Solar Sails- A future in space

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MINOR PROJECT

SOLAR SAILS


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Solar Radiation PressureSolar radiation pressure is the force exerted by solar

radiation on objects within its reach. It is one of the source oforbital perturbations and is the main source of propulsion for

solar sail.

According to theory of special relativity, photons are massless their

energy (E) and momentum (p) are related by :-

E=p*cThe momentum the photons carry are transferred to the surface.

The disturbance force can be expressed simply as

F = P*S*Cr*R

Radiation pressure is about 105Pa at earths distance

from the sunThe radiation pressure force is inexorable and requires no fuel mass
http://en.wikipedia.org/wiki/Orbital_perturbationhttp://en.wikipedia.org/wiki/Orbital_perturbation


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Radiation Pressure

Waves not only carry energy but also momentum. The effect is very small (we dont

ordinarily feel pressure from light). If light is completely absorbed during an interval

Dt, the momentum transferred is given by

and twice as much if reflected.t

p

F D

D

Newtons law:

Supposing one has a wave that hits a surface of area A (perpendicularly), the amount

of energy transferred to that surface in time Dtwill be

therefore

Radiation

pressure:


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Radiation pressure: examples

Sun radiation: I= 1 KW/m2

Area 1km2 => F=IA/c=3.3 mN

Mass m=10 kg => a=F/m=3.3 10-4

m/s2

When does it reach 10mph=4.4 m/s?

V=at => t=V/a=1.3 104 s=3.7 hrs


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The design of reflector should be large enough to get a

suitable acceleration but of so small a mass to be pushed and

accelerated up to a significant speed by incident photons from

the Sun.

In the above figure I = incident light; R = reflected light; FI =

incident force; FR = reaction force , F = the resultant; S = the

sail

In realistic situation (non perfect reflector) thrust will no

longer be inclined as some incident photons will be

absorbed and subsequently re-radiated as thermal radiation.

Force diagram of

a Solar Sail


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Force agram oa Solar Sail contd.

Due to the absorption temp. of the sail increases

Temp calculated using StefanBoltzmann law

The stresses increase

Tendency to billow increase The final force component is that due to photons which have

been absorbed and then reemitted as thermal radiation from

both the front (reflecting) ck surfaces of the sail.


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sASRP acting on a sail surface

The SRP force acting on a sail surface

with areaA is also often approximated asF PAcos2


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Fluxuations in the radiation pressure

Solar ProminencesProminences are dense clouds

of material suspended above

the surface of the Sun by loops

of magnetic field. Prominences

can remain in a quiet orquiescent state for days or

weeks. However, as the

magnetic loops that support

them slowly change,

prominences can erupt and rise

off of the Sun over the course of

a few minutes or hours


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Solar Flares

Solar flares are tremendous explosions on the surface of the Sun. In a matter of

just a few minutes they heat material to many millions of degrees and release as

much energy as a billion megatons of TNT. They occur near sunspots, usually along

the dividing line (neutral line) between areas of oppositely directed magnetic

fields.


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Material in solar sail:

Solar sails are composed of flat, smooth material covered with areflective coating and supported by lightweight structures attached

to a central hub.

Near-term sails likely will use aluminized Mylar -- a strong, thin

polyester film -- or CP-1, a space-rated insulating material. More robust sails might use a meshwork of interlocking carbon fibers.

The most common material in current designs is aluminized 2 micro

meter kapton film. It resists the heat to pass ,lose the heat to the Sun

and still remains reasonably strong. Research showed that various materials such as alumina for laser

light sails and carbon fiber for microwave pushed light sails were

superior sail materials .


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Booms:

In sailing, a boom is a spar (pole), alongthe foot (bottom) of a fore andaft rigged sail, that greatly improvescontrol of the angle and shape of the sail.

The primary action of the boom is to

keep the foot of the sail flatter when thesail angle is away from the centerline ofthe boat.

Ifbooms alone are to support a solarsail, they must act as columns and asbeams. As columns, the boomsprevent the sail from collapsing

inward towards the center. Asbeams, the booms are stiff and fixedat the center.


