The Space Elevator

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TheSpaceElevator

• A Space Odyssey

Ben Shelef ben_at_spaceward.org http//www.space
ward.org
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2009 Games at NASA Dryden
Official Trailer
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TheSpaceElevator

• A Space Odyssey

Ben Shelef ben_at_spaceward.org
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1960 ? ? ?
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The Early Days
USA First Satellite 1958 Man in Orbit 1962
USSR First Satellite 1957 Man in Orbit 1961
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Space Fever
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Yuri Artsutanov
To the Cosmosby Electric Train
Tsiolkovskysrocket equation
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The trouble with rockets
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Drop a cable from a satellite
Counter-weight
24 hrs.
Very long cable
Too slow (30 days) 240,000 miles
Just right (GEO) 25,000 miles
Too low (LEO) 150-500 miles overhead 90 minutes
24 hrs.
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Swing a ball on a string
1 foot string ? 1.1 seconds (or less) to go
around
1500 foot string ? 42 seconds (or less) to go
around
86,400 seconds (one day) to go around ? String
needs to be at least 25,000 miles long
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The 25,000 mile problem
How long can a cable be before it breaks under
its own weight?
Steel wire get usabout 50 miles
Advanced Kevlar and similar materials get us a
bit more than 250 miles
Until recently, no known material even come close
to what we need for a Space Elevator
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The power problem

• During the beginning of the trip, 20 ton climber
  ascending at 50 m/s is drawing 10 MWatt of power.
• How do we power a climber?
• Will the mass of the power system exceed the mass
  of the climber?
• Where do we store the energy?

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??? 1990 .
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Carbon Nanotubes

• New class of molecules tubes of carbon atoms
• Discovered in 1991 by Sumio Iijima
• Individual nanotubes are 30 times stronger than
  steel and 6 times lighter
• A tether made out of Carbon Nanotubes will
  bestrong enough to construct the Space Elevator !

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Photonics

• New breed of electrical lasers featuring
  acceptable efficiencies, wavelengths, and
  lifetimes.
• Multi-MWatt systems are feasible.
• New breed of very light thin-film PV cells.
• Power densities of several kWatt/kg are feasible.
• With power beaming, leave the power system!
• Safe, Reliable, Low Cost.

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The Modern Space Elevator

• A space launch system that can carry tons per
  day, to any destination in the Solar System, at
  extremely low costs.
• No smoke, no fire safe and environmentally
  friendly.
• No stress travel at a leisurely 120 mph,
  transition gently from 1g to 0g.
• Infinitely scalable there is no limit onhow
  large (or small)a Space Elevatorcan be.

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or travel to the end of the ribbon and get
slung to an Earth escape trajectory no extra
fuel necessary!
Step off into orbit at GEO

• Destinations
• LEO, GEO
• Moon, Mars
• Venus, Asteroids

24 hrs.
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Our Sponsors
Thank you!
(Your Company Name Here)
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Movie Time v.1
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Movie Time v.2
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The Bad News

• First estimates placed CNTs at 100 N/Tex
• Recent estimates are in the 40 50 N/Tex range
• How strong does the tether really have to be?
• Is this a show-stopper?

(Stone-Wales Defect Formation)
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The Good News

• 400 m2 total area
• 32 kg including structure and deployment
  mechanism (at center)
• 50 kWatt (lt10 efficient)
• 1.5 kWatt/kg today, potential for 3-5 kWatt/kg

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Eat Your Cake and Have it Too !

• If the tether is weaker/heavier than expected
• The taper ratio will increase
• The ratio of tether mass to payload capacity
  (TMR) will increase
• Not fatal railroads are always heavier than the
  trains!
• If the power system is weaker/heavier than
  expected
• Well move slower
• Well carry less payload
• Our Payload Mass Throughput (PMT) is reduced
• Still much better than rockets!
• Really?

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The Space Elevator Feasibility Condition

• Tether lifetime (TL)
• Every material degrades UV, Micrometeorites
• Entire tether must be replaced every TL years
• Time-to-Double (TD)
• We cam only launch (by rockets) fraction-sized
  Space Elevators
• Orbital spares are fraction size (FS)
• Characteristic Time Constant
• The time it takes the Space Elevator to lift its
  own weight

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The Space Elevator Feasibility Condition

• Assuming, TD 1.5 years, FS 25, TL 6 years
• ? CTC 1 yr.
• Impossible lt Space Elevators lt Easy

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So Back to the Games!

• July 14, NASA Dryden Flight Research Center,
  Mojave, CA
• 6 teams, up to 2,000,000 in prize purse
• Looking for additional sponsorships!

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Our Sponsors
Thank you!
(Your Company Name Here)
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Contact

• http//www.elevator2010.org
• http//www.spaceward.org
• ben_at_spaceward.org
• 650-793-4987
• 725 N Shoreline Blvd.
• Mountain View, CA 94043

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FIN