3. Compare these two images of Mars and Mt. St. Helens. Name one similarity and one difference you see between these images. Make sure you read the information contained beneath the images very carefully (NASA provided).

    4. What is the main problem with the "recent flowing water" hypothesis used to explain these features? (Hint: recall Mars' atmospheric pressure.)

Part D: Summary

Pretend that you must give a two-minute summary on the major features of Mars. Write your short talk here in two-to-three paragraphs.

 

Last updated on: