Gravity Gradient Boom

Design Team: Arthur Inglot, Jack Rafalowski, Gene Rossov, Steve Souza, Jason Stricker

Sponsor: John Hines

In Collaboration with:

Advisor: Gregory Kowalski

What is a Gravity Gradient Boom

Retracted Deployed

Boom ArmTip Mass

Satellite

Boom Stowed

Attitude ControlAttitude Control

Satellite stabilization Satellite stabilization and controland control Purpose:Purpose:

Maintain communication link to Maintain communication link to satellites antennassatellites antennas

Maintain a desired view for Maintain a desired view for imagingimaging

Heat dissipation and distributionHeat dissipation and distribution

Three AxesThree Axes LocationLocation DirectionDirection

Boom Deployed

Problem StatementProblem Statement

Design and develop a Gravity Gradient Boom as a stand alone Passive Attitude Control for a small satellite, conforming to the requirements put forth by NASA.

ONYXONYX

Project developed by Santa Clara U (Ca)Project developed by Santa Clara U (Ca) Collaboration with NASA, AFOSR and DARPA and part of the Collaboration with NASA, AFOSR and DARPA and part of the

University Nanosatellite Program University Nanosatellite Program OnOnboard autonomboard autonomyy e exxperimentperiment

Purpose:Purpose: To monitor anomalies in orbital motion and resolve them using To monitor anomalies in orbital motion and resolve them using

two independent processing systems autonomously while two independent processing systems autonomously while observing Earth. observing Earth.

Image capturing in multiple spectrumsImage capturing in multiple spectrums Research tool and educational service for K-12 and college Research tool and educational service for K-12 and college

students.students.

ONYXONYX

•30kg

•21cm/hexagonal sides x 42cm tall

•Center of gravity location [X, Y, Z]: [-0.326, 15.5, -0.170] cm

•Moment of inertia about CG: XX: 5.3E6g*cm2

YY: 4.6E6g*cm2

ZZ: 5.0E6g*cm2

Requirements and ConstraintsRequirements and Constraints

Orientation requirements:Orientation requirements: +/- 5 degrees+/- 5 degrees Constraints:Constraints:

MassMass:: <10 kg<10 kg Volume/DimensionsVolume/Dimensions:: 12 x 12 x 15 cm (.00216m12 x 12 x 15 cm (.00216m33 )) PowerPower:: << 30 watts30 watts

Opening on top:Opening on top: 10 cm x 10 cm10 cm x 10 cm

Preliminary Damping:Preliminary Damping: ProvidedProvided

Shock Resistance:Shock Resistance: ±20 Gs±20 Gs

Min. Resonance Freq.:Min. Resonance Freq.: 500 Hz500 Hz

Newton’s Law of Universal Newton’s Law of Universal GravitationGravitation

Low Earth Orbit is 200km-2000kmLow Earth Orbit is 200km-2000km

Mass of Earth is Mass of Earth is 5.9742 x 105.9742 x 102424 kgkg

Radius of Earth is Radius of Earth is 6380 km6380 km

G is the universal constant, G is the universal constant, 6.67 x 106.67 x 10-11-11NmNm22/kg/kg22

The Whole PictureThe Whole Picture

Offset Initial Angle and DampeningOffset Initial Angle and Dampening

Deployment OptionsDeployment Options

Telescoping BoomsTelescoping Booms High torsion and bending High torsion and bending

strengthstrength Intended for many cyclesIntended for many cycles Extreme deployment and Extreme deployment and

retraction forceretraction force

TethersTethers Complicated and costlyComplicated and costly Motor unwinds long Motor unwinds long

lengths of tether material lengths of tether material (2 Km)(2 Km)

Oscillation and reliability Oscillation and reliability concernsconcerns

Prone to space collisionsProne to space collisions

Coilable BoomCoilable Boom Very light weight (< 50g/m)Very light weight (< 50g/m) Stowage size is very smallStowage size is very small Low costLow cost High ReliabilityHigh Reliability