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Heliogyros:

The sail consists of several very long (twelve

vanes, seven km in length in the JPL design)

vanes extending from a central hub. Thevehicle continues to spin in order to keep the

vanes tight.

Square:

It is a 3-axis stabilized sail which is square in

shape. one of the most fundamental structural

and mechanical trade is the implementation of

deployable booms.


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ATTITUDE CONTROL

Attitude control is the exercise ofcontrol over the orientation of anobject with respect to an inertialframe of reference or anotherentity (the celestial sphere, certainfields, nearby objects, etc.).

Controlling vehicle attituderequires Sensors - to measure vehicle attitude)

Actuators - to apply the torquesneeded )

Algorithms - to command the

actuators based on (1) sensor measurements of the current

attitude

(2) specification of a desired attitude.


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SUN SENSORS

The sun sensor measures the sunangle with reference to the satellite.

An analog sun sensor is used to pointone of the satellites axes towards thesun as well as for orienting the solarpanels in the direction of the sun inthe geostationary orbit.

A digital sun sensor measures the sunangle with reference to the satellitespitch axis.

The light is passed through severaltransparent and opaque sections ofthe sun sensor reticle. A 0.125

change of the sun angle, a uniquepattern is lighted up and is used as acode to orient the satellite towardsthe sun. INSATs have digital sunsensors.


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THRUSTERS

A micro Plasma Pulsed Thruster (PPT ) is the most suitable for sailsbecause it does not requirepropellant tanks, micromachinedvalves and feed systems.

The PPT, uses solid Teflon as

propellant, electric power toionize and electromagneticallyaccelerates plasma to highexhaust velocities.

The plasma is then accelerated tohigh exhaust velocities by the

Lorentz force. The interaction ofthe current and the self-imposedmagnetic field generates the j BLorentz force.


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VARIABLE REFLECTIVE ELEMENT The liquid crystal device, the variable

reflective element, a thin-filminstrument to change the surfacereflection characteristics of sunlightby turning on and off the power ofthe device.

The devices were enclosed in thinpolyimide film, the same material as

the sail, and mounted in line aroundthe edges of the sail.

As they turn ON and OFF repeatedlyin synchronization with the spin rate,solar-light pressure becomesunbalanced, eventually generatingtorque that affects the entire

spacecraft to tilt its spin axis. Thus attitude of the sail can be

controlled without the use of fuel.


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VARIABLE REFLECTIVE ELEMENT

IMAGES


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SOLAR SAIL DEPLOYMENT


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DEPLOYMENT THE MOST CRITICAL

PHASE Solar Sail mission success depends on how successful

the deployment is .

The sail undergoes dynamic changes from packedstructure to fully deployed stage.

The film is very thin thus

- vulnerable to tear

- vulnerable to shrinks

The spinning system is a solution to these problems .


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STOWAGE The two dimensional folding pattern called rotationally skew

fold


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THE OPTIMUM FOLD

Tests show that :-

larger the radius more faster the deployment

larger the folding pitch lesser is the unfolding

spin rate

spin direction wrapped membrane realizes quick

deployment.

similarity parameter


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The deployment sequence is as follows:1) Separation from rocket with slow spin (5 rpm)

2) Spin down using RCS (5 rpm -> 2 rpm)

3) Release of launch lock

4) Spin up using RCS (2 rpm -> 20 rpm)

5) First stage of the deployment (20 rpm ->

5 rpm)

6) Second stage of the deployment (5 rpm ->

2 rpm)

7) Spin down using RCS (2 rpm -> 1 rpm)

Video simulation of deployment steps of

IKAROS SOLAR SAIL

8) Control of spin direction and rate using steering devices.

The spin rate in both deployment stages is decreased because the moment of inertia of

the sail is increased.

DEPLOYMENT SEQUENCE :-


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DEPLOYMENT MECHANISM
http://en.wikipedia.org/wiki/File:Buran_rear_view_(Le_Bourget_1989).JPEG


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A note on the RCS

(Reaction control system) Purpose is Attitude control and steering by the use

of thrusters.

Use combinations of large and smaller thrusters.

