![]() Swing the Doppler ball in a vertical orbit, so that the orbital plane is perpendicular to the floor. Most students with good hearing should be able to discern the shift in this circumstance even if they could not when the ball was being tossed. Have them describe what they are hearing. Ask students if they can hear a Doppler shift. Resume the demonstration by orbiting the Doppler ball horizontally above your head, like a lasso, while you stand in the center of the circle formed by students. Tie a one-meter length of string securely around the Doppler ball so the ball will not be at risk of coming loose when swung at high speed.Ask students to explain why students in the line of flight notice the Doppler shift more than those off the line of flight.Those off the line may notice a much diminished effect. The amplitude (volume) change is apparent as the ball gets closer or farther, but the Doppler shift can also be very noticeable as the ball goes by students along the line of flight. Throw the Doppler ball to different students around the room, encouraging all students to listen with each throw. Have students stand around the perimeter of the room, or take the class outdoors to form a large circle.Credit: NASA/JPL-Caltech | + Expand image This animation shows how the DSN compares data obtained from multiple antennas to identify a spacecraft's position. The Canberra Deep Space Communication Complex near Canberra, Australia.The Madrid Deep Space Communications Complex near Madrid, Spain.The Goldstone Deep Space Communications Complex near Barstow, California.The DSN consists of three antenna facilities spaced at roughly equal distances from each other (about 120 degrees apart in longitude) around the world, including: It also supports some Earth-orbiting missions. The DSN supports interplanetary spacecraft communication, radio astronomy, radar astronomy, and related space-science observations. NASA’s Deep Space Network, or DSN, is an international network of antennae used to communicate with spacecraft. Consider having them use a smartphone sound frequency analyzer app such as Phyphox to discern pitch differences. Students who are hard of hearing may have difficulty with this activity.If students cannot discern the change in pitch, skip to Step 6 and rotate the ball at sufficient speed for students to be able to hear the change. ![]() ![]() The faster the ball is thrown, the easier it is to discern the change in pitch.Part of this activity requires students to throw a ball, which should either be conducted outdoors or in a safe indoor environment.Wrap a heavy-duty rubber band or two around the ball to secure the opening so the buzzer will remain inside the ball when it’s thrown.Insert the buzzer into the center of the ball.Using scissors, cut toward the center of the ball to create an opening for the buzzer.Turn the power switch on to verify that your buzzer sounds.Insert the battery into the battery holder and close the lid.If your battery holder has a power switch, make sure it’s in the “off” position.Use a small amount of electrical tape to secure and insulate the connection. ![]() ![]()
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