Seminar PPT on the topic Space Elevator with details on the Journals used for study. Content: >Concept >Why built it >Component study >Major hurdles >Bibliography Space elevators are incredibly tall theoretical structures that connects the earths surface and outer space, beyond the geosynchronous orbit (35,800 km). The structure acts as a continuous and viable channel by which payload can be send in to space.

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THE SPACE ELEVATOR
Noyal Sharook
M7B
37
Guided By
Padmakumar P
Mechanical Department

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Contents
• Concept
• Why built it
• Component study
• Major hurdles
• Bibliography

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ABOUT THE CONCEPT
Space elevators are
incredibly tall theoretical
structures that connects
the earths surface and
outer space, beyond the
geosynchronous orbit
(35,800 km). The structure
acts as a continuous and
viable channel by which
payload can be send in to
space.

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Why build it ?
CURRENT
Cost of a launch $22,000 per kg
Huge vibration, more hardware and
non reusability
Riding on a continuous and giant
explosion is extraordinarily
dangerous, as is re-entry
(Challenger, Columbia)
ELEVATOR
Cost of launch $660 per kg.
Less vibrations , less hardware required
and continuous use
Safe access to space - no explosive
propellants or dangerous launch or
re-entry forces.

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The Components
 The Cable
 The Anchors
 The Climbers
 The Power

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Cable
• The cable acts as a guide rail for
climbers and should be strong,
flexible and light
• Considering all these factors along
with meteor impact effect, a
ribbon-type epoxy/nanotube
composite design is optimal
• The ribbon is made such that its
thickness is more near the
geosynchronous orbit (5cm)
thanat its ends (11.5cm)( tapered
construction)

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Why Carbon Nanotubes?
Property Single Walled
Nanotubes
Metal wires
Tensile Strength 130 GPa Steel < 5GPa
Kevlar 3.6 GPa
Resilience Can be bent at large
angles and
restraightened
without damage
Metals and carbon
fibers fracture at
grain boundaries
Temperature stability Stable upto 2800
degrees in vacuum,
750 degrees in air
Metal wire in
microchips melt at
600 to 1000 degrees
C
Density 1300 kg/m^3 Steel 7900 kg/m^3
Kevlar 1440 kg/m^3

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Cable Deployment
• Initially a small, stable cable (1 lakh km) is spooled up in a
space craft and send in to the geosynchronous orbit.
• The cable is connected to spindle on either side, which will be
deployed to opposite sides on reaching orbit.
• One end will fall on to earth due to gravity while the other will
be pulled outward due to centripetal acceleration
• Once the cable is anchored on earth, it is built on and made
larger using climbers.

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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

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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
 Initial climbers are used to build ribbon
and are sent up at every 0.1g (13,000km)
altitude
 1 week to reach geosynchronous orbit ,
utilizing 80w/kg

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Power Beaming Propulsion
• Various methods proposed to get the
energy to the climber are:
1. Wireless energy transfer
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.

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WIRELESS ENERGY SYSTEM
• 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
• 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

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Major Hurdles
• Ribbon Construction
• Atmospheric:
oLightning
oHigh Winds
oAtomic Oxygen
• Orbital:
oMeteors
oLow orbit object
oRadiation damage
• Ribbon Breakage

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Sufficient Ribbons
Problems:
• Nanotubes must be
defect free and straight
• The epoxy must be
strong yet flexible, burn
up at a several hundred
Kelvin, and cure
relatively quickly
• Large scale behavior of
nanotubes unknown
Solutions:
• Nanotubes are grown
aligned, and defects can
be controlled in current
production methods,
(spark gap)
• The ribbon can be
produced in small
length bundles and then
connected

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Atmospheric Oxygen 60-100km
Threat:
• Extremely corrosive, will
etch ribbon epoxy and
possibly nanotubes
Solution:
• Coat ribbon with Gold or Aluminum
which have resisted etching in these
atmospheric conditions,(NASA’s Long
Duration Exposure Facility

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Low Orbit Objects and Micrometeors
Threat:
• 108,000 (>1cm)
objects with enough
velocity to sever or
critically damage
tether. Strikes could
occur ~every 14
hours
• Micrometeors <1cm
and > 2cm involved.
Solution:
• Tracking systems for
objects >10cm
already in place, sea
platform will move
tether to avoid
• Tracking systems for
1-10cm objects
coming on-line

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Lightning
Threat:
• Ribbon has lower
resistivity than
surrounding air, lighting
will prefer this path.
Solutions:
• Platform lies in a region
of very low lightning
activity
• Platform is mobile, and
can move tether out of
the way of incoming
storms

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High Winds
Threat:
• 32m/s wind velocity
will induce enough
drag to destroy tether
Solution:
• Winds at platform
location consistently
below critical velocity
• Width of tether will
be adjusted to
minimize wind loading

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Bibliography
• DESIGN AND DEPLOYMENT OF A SPACE ELEVATOR Bradley C.
Edwards Los Alamos National Laboratory, Mail Stop D436, Los
Alamos, NM 87544, USA
• The space elevator: a new tool for space studies Edwards BC
Eureka Scientific, Seattle, WA, USA.
brad_edwards@yahoo.com
• Getting to Space on a Thread .. Space Elevator as Alternative
Access to SpaceJason R. Kent, Major, USAF, PE
• https://en.wikipedia.org/wiki/Space_elevator
• http://spaceref.com/space-elevator/

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QUERIES??

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THANK YOU!!