Katherine Beal, C.C. Meneley Elementary, Minden, NV
FLIGHT PATHS OF ORBITING SATELLITES
Appropriate for grades 4-9.
OVERVIEW: One question frequently asked by students after viewing reports
of Space Shuttle launches, has to do with a large world map used at NASA
to display the path of the Shuttle as it orbits earth. On a flat map,
the orbit path appears as a series of wavy lines. Students often ask
why the Shuttle doesn't just fly in a straight circle around the earth.
PURPOSE: Teachers can use the following activities to help
students visualize the relationship of motion, time and space as
it relates to objects orbiting the earth.
OBJECTIVES: Students will be able to:
1. Track the path of an orbiting object on a globe.
2. Plot the path of an orbiting object on a flat world map.
3. Explain that an object orbiting earth on a plane will produce
a flight path which appears as wavy lines on the earth's surface.
ACTIVITIES:
PART I - Orbit Flight Path (To be done with a partner)
1. Make an orbit plane by cutting a round hole in the center of
a piece of oak tag board. The circumference of hole must be
equal to the circumference of the classroom globe. A metal
or washable plastic globe works best.
2. Draw lines on the orbital plane at twelve equal points around
the circular hole. (A quick glance at a clock face will help
students where to draw the lines.) The distance between each
line represents the distance an orbiter will travel in the
plane in one half hour. It takes the orbiter six hours to
circle the globe once.
3. Fit the orbital plane over the globe. Be sure the globe is
tilting 23.5 degrees. Once correct orbit speed and altitude
have been achieved, the balanced forces of inertia and
gravitational pull will keep the orbiter circling in a plane
around the earth. Engine thrust is no longer needed.
4. Imagine that an orbiter is moving along the plane in a
clockwise direction. With a finger, trace the path of the
orbiter as it circles the globe.
PART II - The Effect of the Earth's Rotation on an Orbiter's
Flight Path
1. Recall that the earth is not stationary beneath the orbiting
object. Rather, the earth is spinning toward the east on its
axis at a rate of one latitude line (30 degrees) per hour.
2. Using a washable marker, (Transparency markers are best) make
an X on the globe at any one of the orbital plane lines
touching a line of longitude.
3. Now imagine that one half hour has passed. The orbiter has
moved clockwise to the next orbital plane, but the earth has
also moved in the last half hour. One partner should steady
the orbital plane while the other partner rotates the globe
toward the east, (counter clockwise) to the next longitude
line. Mark the spot with an X and draw a line to connect
this X with the next one. This is the orbital path.
4. Continue step three above ten more times, connecting the X's.
Your orbiter has made two complete revolutions around the
earth. The path traveled by the orbiter has been on a
straight plane. Remove the plane and observe the flight path
on the globe. Because the earth is rotating at the same time
the orbiter moves along its plane, the flight path appears
wavy.
PART III - Plotting the Orbit on a Flat Map
Transfer the data from the globe onto a flat map by locating
points of longitude and latitude. Connect the X's. Note the
wavy lines that appear. Emphasize again that the orbiter did
not leave its plane.
RESOURCES/MATERIALS NEEDED: All described above.
Materials
Globe
Tag Board
Transparency Pen
World Map
TYING IT ALL TOGETHER: NASA usually tracks the path of man-made
satellites from a view point high above the orbiter, looking down
at the earth. Because the earth is spinning on a tilted axis,
objects orbiting the earth seem to have a wavy flight path. After
completing these activities, students should understand that the
combined movements of the earth and the orbiter result in what
appears to be wavy flight paths.
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John Kurilecjmk@ofcn.org