An activity you can use in the classroom
In 1976, the United States sent spacecraft Viking 1
and Viking 2 to Mars. The landers on the spacecrafts
had instruments that could detect any sign of life in
the Red Planet's soil. What were the instruments looking for? When living
things metabolize food into energy, they produce waste,
some of which is gas. The Viking landers tested Mars'
soil by mixing it with nutrients and measuring the subsequent
release of gas.
- If there were life in the soil, scientists would
have expected a continuous production of gas.
- If there were no life, either no gas would be produced
or a just a small amount would be produced initially.
(This initial chemical reaction would not last because
the chemicals in the soil would be used up, while
a living organism would continue to metabolize the
food as long the supply lasted.)
In this experiment, you'll duplicate the tests the
Viking landers conducted in their search for life on
Mars with this experiment. 
- 3 glass jars
- enough sand to fill each jar one-third full
- masking tape (for labeling the jars)
- 2 teaspoons of salt
- 2 teaspoons of yeast
- 2 teaspoons of baking powder
- A large pitcher
- 1/2 cup of sugar
- 2 cups warm water
- Fill each glass jar one-third full of sand, and
attach a masking tape label to each jar. Mark each
label with a different color ? red, blue, and
green.
- Add the salt to the red jar, the baking powder to
the green jar, and the yeast to the blue jar.
- Refrigerate the jars overnight to simulate the cold
Martian surface.
- The next day, mix the sugar and warm water in the
large pitcher until the sugar is completely dissolved.
- Pour equal amounts of the sugar water into each
of the labeled jars. Then place the jars in a shallow
tray and set them aside.
- Watch the jars carefully
for any signs of organic or chemical reactions, noting
your observations on the attachedworksheet.
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