CubeSat Design for Solar CubeSat Design for Solar Sail Testing PlatformSail Testing Platform

Phillip HempelPhillip Hempel Paul MearsPaul Mears

Daniel ParcherDaniel Parcher Taffy TingleyTaffy Tingley

December 5, 2001The University of Texas at Austin

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Presentation OutlinePresentation Outline

Introduction

Propulsion

Tracking

ElectronicsStructure &Deployment

OrbitalSimulation

BudgetConclusion

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Project GoalProject Goal Design a Test Platform for Solar Sail Design a Test Platform for Solar Sail

Propulsion TechnologyPropulsion Technology• Measure thrustMeasure thrust• Measure solar sail efficiencyMeasure solar sail efficiency• Model satellite orbitModel satellite orbit

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ConstraintsConstraints CubeSat Prescribed ConstraintsCubeSat Prescribed Constraints

• 10cm sided cube10cm sided cube• 1 Kg weight1 Kg weight• Timing system to delay power-onTiming system to delay power-on• Space-flown or approved materialsSpace-flown or approved materials

Adopted ConstraintsAdopted Constraints (for simplicity and reliability) (for simplicity and reliability)

• No attitude controlNo attitude control• No powered systems No powered systems (except required timer)(except required timer)

• No communications systemsNo communications systems

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Laser RangingLaser Ranging Information needed for thrust analysisInformation needed for thrust analysis

• Orbital position for a significant portion of the Orbital position for a significant portion of the satellite’s orbitsatellite’s orbit

• Rotation rates and angles over that timeRotation rates and angles over that time

- A corner cube reflector (CCR) consists of three - A corner cube reflector (CCR) consists of three orthogonal mirrors that reflect light back to orthogonal mirrors that reflect light back to sourcesource

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Laser RangingLaser Ranging McDonald Observatory McDonald Observatory

Laser Ranging (MLRS)Laser Ranging (MLRS)• Satellite visibility sufficientSatellite visibility sufficient• Can provide position to Can provide position to

within 1 centimeterwithin 1 centimeter

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Laser Ranging SpecificsLaser Ranging Specifics Four CCR’s will define sail planeFour CCR’s will define sail plane

• Defines position and attitudeDefines position and attitude• Double sided glass arrays with 3mm corner Double sided glass arrays with 3mm corner

cubes (custom design)cubes (custom design) Design impactDesign impact

• Volume and weightVolume and weight• Laser pulse force = 9.5e-26 NLaser pulse force = 9.5e-26 N

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ElectronicsElectronics Rocket Data Acquisition SystemRocket Data Acquisition System

• Input - 10.7 V at 9-10 mAInput - 10.7 V at 9-10 mA• Output- time coordinated voltagesOutput- time coordinated voltages

Three UltraLife Lithium Ion Three UltraLife Lithium Ion Polymer BatteriesPolymer Batteries• Output- 3.8V for 530 mAhOutput- 3.8V for 530 mAh

Thermal AnalysisThermal Analysis

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Presentation OutlinePresentation Outline

Introduction

Propulsion

Tracking

ElectronicsStructure &Deployment

OrbitalSimulation

BudgetConclusion

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Mechanical SystemsMechanical SystemsPhillip HempelPhillip Hempel

Structural DesignStructural Designandand

Solar Sail DeploymentSolar Sail Deployment

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Satellite ComponentsSatellite Components Frame/ Corner Cube ReflectorsFrame/ Corner Cube Reflectors Satellite ComponentsSatellite Components

• Kill SwitchKill Switch• TimerTimer• SailSail• CapillariesCapillaries• Inflation CapsuleInflation Capsule• Hardening StripsHardening Strips

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Mechanical OverviewMechanical Overview Satellite ComponentsSatellite Components Weight and Volume BudgetsWeight and Volume Budgets Component PlacementComponent Placement Solar Sail Deployment / ModelSolar Sail Deployment / Model

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Satellite AssemblySatellite Assembly

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Sequence of EventsSequence of Events CubeSat Released / Deactivate Kill CubeSat Released / Deactivate Kill

SwitchSwitch Timer Waiting PeriodTimer Waiting Period Unlock Side PanelsUnlock Side Panels Begin InflationBegin Inflation Inflation Ends / Rigidization OccursInflation Ends / Rigidization Occurs Final shapeFinal shape

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PropulsionPropulsionTaffy TingleyTaffy Tingley

Solar Sail Design Solar Sail Design and and

Finite Element SimulationFinite Element Simulation

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Solar Sail DescriptionSolar Sail Description

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Solar Sail MaterialSolar Sail Material

Aluminized MylarAluminized Mylar

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Solar Sail ConfigurationSolar Sail Configuration

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Finite Element Model Finite Element Model ConfigurationConfiguration

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FE Test #1FE Test #1Direct Exposure – Neglect Coupled Thermal Direct Exposure – Neglect Coupled Thermal

StressesStresses

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Test #2:Test #2:Direct Exposure – Include Thermal StressesDirect Exposure – Include Thermal Stresses

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Test #3Test #3Asymmetric ThrustAsymmetric Thrust

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Test #4Test #4Unevenly Distributed LoadUnevenly Distributed Load

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Test #5Test #5Unevenly Distributed Load Unevenly Distributed Load

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FE ConclusionsFE Conclusions Thermal Loading Not Worth CostThermal Loading Not Worth Cost Hardening Strip CorrectionsHardening Strip Corrections All Deflections are ReasonableAll Deflections are Reasonable FE Model Can Be Used for Future FE Model Can Be Used for Future

