If we are to compare Earth and Mars, we must learn much more about the historical “geology” which took place on both planets . Our satellites and landed robotic probes, now and in the future, collect information which may lead to answering this exciting mystery. New understandings of Martian history are being written today, as a steady stream of information pours back to us. A new view of Mars is forming. Is this view of Mars we now see, a picture of Earth’s past, two billion years ago, or is it Earth’s future?

Tutorial Topics
MGS - Mars Global Surveyor
Launched in November 1996, the space craft traveled for 10 months to reach Mars followed by a year of positioning. In March 1999 its mission will officially begin. The Mars Orbiting Camera - MOC, will produce a photographic record and MOLA, the Mars Orbiter Laser Altimeter, will map the Martian topography. MGS will fly around Mars in a near circular orbit at an altitude range of 375 km to 445 km above the surface. The orbital period will be 117 minutes, repeating approximately every 7 Martian days.

MOLA -Mars Orbiter Laser Altimeter

An altimeter measures altitude, the height a plane or satellite is above a planet’s surface. A laser altimeter uses focused light pulses to do the same. MOLA’s solid state laser fires short pulses of infrared light 10 times per second at the surface of Mars and measures the time for the reflections to return. Upon return to the satellite, a telescope focuses the light scattered by the terrain and possibly clouds, onto a series of detectors. By knowing the speed of light, the satellite’s position and its height above the planet, one can map the surface based on the return time of the pulse. The heights of mountains and the depths of valley’s will be revealed to a precision of 40 centimeters. Laser altimeters have a small footprint on the planet’s surface. MOLA’s beam is only 130 meters wide. Each track along the planet’s surface measures elevation continuously.

“Link to see an exploded view of MOLA”


“First MOLA pass provided improved accuracy of Martian topography.”


“Profiles of first 18 MOLA passes.”


Viking Missions to Mars
In 1976 two space craft were sent to map Mars and then land to take surface pictures and conduct tests. These were Viking I and II. Prior to these missions the Mariner 9 craft was sent to the planet on a mapping mission. Mariner images where used to select Viking landing sites. Viking images became the basis for determining the landing site of the Mars Pathfinder in 1997. They were made by way of radar altimetry.
While there are many forms of radar altimeters, they differ from laser altimeters in two ways;
-their footprint is large- tens of kilometers across
-images are overlapped and the results averaged
Another distinguishing factor between radar and laser refers to the electromagnetic spectrum.




Recall that wavelengths shorten toward the gamma ray end and length on the radiowave side. Radar altimeters most often operate in the high microwave bands and laser altimeters in infrared wavelengths. Greater detail can result by use of a shorter wavelength.


Vertical Exaggeration
In our investigation we will be working with topographic data returned from the MOLA instrument. Data sets are often compressed horizontally so they take less space and graph more easily. We will need to keep this in mind. The graph below serves as an example. Note the V.E. 100:1 . This ratio means that the vertical is exaggerated 100 times for each unit on the horizontal. For example track 24 has a huge spike structure. This is actually the profile of Olympus Mons. This broad based shield volcano returns to its true shape when you add 100 units to the horizontal for each 1 on the vertical scale.

Scale of Profiles
Another item to remember when working with graphs is to watch the scale on the y-axis. As one decompresses the data, each zoom in, changes the scale.



On the graph above, each y-axis tick mark represents 1,000 meters. On the one below each mark stands for 100 meters.



Note on both profiles that latitude is represented on the bottom. While not labeled, the longitude is displayed at the top. Note the zero on the first profile’s y-axis. This represents the “areoid.” On Earth the “geoid” is the hypothetical mean elevation of Earth’s surface, which coincides most of the time with mean sea level. For a planetary reference point on Mars, science calculates the areoid. To express it simply, it’s an average of the highest and lowest elevations. Negative values on this axis is below the areoid It is a lowland, but does not mean below sea level. It does not correspond to “what the sea level was when Mars had an ocean.”

Basics of Mars Erosional and Tectonic Features
Our point of reference for the study of Mars will be Earth features.



