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NOVA scienceNOW: Space Elevator
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Viewing Ideas
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Before Watching
Familiarize students with terms related to the space elevator. Have
student pairs find the definitions for the following terms in their textbook,
on the Internet, or from another resource.
geosynchronous orbit: When a satellite orbits 22,000 miles above Earth's
surface, it travels at a speed that allows it to stay in the same position
relative to Earth.
prototype: An experimental working model of something that is typically
used to base future models on.
buckyball: An informal name for buckminsterfullerene, a form of carbon
composed of 60 atoms. A molecule of buckminsterfullerene looks similar to a
round soccer ball—thus the name "buckyball." The molecule is named for
Buckminster Fuller, an architect, author, and inventor who designed a
structure—the geodesic dome—that looks much like the carbon
molecule.
carbon nanotubes: Nanotubes are cylindrical forms of carbon with novel
properties. They are good conductors of heat and electricity and have
extraordinary strength, far greater than steel. Explore carbon in everyday life. Carbon is the most versatile element
in the periodic table. It is the foundation of organic chemistry and is the
basic element in plant and animal cells. It is an essential component of
plastics and many pharmaceuticals.
Divide the class into three groups. Assign each group one of the sets of carbon
compounds below to research. When they have completed their research, have each
student group make a poster and present what they learned to the class.
Group 1: Diamonds, coal, graphite
Group 2: Oil, natural gas, plastics, pharmaceuticals
Group 3: Proteins, fats, carbohydrates
As an extension, ask students to research how or why carbon can exist in such
dramatically different forms, colors, and characteristics. (Carbon has four
bonding positions in its outer electron shell and is unique in its ability to
form double and triple bonds. Carbon can form incredibly complex chain
molecules, rings, sheets, lattices, buckyballs, and tube structures. There are
more types of compounds formed with carbon than with any other element.) Calculate and compare scale distances. The carbon nanotube space
elevator would transport materials into geosynchronous orbit around Earth. How
does the distance of this geosynchronous orbit compare to the distance of space
explored by a space shuttle? Give students the Size and Distance Stats below
and have them calculate, then show, the scale of the two orbits. (Students
should calculate map scale first. For example, if the globe is 10" in
diameter and Earth's diameter is 8,000 miles, then 1" = 800 miles. The space
shuttle would orbit only 1/4 of an inch above the globe's (Earth's) surface. A
satellite in geosynchronous orbit, or the final stop of the space elevator,
would be 28" above the globe.) Now have students use sheets of paper to
make models showing the scale. Place the sheets side by side for comparison.
Size and Distance Stats
Earth is represented by a 10" globe (or use whatever size globe you have)
actual diameter of Earth = 8,000 miles
space shuttle orbit = use an orbit of 200 miles above surface of Earth ( Note:
The space shuttle's orbit ranges from 115 to 250 miles.)
geosynchronous satellite orbit = 22,000 miles above surface of Earth
After Watching
Explore the materials needed for making carbon nanotubes (Part 1), then
compare the theoretical model of the space elevator to actual models (Part 2).
(These two parts can be completed individually or as sequential activities.)
As students watch the program segment, have them note the materials needed
for building a space elevator, how the space elevator is constructed, and the
components of the prototypes.
Part 1
Help ground students' thinking about the possibility of building a space
elevator. Ask students to review notes they took while watching the program
segment and answer the following questions: Which of these components/materials
would be the most difficult to obtain? Which are readily available? (The
space elevator is a theoretical construct only. The longest carbon
nanotube—the main component of a space elevator—that has been
produced so far is a few centimeters in length. Every other component for a
space elevator is available and in use today.)
Part 2
Have students compare what they learned about the structure of the space
elevator with the prototypes shown in the NASA Space Elevator contest. Using
the notes the students took, develop a list of the components on the board. Ask
students to consider which parts of the contest's prototype models corresponded
to parts of the theoretical space elevator. (A steel cable represented the
proposed carbon nanotube. The prototypes all used climbers with motors very
similar to one that could be used in an actual space elevator. As with the
theoretical space elevator, contestants had to shine lights (instead of a
laser) to illuminate the photovoltaic cells that supplied power to the motors.
The top of the crane represented the satellite in orbit, and the base of the
crane was the platform at sea.)
You may want to have students make drawings of what a space elevator
would look like if it could be constructed. Have them label the satellite in
geosynchronous orbit, the cable that stretches from the satellite to a platform
at sea, the climber with motors that "crawls" along the cable that lifts the
loads, the laser beams that power the motors in the climber, and so on.
Web Sites
NOVA scienceNOW
www.pbs.org/nova/sciencenow/3401/02.html
Offers space elevator related resources, streamed video, and a "Why Build
It" and "Ask the Expert" section.
Carbon Nanotubes
www.personal.rdg.ac.uk/~scsharip/tubes.htm
A concise history and description of carbon nanotube science and technology
and a good list of references.
Space Elevators
science.howstuffworks.com/space-elevator.htm
Provides a simple description of how space elevators will work.
Books
Chemistry
by Ann Newmark and Laurie Buller. Dorling Kindersley, 2005.
Includes information about the chemistry of carbon.
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