AnalysisAnalysis Recommendation: Crack PropagationRecommendation: Crack Propagation

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Orbital Trajectory SimulationOrbital Trajectory SimulationPaul MearsPaul Mears

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Simulation TopicsSimulation Topics Review: Four Body Problem with Review: Four Body Problem with

Thrust Thrust Review: Initial ConditionsReview: Initial Conditions Rotating Thrust VectorRotating Thrust Vector Umbra and PenumbraUmbra and Penumbra Results: OrbitsResults: Orbits Measuring Thrust with Observations Measuring Thrust with Observations

and Simulations and Simulations

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Four Body Problem with ThrustFour Body Problem with Thrust Physics Models:Physics Models:

• Newton’s Law of GravitationNewton’s Law of Gravitation• Earth orbit perturbed by the Sun and the MoonEarth orbit perturbed by the Sun and the Moon

• Solar Radiation PressureSolar Radiation Pressure• Generates thrust based on distance from Sun and Generates thrust based on distance from Sun and

sail attitudesail attitude

• Other Orbital MechanicsOther Orbital Mechanics• Initial Conditions, Sun and Moon Position VectorsInitial Conditions, Sun and Moon Position Vectors

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Initial ConditionsInitial Conditions

CubeSat requires low altitudes due to costCubeSat requires low altitudes due to cost

PerigeePerigeeLEO altitudeLEO altitudeHighest velocityHighest velocity

ApogeeApogeeGEO altitudeGEO altitudeLowest velocityLowest velocity

Result: Highly eccentric orbit (e=0.74)Result: Highly eccentric orbit (e=0.74)

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Rotating Thrust VectorRotating Thrust Vector Thrust acts along the sail normal Thrust acts along the sail normal

vector.vector. Sail normal is rotated in three Sail normal is rotated in three

dimensions.dimensions.

Z

Y

X)(t

)(t

NS

tβββ

tααα

0

0

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Umbra and PenumbraUmbra and Penumbra When the sail enters the Umbra, thrust is When the sail enters the Umbra, thrust is

zerozero Penumbra effects are ignoredPenumbra effects are ignored

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Results: ThrustResults: Thrust Thrust Generated by Solar Radiation Thrust Generated by Solar Radiation

Pressure is:Pressure is:

)(100.5 10avg NT

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Results - Orbit1: No Rotation Results - Orbit1: No Rotation

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Orbit 3: Rotating Thrust VectorOrbit 3: Rotating Thrust Vector

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Orbit 4: Rotating Thrust VectorOrbit 4: Rotating Thrust Vector

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Orbit 5: Rotating Thrust VectorOrbit 5: Rotating Thrust Vector

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Measuring ThrustMeasuring Thrust Purpose of simulation is to compare Purpose of simulation is to compare

simulated orbit to observed orbitsimulated orbit to observed orbit

Two possible situations:Two possible situations:1.1. Thrust accurately predicted by sail Thrust accurately predicted by sail

manufacturer.manufacturer. Observed orbit equals simulated orbitObserved orbit equals simulated orbit

2.2. Thrust generated is different from prediction.Thrust generated is different from prediction. Comparison of simulated and observed orbits to Comparison of simulated and observed orbits to

determine thrustdetermine thrust

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Comparison TechniqueComparison Technique

1.1. Make several observations of position Make several observations of position and attitudeand attitude

Calculate orbit and sail rotation rateCalculate orbit and sail rotation rate

2.2. Simulate orbit for known orbital elements Simulate orbit for known orbital elements and rotating sail normaland rotating sail normal

3.3. Extract thrust vector from equations of Extract thrust vector from equations of motionmotion

4.4. Calculate the magnitude of the thrust Calculate the magnitude of the thrust vectorvector

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Presentation OutlinePresentation Outline

Introduction

Propulsion

Tracking

ElectronicsStructure &Deployment

OrbitalSimulation

BudgetConclusion

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Budget SummaryBudget Summary Personnel CostsPersonnel Costs 15,00015,000 Materials & ElectronicsMaterials & Electronics 06,50006,500 Testing (CalPoly)Testing (CalPoly) 02,00002,000 LaunchLaunch 50,00050,000

TotalTotal 73,50073,500

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ConclusionConclusion PaperSat has developed a picosatellite design for PaperSat has developed a picosatellite design for

the CubeSat programthe CubeSat program Design will test solar sail propulsion technologyDesign will test solar sail propulsion technology Design will not incorporate attitude controlDesign will not incorporate attitude control Position, acceleration, and orientation will be Position, acceleration, and orientation will be

measured from ground stationsmeasured from ground stations Solar sail will be reflective on both sides with tear Solar sail will be reflective on both sides with tear

strips, hardening strips and inflation capillariesstrips, hardening strips and inflation capillaries Orbital simulation provides prediction of satellite Orbital simulation provides prediction of satellite

orbit for thrust determinationorbit for thrust determination

http://www.ae.utexas.edu/design/papersat/http://www.ae.utexas.edu/design/papersat/

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AcknowledgementsAcknowledgements Dr. Wallace FowlerDr. Wallace Fowler Dr. Cesar OcampoDr. Cesar Ocampo Dr. Eric BeckerDr. Eric Becker Meredith FitzpatrickMeredith Fitzpatrick Previous CubeSat Design GroupsPrevious CubeSat Design Groups

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QuestionsQuestions