1. The Elevator to Heaven, the Stairway to Space Daniel Burton Josh Denholtz Sergey Galkin

2. Topics of Discussion  Introduction to the Space Elevator  Original Designs  Parts of Elevator - Ribbon - Motor and Rollers - Platform - Power o Construction of Elevator / Final Design o Future Plans

3. The Space Elevator  First in depth study came in 1950s by Dr. John McCarthy  Described a synchronous Earth skyhook going up to a space station in geosynch orbit  Materials not yet available to build elevator www.beyondsciencepodcast.com

4. New Materials Become Available  Graphite whiskers become available in 1957  Tensile strength of 210,000 kg/cm^2 compared to the next best material (fine grade drawn steel wire) with a strength of 42,000 kg/cm^2  20 times better than steel (strength and density considerations)

5. Carbon Nanotubes  First invented in 1991  Has a density of 1.3 g/cm^3 (close to half that of graphite whiskers)  Tensile strength is 1,327,000 kg/cm^3  Self support up to 10,204 km (compared to 1,050 km for the graphite whiskers)  No other known molecular bonds stronger than this arrangement  22 tons of nanotubes compared to 700,000 tons of graphite whiskers would be used  Definitely the material to use www.ewels.info

6. Getting Started  Original startup involves the transportation of a rocket containing the parts necessary to build a spaceship (counterweight) in orbit  Spaceship will assemble in orbit and launch a smaller ship to anchor the carbon nanotube ribbon to the Earth (most likely on a sea based platform)  Climbers will travel up to the orbiting spaceship splicing together the ribbon and making it stronger

7. The Ribbon  Ribbon will be made of nylon  Ribbon will be 15’ in length (will be dropped from the Mezzanine), 6” in width, and.031” in thickness  Strong material and able to withstand forces that will be put on it  Cost efficient means of simulating carbon nanotubes

8. Platform  Platform will be made of aluminum  Will be circular in cross section with a radius of 1’ and a thickness of 0.25”  Will have a cutout with dimensions 9” by 1” (necessary for the ribbon to pass through)  Solar panel will be mounted on the bottom of the platform to avoid center of mass and space issues  Gear box used to house rollers will be made of the same material

9. Construction of the Elevator  Motors  Rollers Large Cylinders Small Cylinders Rods

10. First Design  Mechanism  Static Performance Friction Center of Mass

11. First Design Gear Shaft Torque Rotational Speed Axle

12. Second Design  Mechanism  Static Performance Friction Center of Mass

13. Second Design  Moving Parts Together Chain Miter Gear

14. Final Design  Mechanism  Gear Shaft Torque Rotational Speed  Moving Parts Together Chain Miter Gear

15. Final Design  Static Analysis Purpose Quasi-static

16. Final Design  Tension Initial Tension Tension Formula and Constraints

17. Final Design  Friction  Results F net =14.8cos45+11. 8+8.65+6.3+4.6+ 3.6cos45=41 41<80 

18. Final Design (It’s not done yet)  Other Friction Factors Coefficient of Friction Resultant Force Small Cylinders Rollers

19. Power Photovoltaic Cells  Photovoltaic Array on bottom of climber  Required power output unknown  Required price unknown www.isr.us

20. Estimated Power and Cost Calculations  Assume 1000 watts necessary output.  Assume solar panels have 20% efficiency.  Assume 6cm diameter cell generates 0.5 volts and 0.5 amperes of output.  Required input = 1000/(20/100) = 5000 watts.  Total output generated per photovoltaic cell = 0.5 Volts*0.5 amperes = 0.25 watts.  Total # of cells = 1000 watts output/ 0.25 watts per cell = 4000 cells.

21.  Area of 1 cell = 3*3*π = 9π sq. cm.  Total Area = 4000 cells * 9π sq. cm. per cell = 36,000π sq. cm.  Radius of Base = √(36,000π/π) = 189.737 cm = 1.90 m Calculations (Continued)

22.  If we were to use flexible solar panels from McMaster-Carr (part # 4859T11): Assume generate 9.2 watts electrical output. Total cell area = 437 sq. in.  To obtain 1000 watts of electrical output: 1000 watts/9.2 watts per cell = 109 cells Total area = 109 cells*437 sq. in. per cell = 47,633 sq. in. Base radius = √(47,633/π) = 123.124 in. = 3.127 m  Price per cell = $232.00 www.mcmaster.com Solar Panel

23. Ways to Reduce Power Requirements  Use the solar panels to charge a set of capacitors, from which the motors would run.  Use high revolutions-per-minute motors that require less power to operate Would use a series of gears to increase the torque.

24. Power Supply  For the power-beaming test, there are two possibilities: Manufacture a concentrated light beam emitter using a 1000-watt bulb and a parabolic mirror. Rent a projector from a supplier  Approximate cost to rent a projector = $150.00 http://library.thinkquest.org

25. Future Plans  Complete Design and Budget Proposal  Prototype Construction Climbing mechanism complete by end of Fall semester. Power-beaming mechanism complete by end of Spring 2007 semester.  Final Assembly and Testing at the end of Spring 2007. Testing will occur at the Rutgers Department of Mechanical Engineering Mezzanine.

26. Review of Original Goals  Construct and Test gear-based climbing mechanism.  Use Type III parachute cord for ribbon manufacture.

27. Modifications of Original Goals  Manufacture of ribbon from Type III parachute cord proved too time consuming Decided to use pre- manufactured nylon ribbon  Motor costs exceeded total budget. www.mcmaster.com

28.  Project deadline extended to end of Spring 2007  Design modifications: Uses a roller system instead of a gear system  Rollers manufactured to provide maximum friction  Design additions: Addition of a power-beaming test concept  Ribbon modifications: Increased thickness, shortened length Changes

29. Parts List and Budget (Major Parts) PartPart #QuantityPriceTotal Price Aluminum8973K451166.14 Rollers85035K21227.0454.08 Smaller Rollers 84975211101.0710.70 Smaller PartsN/A 50 (estimated) 50 Ribbon8730K2615 ft1.53 per foot22.95 Metal Wire8904K7518.91 Total Estimated Budget (Not Including Motor and Power) = $336.03

30. References  Edwards, B., & Westling, E. (2003). The Space Elevator: A Revolutionary Earth-to-Space Transportation System. Houston, BC Edwards.

31. Special Thanks  Prof. Haym Benaroya  John Petrowski  Yuriy Gulak  Elan Borenstein