In solar sail it used to spin up the spacecraft, before the

centrifugal deployment and control its attitude throughout

the mission life.

This system stores HFC-134a in liquid-phase in the tank,

extracts the vapor of HFC-134a from the tank, and ejects the

vapour from the thruster nozzle.
http://en.wikipedia.org/wiki/File:Buran_rear_view_(Le_Bourget_1989).JPEGhttp://en.wikipedia.org/wiki/File:Buran_rear_view_(Le_Bourget_1989).JPEGhttp://en.wikipedia.org/wiki/File:Buran_rear_view_(Le_Bourget_1989).JPEGhttp://en.wikipedia.org/wiki/File:Buran_rear_view_(Le_Bourget_1989).JPEGhttp://en.wikipedia.org/wiki/File:Buran_rear_view_(Le_Bourget_1989).JPEG


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Deployment mechanism

Two types of deployment :

Continuous deployment


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Divided Deployment Mechanism


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ZNAMYA EXPERIMENTS

Znamya (Banner) - Main goal was to test large thin film deployable structures as well as

some applications.

to verify the concept of the system,

to test stability

to control the large thin film structure in space.

to run "Novey Svet" (New Light) experiment

Znamya-2:

- Frst practical experiment for the system.

- 20- meter thin film structure was successfully

deployed using centrifugal forces onboard of ProgressM-15 cargo spacecraft.

- Monitored using telemetry and visual devices.

Znamya-2.5

- enlarged size and film tailoring improvements the reflected light

- 5-10 times brighter;

- used to point reflected beam to a few cities after sunset.


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NANOSAIL-D NanoSail-D experiment was developed and

built by NASAs Marshall Space FlightCenter, Huntsville, Ala., in collaboration with

NASAs Ames Research Center, MoffettField, California.

First launch and deployment was in August2008 on a Falcon 1, which experiencedproblems that resulted in the loss of thelaunch vehicle and payloads. But 2 NanoSail-

D flight units were constructed, in case 1failed or another launch opportunity becameavailable.

NanoSail-D, launched in late 2010 andejected 7 days after launch, was one of 6payloads on FASTSAT.

The orbit was to be higher and circular whichmade NanoSail-D more visible to astronomerson the ground and changed the missionduration to 70-120 days.

The sail was made of an ultra-thin reflectivepolymer called CP-1. It was 7.5 microns thick

with a surface area of approx. 100 sq. feetwhen unfurled.


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FEATHERSAILSECOND GENERATION

NANOSAIL CONCEPT

NanoSail-D2 will have the capability to prove

solar propulsion, along with testing the sail

deployment in a zero gravity environment.

This second generation design has been

dubbed FeatherSail due to the extended

functionalities of its sails.

Goal : To leverage recent technological

innovations necessary to meet the needs of

long duration deep space missions.

Dependable sail deployment systems;

Steerable solar sails;

Deployable thin film solar arrays;

Low temperature, radiation tolerant Silicon-

Germanium (SiGe) electronics.


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In their next solar sail project, they intend to pair a solar sail 10 times larger than that of


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IKAROS with the ion engines that took the Hayabusa satellite to asteroid Itokawa and backfor a mission to Jupiter.

They are eyeing a 2019 or 2020 launch so this craft can rendezvous with planned U.S. andEuropean missions and travel to the sphere of Jupiter by combining solar sail technology anda high-performance ion engine.

Objectives:-

To verify navigation technology and demonstrate the solar sail.

Power generation using thin-film solar cells attached on the membrane in addition toacceleration by solar radiation. In the case of a solar power sail, it can gain the necessaryelectric power using a vast area of thin film solar cells on the membrane even when thedemonstrator is away from the sun.

The IKAROS is, therefore, an ambitious mission to verify the above two technologies

together which are essential for us to explore deep space as it would still be possible togenerate sufficient electricity for a mission using a solar array on the sail.


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The success criteria of the IKAROS mission are summarized as follows:-

Deployment of a large membrane sail in space using a similar mechanical device and

procedures to those in a Solar Power Sail craft. It requires housekeeping data that verify the

expansion status of the membrane.