Alluvial Fan (side view)

Normal Fault (side view)

Escarpment (side view)


To learn about these structures click on the links below.
Slumping

Sheild Volcano

Valles Marineris

Channels


Procedure
Orientation
1. Use hardcopies of the six “Selected Profiles” that can be printed from the links in the profile number section below.
2. Study each profile to identify the following tectonic and erosional features.
3. Neatly bracket each structure you find in pencil. Draw a line to the margin and label the structure.

Profile NumberAerological Features To Find
p35crater
escarpment
p35three previous signs of water
2 old river channels
1 young
block fault
p21river channel
slumped wall
p20an erosional feature
p24identify the large structure find the hummocky terrain
p25You make the call. What structures do you see here?

The Latitude / Longitude Treasure Hunt
Teacher Note:
Teachers should work through the lab, identify the 6 Viking Maps that are needed and print them on a laser printer. If you laminate them they can be used many times by students using water based transparency markers. Since the lightest shadow may represent a crater, photocopying multiple copies will diminish resolution. Students need to work from an original.

Tip - Keep This In Mind
The MOLA flight path is not true north to south. It flys 1.5 degrees on the diagonal from NE to SW.

In this part you will use the six Selected Profiles of MOLA track data. Try to locate each on the Viking atlas images. You need to have a copy of each Viking Map and the “Treasure Hunt Summary” sheet.

1. Book mark the following website of the Mars Viking Atlas.

2. First time user- read through the introductory information.
3. Within the blue box is an active gridded atlas of Mars. You may wish to cruse the planet, clicking and zooming in on any zone. This way you can learn to use the atlas and become familiar with surface features.
4. When you are ready to begin the treasure hunt, follow the lat./longs. and click and zoom in on the atlas. Then study the profile and try to locate the features represented on the profile. You are trying to determine the flight path taken by the satellite.

Note: The profile covers only a small segment of the Viking image. The ‘p’ before each, stands for pass. You may ignore the ‘v’.

5. Answer the questions on the Treasure Hunt Summary as you work with each profile.

Profile Number Aerological Features To Find
p35 crater
escarpment
p35three previous signs of water
2 old river channels
1 young
block fault
p21river channel
slumped wall
p20an erosional feature
p24 identify the large structure find the hummocky terrain
p25You make the call. What structures do you see here?


Ground Truthing
1. To ground truth you will now check your efforts at locating areological features on the Viking images, by using images with the flight paths overlayed.
2. Book mark the Geodynamics website.
3. Scroll down to the- “First Set of MOLA Pass Maps”.
4. We will walk through the first one together. Click on pass 35. Scroll down to the list of latitudes. Our profile segment lies between 29.78 and 30.30, so choose 20-32.
5. The dashed black line is the MOLA flight path. Use the lat./long. to find the structures in the profile.
6. Hold your Viking Map, where you drew the flight path, up to the screen and check your skill at reading profiles, areological features and lat./long.
7. Now repeat this process for the other five profiles.

Teacher Note:
Friendly competition between lab teams could be created. Use a metric rule to measure, on the screen, the distance the team is off from the plotted answer. Total all six profiles. Low “error total” wins.

Resources
The following sites are good sources of general Mars information.
The Center for Mars Exploration
Mars Introduction
Mars Academy
Daily Martian Weather Report

Mars
Mars Fact Sheet


Collection of recent images.
Malin Space Science Systems
Geology of Mars
Mars Team On Line

Extension Activities
1. The Not So Grand Canyon
Action: Graph profiles of the Grand Canyon and Valles Marineris
Goal: To recognize the extreme size of features on Mars, when compared to the planet’s size.
Grade Level: 9-12
Materials:
Procedure:

