1Sept. 15, 2006Exploratorium The Space Elevator: An Exciting Challenge Tom Nugent Research Director LiftPort, Inc.

2Sept. 15, 2006Exploratorium Think Big!

3Sept. 15, 2006Exploratorium A Space Elevator? Railroad to space Port of the Solar System

4Sept. 15, 2006Exploratorium How Does It Work? Just like twirling a ball-on-a-string over your head Balance forces above and below GEO Taper ribbon cross-sectional area for constant stress Net tension in ribbon allows vehicles ( “ Lifters ” ) to climb into orbit

5Sept. 15, 2006Exploratorium The Liftport

6Sept. 15, 2006Exploratorium Ribbon+Lifter

7Sept. 15, 2006Exploratorium Counterweight

8Sept. 15, 2006Exploratorium Deployment Seed ribbon –~1 tonne capacity Assemble in LEO, boost to GEO via power beaming Lower one end of ribbon towards Earth, boost other end Gravity-gradient stabilization

9Sept. 15, 2006Exploratorium Why Build It? (1) Safety & Reliability – Rockets have ~5% failure rate – SE gives a gentle ride Reduced vibrations etc. for cargo

10Sept. 15, 2006Exploratorium Why Build It? (2) Economics – Rockets are Expensive – Ferries vs. Bridge, or Covered Wagon vs. Railroad Capacity – SPS? – Bigger satellites – Real estate (GEO port) Profit!

11Sept. 15, 2006Exploratorium Why Now? Carbon nanotubes (discovered 1991) make the SE feasible –High strength –Low density

12Sept. 15, 2006Exploratorium Strength-to-weight is most important property Requires improvement of 11x-25x! –Get mass reduction by factor of trillions –What is appropriate safety factor? Strength!

13Sept. 15, 2006Exploratorium Research Questions (1) Lightning Wind Twist of ribbon Weight of precipitation Atomic oxygen Orbital Debris Deployment Power Beaming

14Sept. 15, 2006Exploratorium Research Questions (2) Elastic energy –Cascading failure? Ribbon safety factor –Learn from structural engineers, current systems

15Sept. 15, 2006Exploratorium Research Questions (3) Thermal flux – Earth's shadow – CTE mismatch between CNTs and matrix Electromagnetic interaction

16Sept. 15, 2006Exploratorium Research Questions (4) Lifter vehicle –Endurance –Multiple physical regimes –Heat management Others: –Radiation damage to ribbon –Ribbon inspection and position monitoring –Adequate testing of pre-cursor components –Cumulative damage –Vehicle acceleration limits –Alternate designs (e.g., balloon platform)

17Sept. 15, 2006Exploratorium Roadmap

18Sept. 15, 2006Exploratorium How Do We Tackle Questions? Piggyback on research in other fields – Space tethers, laser launch, debris mitigation, weather forecasting, magnetosphere, material fatigue, etc. “Volunteers” – Most current SE researchers Partner with interested researchers – Collaborate on grant-writing Pay big $$ for detailed engineering work

19Sept. 15, 2006Exploratorium Finding Solutions Partnering –Universities: professors, graduate students, undergrads, research staff Guidance –Thesis topics –Independent study projects –Volunteers Interns and LiftPort in- house work Let ’ s talk! and more!

20Sept. 15, 2006Exploratorium Want More? To Learn More and Get Involved: – Sign up for our Newsletter – Newsletter box at – Join our Forums – – Buy our new book! – Tell your friends and colleagues