space elevator.ppt

8/14/2019 Space elevator.ppt

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SUBMITTED BY:-PARAS JOSHIR180207035

Space Elevator


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Introduction

A Space Elevator is a proposed space launch structure without theuse of rockets which can be used to transport material fromearths surface into space. It is essentially a long cable extending from our planet's surfaceinto space with its centre of mass at geostationary Earth orbit(GEO), 35,786 km in altitude.It is basically the concept of Konstantin Tsiolkovsky, consideredto be the founding father of rocketry and astronautics.

The centrifugal force of earth's rotation is the main principle behind the elevator.


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Introduction Cont.

The concept most often refers to a cablethat reaches from the surface of theEarthon or near the Equator to geostationaryorbit (GSO) and a counter-mass outside

of the atmosphere .This structure would be held in tension

between Earth and the counterweight inspace like a guitar string held taut .


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Mathematical background

While considering Space elevator apparent gravitationalfield comes into play which is given by-

g= -K.M/r+w.r Whereas near the earths surface, itll be given as -

g=K.M/r Where g=acceleration along radius

K=gravitational constant

M=mass of the earthr=distance from that point to earths center


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Math. Background Cont.

The main technical problem is the long cable's own weight. It can be strong enough to hold 35,000 km of itself.The solution is to build it in such a way that at any given point,its cross section area is proportional to the force it has towithstand and as per given formula-

g= acceleration along the radius S =cross-area of the cable at any given point r

dS=its variation =density of the material used for the cable

=traction a given area can bear without splitting


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Counter Weight

The emphasis is given to the counter weight as it is the mainsupport to hold the elevator and the climber.

Some of the proposals are :-A heavy asteroidA space station, space dock or space port beyond geostationaryorbitAn extension of the cable itself far beyond geostationary orbit.

The third proposal is considered to be the better one due to itssimplicity and the fact that payload may slip into theinterplanetary space because of gained velocity when reachedthe extreme end of the cable .


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Material Used

Carbon nanotubes would be the bestoption for the purpose as it is thestrongest and stiffest material yetdiscovered in terms of tensile strength

and elastic modulus respectively.Carbon nanotubes are allotropes ofcarbonwith a cylindrical nanostructure.

Nanotubes have been constructed withlength-to-diameter ratio of up to132,000,000:1 .


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Tether Technology

A tether is a cord or fixture that anchorssomething movable to a reference pointwhich may be fixed or moving .

In tether technology, cables, miles long,are stationed in an orbit around the earth.On one end there is a shuttle and on theother end of the tether would be a counter

mass.This system picks up spacecraft in loworbits and hurls them into higher orbits ortowards other planets .


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Power Beam Technology

It is an electromagnetic radiation through a process of opticalamplification based on the stimulated emission of photons.Power Beam is revolutionizing the mode of power transmission

by integrating optical technology to produce safe, reliable andabundant wireless power.Power Beam operates at a wave length which is 1400nm orgreater. These waves create the beam. The beam is collimatedgiving us the ability to achieve great distances without loss in

power or efficiency.


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Risks Involved

Some of the risks which need to be considered are:-All satellites with perigees below the top of the elevator wouldeventually collide with the elevator cable .Meteoroids present another problem, they would not be

predictable and much less time would be available to detect andtrack them as they approach Earth.Corrosion is thought by some to be a risk to any thinly builttether.Material defect would be one of the causes as because largestructures have more defects than small structures


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Conclusion

Space Elevator is best option to transport material into the spaceas it uses a fraction of current cost.As of 2000, conventional rocket designs cost about $11,000 per

pound ($25,000 per kilogram) for transfer to geostationary orbit.Current proposals envision payload prices starting as low as $100

per pound ($220 per kilogram).As we are planning to explore the universe therefore it can be a

better option to use this approach so as to be economical and time

efficient.


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THANK YOU

space elevator.ppt

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