Wire Drum DeployerWire Drum Deployer

Copper-Beryllium Wire wound on a drumCopper-Beryllium Wire wound on a drum Proven Technology with industry backingProven Technology with industry backing Copper-Beryllium provides sufficient tension Copper-Beryllium provides sufficient tension Can be deployed using an electric motor or a passive Can be deployed using an electric motor or a passive

spring assemblyspring assembly Low weight, low cost, and space saving packaging Low weight, low cost, and space saving packaging Due to low weight of overall wire deployer a heavier tip Due to low weight of overall wire deployer a heavier tip

mass may be used to provide more stabilization mass may be used to provide more stabilization Have to account for physical and thermal oscillations, Have to account for physical and thermal oscillations,

additional hardware such as dampers may have to be additional hardware such as dampers may have to be implementedimplemented

Design MatrixDesign MatrixWeight Factor

Multiplier :3X 3X 2X 2X 1X 2X 4X 2X 4X 1X 2X

Deployment Type/Boom

Size/Volume WeightMechanical Complexity

RetractabilityThermal

CharacteristicsPossible Length

Adaptability to other missions

Structural Predictability

Damping/Dynamic

ResponsePower Cost

Wire/Drum 3.8 3.2 3.8 3.4 3 3.8 4 3.2 2.6 3 3.4

Telescoping Tubular 1.6 1.4 2.4 2.8 2.4 2 2.8 3.2 3.6 1.8 2

Tether 1.8 2.2 2 1.6 2 2.2 1.8 1.4 1.6 1.6 2

Coilable 2.8 3.4 1.8 1.8 2.6 2 1.4 2.2 2.2 3.6 2.6

Deployment Type/Boom

Totals

Wire/Drum 88.6

Telescoping Tubular 63.6

Tether 47.6

Coilable 60

Wire Deployment SystemWire Deployment System

Tungsten Alloy Tip Mass

Delrin Mounting Ring

Frangibolt ® system

Copper Beryllium Wire Spool

Release Solenoid

Deployment Spider

Aluminum 6061 Machined Components

Stowed Configuration Deployed Configuration

The Frangibolt ® SystemThe Frangibolt ® System

•Non-Explosive Actuator

•High Factor of safety

•Consumes 25 Watts

•Yield strength 2200 N

•Compact size

•Flight certified with space heritage

Wire Deployer Wire Deployer

Mounted Deployed

Cosmos Deformation AnalysisCosmos Deformation Analysis

6.295E6 N/m2 6.295E6 N/m2

Final Optimized Decisions for Final Optimized Decisions for MATLAB InputMATLAB Input

Length of wire:Length of wire: 20.0 m20.0 m Tip Mass:Tip Mass: 3.00 kg3.00 kg Orbit:Orbit: CircularCircular Altitude:Altitude: 500km500km Inputing the parameters into the MATLAB Inputing the parameters into the MATLAB

program created from ONYX’s data show program created from ONYX’s data show resulted for stabilization.resulted for stabilization.

Stabilization GraphStabilization Graph

Settling Time:9.25 days from 30o +/- 5o tolerance

Proper StabilizationProper Stabilization Gravity Gradient Boom must overcome all disturbance Gravity Gradient Boom must overcome all disturbance

torques in spacetorques in space

Aero Dynamic Torque Aero Dynamic Torque 1.1 x 101.1 x 10-8 N-m

Solar Radiation TorqueSolar Radiation Torque 2.6 x 10-2.6 x 10-6 6 N-mN-m

Magnetic Field TorqueMagnetic Field Torque 8.6 x 10-8.6 x 10-4 4 N-mN-m

Torque Developed by GGBTorque Developed by GGB 3.2 x 10-3.2 x 10-3 3 N-mN-m

Final Optimized ConstraintsFinal Optimized Constraints

System Mass of 3.76kg, (6.24kg Under Max)System Mass of 3.76kg, (6.24kg Under Max)

Center of Mass and Moment of Inertia do not hinder Center of Mass and Moment of Inertia do not hinder

physical properties of the ONYX physical properties of the ONYX

High degree of accuracy with initial accuracy of 5 High degree of accuracy with initial accuracy of 5

degrees stabilizing to as low as 2 degreesdegrees stabilizing to as low as 2 degrees

Low Estimated cost of $4,000Low Estimated cost of $4,000

Highly adaptable to other satellites of similar sizeHighly adaptable to other satellites of similar size

ImprovementsImprovements

Improve modeling for FEA Vibration Improve modeling for FEA Vibration

analysisanalysis

Improve metal on metal contactImprove metal on metal contact

Integrate the use of a DC motor for more Integrate the use of a DC motor for more

controlcontrol

Any questions? Any questions?