# Labs from Chicago, Fall 1993 : What Keeps A Satellite Up?

Dr. Jim Sweitzer
Labs written for the CARA Space Explorers, Fall 1993

This is meant to be handed out to the students.

## Instructions

Meet in your group. Your librarian should first read this activity aloud to the group. Each of you should keep a worksheet for yourself, but the group's recorder is responsible for handing in a completed copy to me. This is what your group will be graded on. The organizer should make sure the group stays on track, everyone has input into the answers, and that everyone can say the answers to the questions.

1. Before you do any investigating, your group should try to frame a short explanation of what keeps a satellite up. Write it below.

2. Using the marble and cup, investigate the concept of momentum. Give the marble a push on the carpet and on the table top. Then answer these questions:

a. When you release the marble does it travel in a straight or curved line?

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b. What is the difference between releasing it on the carpet or the table?

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c. Can you explain this difference?

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d. What would happen if you were in space far from the Earth?

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3. Now, using Dumbo* the Satellite, perform the following short investigations.

a. What if Dumbo* is just placed high above the Earth with no momentum at all and released? Describe what happens.

b. What pulls Dumbo* toward the Earth?

c. Suppose you give Dumbo* a small amount of momentum exactly tangent to the Earth's surface? Describe what happens.

d. What two initial conditions are necessary when starting a satellite to keep it in orbit? Try them out first using Dumbo*, then write them down below:

e. If you have Dumbo* going in a orbit, does the rotational direction or speed of the Earth make any difference. Try some different cases, then write your observations below.

4. Now, go back to the first question that you tried to answer at the beginning. The group should now write a short paragraph answering the same question, but now after having done questions 2. & 3. Write the group's consensus paragraph below.