Student Activity #2

Large distances cause a communication time delay

RATIONALE:

Scientists (and the public) would like to explore Mars in detail. We want to search for signs of water and the possibilities of life. We need a "tool" to search for us because we do not (yet) have the capability to send people. NASA will send a "rover" that is a vehicle that can move on the surface of Mars and study its rocks. The rover is named Sojourner.

In order for Sojourner to be able to investigate Mars, it must be able to understand commands given to it from Earth. Commands will take from 5 to 20 minutes to reach Sojourner once the command is sent. It will take another 5 to 20 minutes for confirmation to reach Earth from Sojourner. The Rover Relay will attempt to let the students experience the difficulty involved in communicating commands to a rover, wait for the rover to perform the commands, and receive confirmation.

SET UP:

This game should be played outdoors in a large field so the teams have room to spread out and operate their "robots." The class will be divided evenly into relay teams and each team will stand in a straight line. There should be ample distance between teams. The teacher will lay out objects for each team (one object for each team member) in a random pattern. Each team should have the same objects and the objects should have similar placement across the teams.

PROCEDURE:

1. The first person in line is the robot.
2. The last person in line is mission control.
3. The other people in line represent the "time delay."
4. All teams begin at the same time.
5. When the teacher says "Begin," mission control decides on an object to have the robot retrieve. Mission control needs to decide what commands need to be given to the robot, one command at a time, in order to have the object retrieved.
6. Mission Control whispers one command to the person next to them, that person repeats whispering the message to the person in front of them, and so forth until the command reaches the robot.
7. The robot performs the command and tells the person behind him or her that he or she has done so. That person informs the person behind him or her, and so on, until the message reaches mission control.
8. Mission control sends another command in the same manner.
9. When the robot has retrieved the object, he or she goes to the end of the line and becomes mission control. The person at the head of the line now becomes a new robot.
10. Repeat until all objects have been retrieved.

ANALYZE

When the game is over, return to the classroom and discuss what happened. How could your team improve its directions to the robot? What are the implications for Sojourner? What are the similarities and differences?

Discuss what things worked for communicating effectively and efficiently with your robot. What are things that scientists and engineers need to consider in order to communicate with Sojourner?

Extending this activity:

Play a different version Rover Relay with another class using e-mail. E-mail a direction for someone in the other class to follow. Choose an action that requires a few steps and has a definite "endpoint," such as taping a note saying "Science Rules" outside the classroom door. After they have followed your direction, they will send e-mail back to you, letting you know that they have completed the task. Keep track of how long it takes to communicate this way. How long will it take scientists to send a message to Sojourner? How long will it take for Sojourner to follow directions and respond to the scientists?

• Student Activity #1: Comparing Earth and Mars
• Student Activity #3: The Design Team
• Student Activity #4: Compare NASA's design with yours
• Student Activity #5: Wrap-Up Activity Suggestions
• Teachers' Resources