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This material was developed for the Live From Mars project by Passport to Knowledge. Live From Mars was a precursor to Mars Team Online.


Teachers' Guide

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Activity 3.3: Detecting Magnetic Materials in "Martian" Soil

Teacher Background

Pathfinder's experiments will begin even as the lander is descending through the thin Martian atmosphere. The spacecraft will look at the atmospheric structure and perform weather experiments--sampling pressure, temperature, and density of the atmosphere. After landing it will periodically look at the weather with its instruments, while the lander's camera records dust particle sizes and shapes, as well as panoramas. The camera has multiple color filters that will be used to figure out what minerals occur on Mars.

The Alpha Proton X-ray Spectrometer (APXS), an instrument on the Rover, will help determine the composition of the surface rocks. Those investigations will represent a reference point, or "ground truth" to help scientists calibrate remote-sensing information collected from orbit by MGS and successor spacecraft. A series of small magnets and a reference test chart will help test the magnetic component of Martian dust and any movement of the dust over time.

Objectives

  • Students will simulate some Pathfinder experiments by devising methods of collecting and measuring magnetic substances in pseudo-Martian soil.
  • Students will run controlled experiments to test the efficiency of each method and evaluate the efficiency of various collection methods.

    Materials:

  • bar magnets (1 for each team of 3 to 4 students)
  • 1 box plastic sandwich baggies
  • white construction paper
  • petri dishes (4 per team)
  • metric scale (1 per team)
  • 1 bucket clean white sand
  • 1 qt. iron filings
  • measuring cups
  • hand lens (1 per team)
  • Data Collection Table (student made)

    Before class, make synthetic Martian soil in following mixtures, labeled "A", "B", "C", and "D":

  • Activity 3.3 Teacher Demonstration Carefully place 1/4 cup "Martian" soil in clean petri dish. Examine with a hand lens. Record total weight. Cover the end of a bar magnet with a plastic baggie and demonstrate one possible method (scraping the magnet through the soil) to separate the magnetic substance from the non-magnetic substances in the "Martian" soil. Place magnetic substances collected in clean petri dish. Repeat procedure until you feel all magnetic substances have been removed from sample. (Ask students whether there should be a limit on the number of times you can repeat this procedure.) Brainstorm other methods (e.g. pouring the soil over the magnet, or spreading out the soil in a thin layer and passing the magnet over it). List ideas on chalkboard and allow time for students to discuss the pros and cons of each method. List the materials that will be on hand for their experiment and the need for careful measurements, observations and recording of data. Each team will need to construct a data table and formulate a procedure for conducting a well-controlled scientific investigation.

    Mixture A
    3 3/4 cups white sand
    1/4 cup iron filings Mixture A = 6.25% magnetic
    Mixture B
    3 1/2 cups white sand
    1/2 cup iron filings
    Mixture B = 12.5% magnetic
    Mixture C
    3 cups white sand
    1 cup iron filings
    Mixture C =25% magnetic
    Mixture D
    3 1/2 cups white sand
    1/2 cup soil
    Mixture D = ?% magnetic

    Engage

    Explain to students that they are to design a method to separate and measure percentages of magnetic material found in 4 different samples of "Martian" soil.

    Vocabulary
    atmosphere
    conclusions
    hypothesis
    petri dish
    procedure
    observations
    Scientific Method
    spectrometer

    Explore

    Procedure

    1. Complete Teacher Demo as described above.

    2. Allow time for each Mars Mission Team to design an experiment that tests 3 different methods of separating magnetic substances from the four samples of Martian soil. Each experimental design should include the following:

    statement of purpose, hypothesis, materials list, procedure,
    record of observations, and conclusion.

    3. All teams complete their experiments, recording data and preparing a lab report. Individual teams report findings and results to class.

    Younger students might follow the sample procedure outlined below:

    a. Prepare a soil sample that contains a known amount of magnetic material.
    b. Try various collection methods and weigh the amount of magnetic material collected with each method.
    c. Calculate the efficiency of each method; i.e., the weight collected divided by the weight originally present. Does each collection method approach 100% efficiency? Examine the separated magnetic substance with a hand lens. Was any white non-magnetic sand collected with the dark magnetic material? Why?
    d. Repeat the experiment a few times. How reproducible are your results? How accurate are they?
    e. Are your results consistent for each soil sample?
    f. Did your experiment support your original hypothesis? What are your conclusions?

    Expand/Adapt/Connect

    online icon Find out more about how Pathfinder actually assesses the magnetic properties of true Martian soils. (Hint: no baggies are involved!) Look on-line. Send questions to Researcher Q&A and post replies on your Bulletin Board.

    Research the Alpha Proton X-ray Spectrometer. How does it work? What data will it send back to scientists on Earth? Why is this data important and how will it be used? What will the Alpha Proton X-ray Spectrometer not be able to do?

    social studies icon If you became a member of the "Planet X Mission" Planning Team, what requirements would you put on a soil sampling device? Record your ideas in your Mars Mission Logbook.

    language arts icon You are the Chief Scientist in the lab that will be investigating samples returned from Mars in 2003 (or thereabouts.) Write a detailed Laboratory Procedure that provides guidelines for the non-contamination of the returning samples by terrestrial material--and vice versa, keeping Earth safe from Mars!

    How Pathfinder's rover got its name:
    Sojourner

    The name Sojourner was chosen for the Mars Pathfinder rover after a year-long, worldwide competition in which students up to 18 years old were invited to select a heroine and submit an essay about her historical accomplishments. The students were asked to address in their essays how a planetary rover named for their heroine would translate these accomplishments to the Martian environment.

    ...Valerie Ambroise, 12, of Bridgeport, CT, submitted the winning essay about Sojourner Truth, an African-American reformist who lived during the Civil War era. An abolitionist and champion of women's rights, Sojourner Truth, whose legal name was Isabella Van Wagener, made it her mission to "travel up and down the land," advocating the rights of all people to be free and the rights of women to participate fully in society. The name Sojourner was selected because it means "traveler."

    JPL scientists and engineers working on the Mars Pathfinder project and Planetary Society staff members reviewed the 3,500 total entries received from all over the world, including essays from students living in Canada, India, Israel, Japan, Mexico, Poland and Russia. Nearly 1,700 of the essays were submitted by students aged 5 to 18 years old.

    Suggested URLs
    http://mpfwww.jpl.nasa.gov/mpf/sci_desc.html#APXS
    http://ceps.nasm.edu:2020/RPIF/MARS/rpifmars.html


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