Where can NASA find water on Mars?

A unifying theme for NASA's missions to Mars has been to "follow the water." At first, scientists found only traces of water vapor in the thin atmosphere and exposed water ice on the northern polar cap.

In 2002, Mars 2001 Odyssey scientists excitedly found large amounts of water ice buried by a thin layer of soil around the Martian poles. They estimate high concentrations of ice, perhaps as much as 80% by volume, are within half a meter of the surface. In 2008, the Mars Phoenix Lander will arrive at the northern plains of Mars and sift through the top ten centimeters of soil to verify this measurement.

Is Martian soil in these polar regions more like dirt with a little water filling the pore spaces or more like dirty ice?

To analyze soil and frozen soil samples. To determine which sample is most like the sample scientists expect to find on Mars around the Martian poles.

Prepare the following (for the group) PRIOR to the experiment:

Make frozen dirt/water icicles created from the same soil samples the students will analyze. Some students will receive icicles from sample A and some will get sample B icicles. Create your own "measuring cup" by marking milliliter (mL) measurements on an empty 10 ounce (oz) wax paper cup. Use this cup to create icicles with these approximate ratios:

icicle 1: 10% water to soil by volume (Using a graduated cylinder, add 25 mL crushed ice and water to 225 mL soil. Stir to mix. Freeze.)

icicle 2: 50% water to soil by volume (Using a graduated cylinder, add 125 mL crushed ice and water to 125 soil. Stir to mix. Freeze.)

icicle 3: 80% water to soil by volume (Using a graduated cylinder, add 200 mL crushed ice and water to 50 mL soil. Stir to mix. Freeze.)

Now would be a good time to let students see that a volume of water changes when liquid water becomes water ice. Ask each group to pour some water into a wax paper cup. Have them mark the water line with a permanent marker. Put these cups in the freezer as controls. Let students observe the changes in volume.

For each student:

hand lens

paper plates

Data Collection Charts

For each group:

two different soil samples (gravel, sand, or clay)

Mark these samples, sample A and B.

Part One:

1. Practice using a hand lens.
   
2. Divide the paper plate into halves, marking one half "A" and one half "B."
   
3. Look at the small soil samples you receive. Use your senses of sight, touch, and smell to observe the soil. Consider using terms such as grainy, gritty, smooth, rough, wet, dry, musty, and so on.
4. Record your observations in the data chart.
   
5. How do the soils compare? How do the textures compare? Which particles are larger? How do the colors compare?
   

Part Two:

6. Each group will receive one icicle sample. Mark the volume of the icicle (the height) with a permanent marker. Peel away the wax paper cup so that you can observe the sample and record your observations. Can you identify whether the icicle contains sample A or sample B dirt? How?
   
7. How can you measure the volume of the icicle? Use a graduated cylinder and a second paper cup to calculate the icicle's volume.
   
8. How would this measurement change when the icicle melts? How does the volume of water change when water freezes and becomes ice?
9. How can you determine the amount of water and dirt that make up the icicle? As a team, design your own experiment to find out. How might you safely speed up the melting process? Be sure you record the time it takes for the icicle to melt.
   
10. Once the icicle melts, how can you separate the materials? What tools do you need? What must you do to be sure that water is not trapped in the dirt?
11. Compare your findings with other students. What calculations will determine the percentage of dirt to water based upon volume?
    





1. How did the two dry samples compare? What terms did you use to describe these samples?
   
2. Does the difference in the ratio of dirt to water change the melting time of the icicle? Which icicles melted first?
   
3. What percentages of ice to dirt do scientists expect to find at Mars's North Pole? Which icicle samples are most like these percentages?
4. From your observations, is Martian soil more like dirt with a little water filling the pore spaces or more like dirty ice?
   




1. What other experiments might you conduct with the icicle samples?
   
2. Is there a place on Earth similar to the North Pole of Mars? What can scientists learn from studying this place on Earth BEFORE traveling to Mars?
   

Many thanks to Dr. Bill Boyton and the Mars Odyssey Gamma Ray Spectrometer Team, especially John Keller and his team of master teachers, for their help with this activity.