2. Craters Have a Story To Tell - Can You Read It?
Teacher Note- This data is fresh from space and there is no established scale as yet. Remind the students of this and watch the y-axis. By next year a standard scale should be in place.
Action: Analyze four crater profiles.
Goal: To provide a basic first exploration of Martian craters.
Grade Level: 9-12
Materials: metric ruler, protractor, copies of 4 crater profiles and the
Crater Activity Student Sheet
Background:
“Complex craters” form when gravity causes the walls of larger craters to collapse downward and inward forming a central peak.
Vocabulary:
1. central peak- a mountain found in the center of large craters, formed
by a “rebound” of the rock at the impact site.
2. crater- a usually circular depression in a surface caused by an impact
3. ejecta- material through out of the crater
4. ejecta blanket- ejecta tossed out at low speed, laying like a blanket
around the crater
5. floor-bottom interior of the crater, it is flat in the larger craters
6. rampart (rim)- height of crater wall, measured from the outside;
formed by the outwards and upwards compression of the crater
walls, not ejecta
Links-Astronomy PictureCraters Iturralde Structure
Procedure: (Complete the Crater Activity Student Sheet as you
proceed.)
1. Collect the following measurements.

	Crater Depth Left Wall AngleRight Wall Angle 1 2 3 4

a. Use a metric ruler to measure the depth. Move to the y-axis scale
and convert to meters.
b. Use the protractor to measure the left and right crater wall angles.
2. Compare the crater walls for symmetry.
3. Determine the steepness of the crater walls.
4. Compare the profile to the top view image from the Viking Atlas.

3. Calculating Slopes
Action: Students will use MOLA profiles and calculate slope.
Goal: To understand how slope can be calculated from Mars profiles and compare this to the more simple method they can use to measure Earth slopes.
Grade Level: 11-12 (Higher Math Functions Required)
Materials: calculator, metric ruler, slope profiles

Procedure:
1. Provide students copies of the slope profiles.

	2. Steps Example A. Draw slope line with ruler from|-----------------| point to point. B. One inch = 0.8o of latitude. C. Determine the line length. 3.75 inches D. Calculation - solve for degrees of latitude3.75 in. X 0.8o = 3o E. Convert degrees into meters. degrees X constant = meters3 X 59288 = 177,864 meters F. Determine the height. Use a ruler to help you measure the height from the profile.height= 1200 meters G. Take the tangent height1200 = 0.0067 length177,864 H. Calculate the arctangent of above answer to get degrees of slope.Slope = 0.4o Follow these steps to calculate the slopes.

3. Summary
To put the meaning of slope into perspective, students could take measurements on a hill at the school campus or near by. Then do slope claculations. Have students write out their plan on how to calculate the slope of the hill. There are numerous methods. Guide them to one that is correct.

4. Student Follow Up
Research the following slopes.Source
-average slope of interstate highways State Highway Engineer
-greatest practical slope on interstate highway“
-average rail bed slopeRailroad Engineer
-greatest possible railroad slope “
-desirable field slope for various cropsLocal Soil Survey or
corn National Resourse
hayConservation Service
soybeans

4. Laser Altimeter Lab
Action: Students simulate the functioning of an altimeter by timing the velocity of a ping pong ball.
Goal: To learn through a hands-on experience the basic concepts behind the use of a laser altimetry.
Grade Level: 9-12
Procedure: click here

5. You Be The Planetologist
Action: Team brainstorms a hypothesis to the assigned question.
Goal: To give students opportunity to review Mars information and to polish team problem solving skills.
Grade Level: 9-12
Materials: wall chart paper, markers
Procedure:
1. Each team seeks to produce their best proposed answer to the
question;
Based on what you know of Earth’s geology and what you have learned about Mars areology, what is your teams explaination for what forces or processes lead to the creation of such large surface structures on Mars?
2. The time limits for such an activity is highly variable based on the level of detail you wish or their knowledge base.
3. Teams could rough out their thoughts on scrap paper and report their polished thoughts in wall chart form on large paper.
4. Later they should verbalize and defend their thoughts. As teachers we will accept any proposed reason that does not contradict taught and known facts.


Coding
Maryland Core Learning Goals (Science)
Goal 2 Extectation- 1:1:1, 1:1:2, 2:2:1, 2:2:2, 4:4:4, 4:4:5, 7:7:3
National Science Standards (9-12)
A. 1,2,3,4
E. 1,2
G. 1,2,3
National Geography Standards
Standard 1, 7
National Mathematics Standards
6.1, 6.3, 4.3, 6.1

Teacher Resources

Credits
Scientist- Stephanne Stockman-GSFC
Teachers- Dave Hixson
Tom Albert