The Space Elevator

 “Every industrial process we’ve got we’re going to throw out the window” (Flight, 2006)

Since the discovery of nanotubes in 1991, speculations from experimental and theoretical studies of their electronic, chemical and mechanical properties have placed them, as well as their graphene counterpart, in the limelight of the rapidly growing field of nanoscience and technology.  Research indicates that carbon nanotubes are perhaps 100 times stronger than steelat a fraction of the weight, and are flexible to boot.

Despite their extreme strength, carbon nanotubes have an extraordinary length to diameter ratio (aspect ratio).  If the diameter of a typical carbon nanaotube (1 nm) was scaled up to let’s say the diameter of a human hair (100 μm), for example, it would be in the range of 100 m long!

Carbon nanotube materials are among those expected by some to revolutionize materials science as we know it.  One exciting hypothetical application being pursued for carbon nanotubes is in the design of the space elevator, as essential structural component of which could be a carbon nanotube composite ribbon.  While just a few centimeters wide and nearly as thin as a piece of paper, the ribbon will support mechanical lifters that will carry cargo and humans into space and back.

Take Me to the Top, Bucky! is an investigation that focuses on the mechanical properties of buckytubes (carbon nanotubes) such that might be utilized in projects like the space elevator.  Students begin with an introduction to why a space elevator would be beneficial to space exploration and possible colonization.  They brainstorm in groups to create and draw a prototype of a design of a composite ribbon.

 
 

The composite uses a fiber to model the use of nanotubes as a was to strengthen a material.  Following the designof their prototype, students then construct, and test a composite ribbon, modeling one possible application of the carbon nanotubes.

 




 

Once student teams have constructed their comosite ribbon, they conduct a quantitative test of tensile strength to compare the degree of stretch verus the non-composite counterpart.  Measuring force versus change in length, students graphically plot their results, including the force at which the ribbon(s) fail.

The idea of an elevator to a station in geosynchronous orbit around the Earth is an engaging topic for students.  Inquiry investigations like The Space Elevator enable teachers to introduce elements of nanosciene and the modeling of nanoscale materials in traditional science, mathematics and engineering curricula in authentic and meaningful ways.

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References:

I authored this lesson as part of the instructional materials for the NCLT (National Center for Learning and Teaching Nanoscale Science and Engineering) teacher professional development and outreach programs.