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SPACE ELEVATORS
Space transportation system
Made by:
Akansha vohra
Mechanical engineering
3rd year
Contents
• Introduction
• History
• Importance
• Working
• Components
• Challenges and solution
• Application
• Future
ABOUT THE CONCEPT
• Space elevators are
incredibly tall
theoretical structures
that stretch beyond the
earth’s atmosphere to
transport satellites and
shuttles into outer
space without the cost
and environmental
impact of rocket
fueled launches
PAST OF SPACE ELEVATORS
1960: Artsutanov, a Russian scientist first suggests the concept in a journal
1966-1975: In 1966, Isaacs, Vine, Bradner and Bachus,reinvented the concept, naming it a "Sky-Hook," and published their analysis in the journal Science calculating specifics of what would be required
1979: Authur Clarke, in Fountains of Paradise describes the concept
1999: NASA holds first workshop on space elevators after the discovery of carbon nanotubes.
2001: Bradley Edwards receives NAIC funding for Phase I space elevator mock-up
2005: LiftPort Group announced that it will be building a carbon nanotube
manufacturing plant in Millville, New Jersey,
2011: Google was revealed to be working on plans for a space elevator at its
secretive Google X Lab.
2006 LiftPort Group announced that they had tested a mile of "space-elevator tether"
made of carbon-fiber composite strings and fiberglass tape measuring 5 cm (2 in)
wide and 1 mm (approx. 13 sheets of paper) thick, lifted with balloons
2012: Obayashi Corporation announced that by 2050 it could build a space elevator
using carbon nanotube technology
The Space Elevator in
Science Fiction
Why build it ?
CURRENT
Cost of a launch $10,000 per pound ($22,000 per kg)
Huge vibrations produced and rocket fuel and hardware required
which can’t be reused .
Riding on a continuous and giant explosion is
extraordinarily dangerous, as is re-entry (Challenger, Columbia)
ELEVATOR
Cost of launch $250 per
pound ($660 per kg).
Less vibrations produced and less hardware required and can be used almost every day for space travel.
Safe access to space - no explosive propellants or
dangerous launch or re-entry forces.
How could it be done?
• A space elevator made of
ribbon anchored to an
offshore sea platform
• Ribbon would stretch to a
small counterweight
approximately 62,000
miles (100,000 km) into
space due to rotation of
earth about its own axis
• Mechanical lifters
attached to the ribbon
would then climb the
ribbon, carrying cargo and
humans into space using
different mechanisms.
Main Components
The Ribbon
The Anchors
The Climbers
The Power
Ribbon (tether)
• It is a light, flexible, ultra strong metal that
robots can grip with their climbing treads.
• It act as a guide rail for the climber
• It is a long ribbon of carbon nanotubes that
would be wound into a spool that would be
launched into the orbit.
• When the spacecraft carrying the spool
reaches a certain altitude, perhaps Low Earth
Orbit, it would begin unspooling, lowering the
ribbon back to Earth.
• At the same time, the spool would continue
moving to a higher altitude. When the ribbon
is lowered into Earth's atmosphere, it would
be caught and then lowered and anchored to
a mobile platform in the ocean.
• The cable must be made of a material with a
large tensile strength/density ratio
Why Carbon nanotubes?
• Carbon nanotubes are extremely tiny
rolled-up, three dimensional carbon
tubes, made of a hexagonal graphite
lattice .
• They are at least 1000 times stronger
than steel rods of the same size and
are one-sixth the weight of steel
• They are as flexible as steel.
• The Young’s modulus has been
computed to be on the order of 1.2
Terra Pascal which is 6.25 times that of
steel
• It can be thought as a sheet of graphite
rolled into cylinder.
• They are categorized as single and
multi walled tubes
Growing CNTs
Making Ribbon
Ribbon
Anchor
Anchor station is a
mobile, ocean-going platform
identical to ones used in oil
drilling
Anchor is located in eastern
equatorial pacific
Weather and mobility are primary
factors
Climbers Climbers built with
current satellite
technology
Drive system built
with DC electric
motors
Photovoltaic array
(GaAs or Si) receives
power from Earth
7-ton climbers carry
13-ton payloads
Climbers ascend at
200 km/hr
8 day trip from Earth
to geosynchronous
altitude
Initial 200 climbers
used to build ribbon
Power Beaming Propulsion
• Various methods proposed to get the energy to the climber are:
1. Transfer the energy to the climber through wireless energy
transfer while it is climbing.
2. Transfer the energy to the climber through some material structure
3. Store the energy in the climber before it starts – requires an extremely
high specific energy such as nuclear energy.
4. Solar power – power compared to the weight of panels limits the
speed of climb.
WIRELESS ENERGY SYSTEM INVOLVES:
• The lifter will be powered by a free-electron laser system located on or
near the anchor station
• It requires physical installations at the transmitting and receiving
points, and nothing in between.
• The receiver can be moved to a different location, closer or further
away, without changing the cost of the system
Continued…
• The laser will beam 2.4 megawatts
of energy to photovoltaic
cells, perhaps made of Gallium
Arsenide (GaAs) attached to the
lifter,
• It will then convert that energy
to electricity to be used by
conventional, niobium-magnet
DC electric motors
• In 2009, NASA awarded $900,000
to Laser Motive for their successful
demonstration of "wireless power
transmission" for space elevator
Challenges and solutions
Induced Currents: milliwatts and not a problem
Induced oscillations: 7 hour natural frequency couples poorly with moon and sun, active damping with anchor
Radiation: carbon fiber composites good for 1000 years in Earth orbit (LDEF)
Atomic oxygen: <25 micron Nickel coating between 60 and 800 km (LDEF)
Environmental Impact: Ionosphere discharging not an issue
Malfunctioning climbers: up to 3000 km reel in the cable, above 2600 km send up an empty climber to retrieve the first
Lightning, wind, clouds: avoid through proper anchor location selection
Meteors: ribbon design allows for 200 year probability-based life
LEOs: active avoidance requires movement every 14 hours on average to avoid debris down to 1 cm
Health hazards: under investigation but initial tests indicate minimal problem
Damaged or severed ribbons: collatoral damage is minimal due to mass and distribution
Technical BudgetComponent Cost Estimate (US$)
Launch costs to GEO 1.0B
Ribbon production 400M
Spacecraft 500M
Climbers 370M
Power beaming stations 1.5B
Anchor station 600M
Tracking facility 500M
Other 430M
Contingency (30%) 1.6B
TOTAL ~6.9B
Costs are based on operational systems or detailed engineering studies.
Additional expenses will be incurred on legal and regulatory issues. Total
construction should be around US$10B.
Recommend construction of a second system for redundancy: US$3B
Applications
Solar power satellites - economical, clean power for use on Earth
Solar System Exploration -colonization and full development of the moon, Mars and Earth orbit
Telecommunications - enables extremely high performance systems
Next Steps
• Material development efforts are underway
by private industry
• Space elevator climber competition will
demonstrate basic concept
• Engineering development centers in the
U.S., Spain and Netherlands are under
development
• Technical conferences continuing
• Greater public awareness
• Increased financial support being sought
• Use superconducting property of nanotube
ribbon
• Maglev type ascension
Bibliography
• Spaceref.com
• Howstuffworks.com
• Various science blogs
• Online newsletters and
journals
• Wikiepedia.com
• Spaceghost.com
• Inhabitat.com
• IBTimes.com
QUERIES??
THANK YOU!!