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!!