Generation of electricity from the thin-film layer of solar cells on the membrane verified by

housekeeping data.

Demonstration of the photon propulsion technique including verification data of the

reflectance parameters to determine the diffuse and specula properties of the radiation

impinging on the sail. Also, measurement of the overall sail reflectance, the temperature, and

the condition of the sail surface under the influence of debris impacts.

Demonstration of GN&C techniques in support of solar sail propulsion involving navigation

and orbit determination under the conditions of continuous but tiny acceleration. There must

be means to control the acceleration direction and to maintain the attitude of the spacecraft.


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WHICH NASA MISSIONS WILL UTILISE SOLAR SAILS?


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WHICH NASA MISSIONS WILL UTILISE SOLAR SAILS?

Mission name: ST9 (Space Tech 9)

Tentative launch date: 2010-2011 , Estimated sail size: 40 meters on a side

Description: This mission is led by Goddard, in collaboration with JPL and Langley. It will

confirm that the solar sail design and implementation is not only feasible, but durable and

functional. If this mission is successful, engineers believe that scaling the sail size up (from 40 to

100-150 meters on a side) is doable.

Mission name: Solar Sail Demonstration (The Sunjammer Project)

Tentative launch date: 2014 , Estimated sail size: 1200 meters on a side

Description: The project will hold its preliminary design review in 2012 and will launch on a

Falcon 9. At just over 70 pounds, this solar sail demonstrator will weigh 10 times less than thelargest sail ever flown in space. It will produce a maximum thrust of approximately 0.01 Newton. It

is truly propellant less -- it will use control vanes for attitude control.

Mission name: Heliostorm

Tentative launch date: 2016-2020, Estimated sail size: 150 meters on a side

Description: Heliostorm would alert scientists of solar storms that cause problems with Earth-

based communication systems by placing a spacecraft closer to the sun than the current monitoringequipment which could double the warning time before communications problems.

Mission name: SPI (Solar Polar Imager)

Tentative launch date: 2020-2035, Estimated sail size: 150 meters on a side

Description: The SPI mission is one that requires continual thrust and will allow a spacecraft to

orbit the sun at a high angle - giving a good view of the sun's Polar Regions.


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INDIAN PROGRAMME IN SOLAR SAIL

Some extracts from the press released on April 10, 2003 are highlighted as follows:- The Multipupose satellite, INSAT-3A, built by ISRO, was successfully launched early this

morning ( April 10, 2003 ) by the Ariane-5 launch vehicle of Arianespace. INSAT-3Ais thethird satellite in the INSAT-3 series; INSAT-3C were launched by Ariane-5 and Ariane-4launch vehicles on march 22, 2000 and January 24, 2002 respectively.

In the coming days, orbit raising operations of INSAT-3A will be carried out by firing its 440Newton Liquid Apogee motor ( LAM ) in stages till the satellite attains its final geostationaryorbit, which is about 36,000 km above the equator. The satellite has about 1.6 tonne of

propellant ( Mono-Methyl HydrazineMMH fuel and Mixed Oxides of NitrogenMON-3oxidiser) for orbit raising operations as well as for station-keeping and in-orbit attitudecontrol. The on-board availability of propellants will enable maintaining the satellite foroperational period of 12 years.

When the satellite reaches near-geostationary Orbit, deployment of its solar panels as well asits antennas and the solar sail will be carried out and the satellite put in its final 3-axisstabilised mode. This will be followed by trim manoeuvres to take the satellite to its designatedorbital slot. The payloads will be consequently checked out before the commissioning of the

satellite. INSAT-3Ahas its main body in the shape of a cuboid of 2.0 m x1.77x2.0 m. When its solarpanels and solar sails are fully deployed in orbit, the satellite will measure 24.4 m in length.INSAT-3As Sun tracking solar panels generate 3.1 kW of power. Two 70 Ah Nickel-Hydrogenbatteries support full payload operations even during eclipses. INSAT-3A like all itspredecessors in the INSAT series is a 3 axis body-stabilised spacecraft using earth sensor, sunsensor, inertial reference unit, momentum/reaction wheels and magnetic torques. It is equippedwith bi-propellant thrusters. The satellite has two deployable antennas and one fixed antennaethat carry out various transmit and receive functions.


