SOLAR SAIL

SOLAR SAILGeethika MuralidharanB10 ISPCUSATContentsIntroductionHistoryWorkingComponentsSail designsMissionsApplicationsMerits and demeritsconclusion

IntroductionSolar sail is a space craft without engine. It is pushed along directly by light particles from the sun, reflecting off giant mirror like sails. Because it carries no fuel and keeps accelerating over almost unlimited distances, it is the only technology now in existenceIntroduction400 years back Johannes Kepler proposed the ideaIn the 1960s, James Clerk Maxwell predicted that electromagnetic radiation exerts a pressure because of the momentum property of radiation

Sails: using sunlightSail pointed at sun, experiences force Sun pushes the sail directly away Reflected light generates reaction force much like reaction force of rocket

Sailboats: Using windBernoullis principle:Drag when wind moving over the sails (small neglect)Wind flows over airfoil sail receives force perpendicular to wind directionBoat moves forward

Sails: using sunlightLight is made up of packets of energy known as photonsIncident rays of sunlight reflect off the solar sail at an angleChange in momentum pushes the sail

Working Two components of forceIn the direction of incident sunlight In the direction normal to the incident raysComponent tangent to the sail surface cancel outComponents normal to the surface add up to produce the thrust normal to the sail surface

Why solar sails ?Solar sail is effectiveNo noticeable frictionSpace is very empty and clean so there is plenty of roomContinuous supply of energy

Distance v/s time

Comparative studyIn 100 days, a sail-propelled craft could reach 14000 kilometers per hourIn just three years a solar sail could reach over 150000 miles per hour At that speed you could reach Pluto in less than five yearsFar away from the sun, the highly focused beams of lasers can be directed at the sails to boost them onto interstellar trajectoriesComponentsContinuous force exerted by sunlightA large, ultra thin mirrorA separate launch vehicleUltra thin mirror :-large flat smooth sheets of very thin film, supported by ultra light weight structuresSide of film which faces the sun is coated with highly reflective materialSometimes reinforcement are also providedSail parametersSail loading ()(mass/area)Acceleration8.25/ in mm/s2Lightness number=ac/5.93

Sail designsSquare sailLarge, flat reflective film4 spars from hub

Optimum DesignPacking/deployment issuesNo spin to maintain tension

Helio gyro

Plastic-film blades deployed from rollers Film held out by centrifugal forces No mass advantage over a square sailAttractive because the method of deploying the sail is simpler than a square sailSpinning disk sailsPanels are attached to the edge of a rotating spacecraftHave slight gaps, about 1%-5%of the total areaLines would connect the edges of sailsWeights in the middle of these lines would pull the sails tautSail deployment

Essential qualitiesLightweightHighly reflexiveTolerate extreme temperaturesMaterialsAluminiumTitaniumNickelSilicon monoxideboronMissions Cosmos1

Eight triangular sailsMylar thin polyester 30 m wideInsert 825 kilometer near polar orbitMylar suffer high temperature+radiation Worlds first solar sailLaunch planned June 21st 2005Solar sail lost due to booster failure

Missions: Nanosail -DNano satellite or CubesatDesigned to test he potential for solar sails in atmospheric brakingUsed an ultra- thin and light polymer named CP1Deployed in low earth orbit, about 650kmLaunched by falcon -1 launch vehicle in august 2008

JAXA/ISASJapan pursuing solar power sailsSolar sail gathers sunlight as propulsion by means of a large membraneSolar power sail- obtains electricity from thin solar cells on the membrane+acceleration by sunIon propulsion engines accelerate ions driven by solar cells:-hybrid engineAugust 10 2004Deployed on S-310 rocket, first successful one

IKROS (May 20, 2010)

Hybrid solar sail propelled partly by solar pressure, partly by traditional solar pressureH-IIA rocket14X14 m solar sail 307 kgSeparate from rocket spin to unfurl sail Six month mission IKROS headed towards VenusSolar sail powered craft continue even fartherFuture solar sailingHelio storm(2016-2020)150x150mSolar polar imager(2020-2035)150x150mInterstellar probe(2031) 250x250m

ApplicationsSolar weather stationsMonitoring the geomagnetic stormsLaunching small satellitesRemote sensingProbes to the end of milky waySearch for extra terrestrial life

Merits and demeritsMeritsLonger distance can be coveredRequires no fuelFaster than chemical rocketDemeritsDont work well in low earth orbit below about 800km altitude due to erosion or air dragSails have to be physically largePayload size is often smallDifficult to carry manned missions

Solar sail technology is crucial for the next generation of space travelReferenceswww.howstuffworks.comwww.nasa.orgwww.planetarysociety.orgwww.wikipedia.org