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ALTERNATIVES TO SOLAR SAILS

When the solar sail gets far away from the sun , there is not

enough light available to provide additional propulsion .

Sun is a point source in universe , radiating sunlight in all its

directions in an ever expanding sphere of light . Thus , some other source is required to accelerate the sail

after a distance .


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Laser propulsion is a formof beam-poweredpropulsion where theenergy source is a remotelaser system and separate

from the reaction mass. Advantages :-

Highly directional

Efficiency

Disadvantages :-

Location of laser is aproblem

Divergence

LASER SAILING

PLACING A LASER SAIL IN ORBIT


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On earth Problems :-

Dense atmosphere

Rotation of earth Political problems

In earths orbit Problems :-

Political problems

Tracking and pointing , more difficult now

Generation of power large on board solar arrays required

In suns orbitAdvantages :-

More power can be produced

No atmosphere no added divergence

Pointing easieronly lasers motion to be considered .

Two or three lasers could be used in such a way that one of them is always pointintowards the sail

Problem :-

Divergence

PLACING A LASER SAIL IN ORBIT


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No atmospehric problems

No political problems

Pointing is easier Jupiter orbits the sun in 12 yrs.

Power problem solved by tether . Energy contained in the jovian magnetic field is

harnessed with a long conducting wire or tether . Dueto its motion , a flow of electricity is produced.

So , we can extend the range of solar sails two to fivefolds by putting the laser carefully .

IN THE JUPITERs ORBIT

MICROWAVE SAILING


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Cheaper than lasers

High efficiency.

Microwaves generation has much higher efficiency than laser beams,leading to lower cost of power and reduced waste heat.

Phased arrays.

Microwave phased-arrays are an off-the-shelf technology.

Large apertures.

Large microwave apertures are much easier to fabricate than large laserapertures.

Lightweight mesh sails.

Microwave sails need not be a solid film, but can be perforated as long asthe hole size


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A way of usingmicrowave technology insolar sails is to insert athin film focusing lensinto the microwave beam

between the transmitterand the sailcraft .

But , the problem is thatof another large opticalcomponent that must bepositioned accurately .

MICROWAVE SAILING

PARTICLE BEAM SAIL PROPULSION


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Charged particles ( protons ) are

accelerated to high speeds When they strike a sail , the sail would

move and accelerate

Charged particle beams have one veryserious flaw in their potential applicationto space travel divergence . Thedivergence of a particle beam is caused bythe accelerated particles themselves . As

the beam of charged particles emerges ,protons , begin to push away from eachother until the beam spreads andbecomes too diffuse to be useful .

The first step in producing a neutral beamis making a charged particle beam .Neutral atoms cannot be accelerated in anelectric or magnetic field because they

carry no net charge . Therefore , a beamof charged particles is first produced andaccelerated to high velocities . Passing itthrough a very thin film or plasma cloudthen neutralises the beam

PARTICLE BEAM SAIL PROPULSION

LIMITATIONS OF SOLAR SAILS


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LIMITATIONS OF SOLAR SAILS

Solar sails don't work well, if at all, in low

Earth orbit below about 800 km altitude dueto erosion or air drag. Above that altitude they

give very small accelerations that take months

to build up to useful speeds. Solar sails have to be physically large, and

payload size is often small.

Deploying solar sails is also highly challengingto date.


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APPLICATIONS

Space Science:Help to solve the mysteries of the universe by

use of probes which can enter the fringes of interstellar space

with a short flight time.

Exploration of the solar system:A propulsion system which

will conduct comprehensive exploration of the entire solar

system (including beyond the planets) .

Search for life beyond Earth.

Revolutionize our access to space: Light sails could be a

means to deliver payloads on rendezvous missions to the

outer planets.


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THANK YOU

NAME ROLL NO.

ABID NABI KHANDEY 1

ANJANA KUMARI 2

MANISH TRIPATHI 16

MUSHFIQ SARFARAZ 17

SADHANA SINGH 22TEJASVI THANAI 30

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Solar Sails- A future in space