Preliminary design and stability analysis of ade-orbiting system for CubeSats

Guerric de Crombrugghe & Laurent Michiels

Promoters: Pr. P. Chatelain (EPL) & Pr. Th. Magin (VKI)

Supervisor: C. Asma (VKI)

Ecole Polytechnique de Louvain, UCLouvain

January 29, 2012

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PART I: INTRODUCTION

PART II: OBJECTIVES

PART III: PROJECT STRATEGY

PART IV: APPLICATION

PART V: CONCLUSION AND PERSPECTIVES

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PART I: INTRODUCTION

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Origin of the idea: Two major concerns (1/3)

1. Atmospheric re-entry

• Key for space exploration• human spaceflight• robotic exploration on Mars, Venus,

and even Titan

• Validation tools• costly• extended development timeline

2. Debris mitigation

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Origin of the idea: Two major concerns (2/3)

1. Atmospheric re-entry

2. Debris mitigation

• Unexpected collisions betweensatellites

• Guidelines: on orbit   25 years afterthe mission’s end

• difficult to respect• especially for small satellites

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Origin of the idea: Two major concerns (3/3)

1. Atmospheric re-entry

2. Debris mitigation

Ñ Need for CubeSat re-entry vehicle

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Opportunity: QB50 (1/2)

Mission

• Initiated by the von KarmanInstitute for Fluid Dynamics

• Dedicated to in-situ exploration ofthe lower thermosphere

• Network of over fifty CubeSats

• Some of them will experience acontrolled re-entry

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Opportunity: QB50 (2/2)

Breakthrough

• QB50 opens a new type ofmissions: very low Earth orbit

• Allows for affordable in-orbitdemonstration

• New environment need forinnovative stability and de-orbitingsystem

Credits: G. Bailet

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PART II: OBJECTIVES

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Objectives

No spacecraft with such reduced dimension has ever performed acontrolled re-entry.

The challenges

• Communication: no recovery

• De-orbiting: short timescale to avoid passing over the poles

• Thermal loads: keeping the electronics below 70�C

• Stability: heat shield facing the flow

satellite’s trajectoryEarth

Ñ

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Objectives

No spacecraft with such reduced dimension has ever performed acontrolled re-entry.

The challenges

• Communication: no recovery

• De-orbiting: short timescale to avoid passing over the poles

• Thermal loads: keeping the electronics below 70�C

• Stability: heat shield facing the flow

satellite’s trajectoryEarth

Ñ

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PART III: PROJECT STRATEGY

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Survey of de-orbiting techniques (1/3)

PropulsionSatellite slowed down with an engine (chemical, cold gas, or electrical)providing thrust against its movement.

• Integration issues

• Manoeuvre complexity

Credits: ATK

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Survey of de-orbiting techniques (2/3)

TethersSatellite slowed down by electromagnetic interactions between a tetherand the Earth’s magnetic field.

• Low Technology Readiness Level (TRL)

• De-orbiting duration to count in years

Credits: NASA

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Survey of de-orbiting techniques (3/3)

Aerodynamic dragSatellite slowed down by the atmosphere.

• Fits the requirement enveloppe

• Allows for passive stabilization if well-dimensionned

Credits: NASA

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2D re-entry stability model (1/2)

Sum of forces: m BvBt� �Fg er �D eD � L eL

Sum of moments: BωBt�

Mz

Jzzez

Fg �G �MEarth

|r|2m

D � ρphq � CDph, αq �v2

2� Aref

L � ρphq � CLph, αq �v2

2� Aref

Mz � ρphq�v2

2�Aref �Lref �pC

αMph, αq�CMωph, αq�ωq

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2D re-entry stability model (2/2)

OutputAltitude, velocity, acceleration and angle of attack for every point of theobject’s trajectory.

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Numerical computation (1/2)

Rarefied flows vs continuum flows

• the satellite will experience from free-molecular while on orbit tocontinuum in lower altitudes

• degree of rarefaction defined by the Knudsen number Kn � λL

• experimentation of rarefied flows: complex and expensiveÑ numerical approach: Direct Simulation Monte Carlo (DSMC)

Y

Z

X

Mach

1412108642

Kn = 30.2Altitude = 130 kmFlow direction Ð

X Y

Z

Mach

2218141062

Kn = 2.14Altitude = 110 kmFlow direction Ð

X Y

Z

Mach

25211713951

Kn = 0.345Altitude = 100 kmFlow direction Ð

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Numerical computation (2/2)

Z

X

Y

# collisions / particle / s

26002400200016001200800

Number of collision perunit of volumeAltitude = 110 kmFlow direction Ð

Z

X

Y

Pressure (Pa)

0.450.350.250.150.05

PressureAltitude = 110 kmFlow direction Ð

Output

• Aerodynamic coefficient characterising the object as a function ofthe altitude / angle of attack.

• Flow-field description (pressure, temperature, number of collisions,etc.) allows for defining the interesting geometrical features.

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PART IV: APPLICATION

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Geometry design

BasicDirection of flight: Ò

BadmintonDirection of flight: Ò

FlowerDirection of flight: Ò

PlateDirection of flight: Ò

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Aerodynamic characteristics

10−2

100

102

104

106

1.6

1.8

2

2.2

2.4

2.6

2.8

3

Knudsen number

Dra

g c

oeffic

ient

angle of attack: 0°

angle of attack: 15°

rarefiedregime

continuumregime

transition

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Flight characteristics: Basic geometry

satellite’s trajectoryEarth

0 5 10 15100

110

120

130

140

150

160

170

180

Time (hours)

Alti

tude

(km

)

initial angle of attack: 0°initial angle of attack: 15°

107.7 km

100120140160−15

−10

−5

0

5

10

15

Altitude (km)

Ang

le o

f atta

ck (

°)

107.7km

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Flight characteristics: Plate geometry

satellite’s trajectoryEarth

0 50 100 150100

110

120

130

140

150

160

170

Time (minutes)

Alti

tude

(km

)

901101301501707720

7760

7800

7840

Altitude (km)

Abs

olut

e ve

loci

ty (

m/s

)

satellite’s velocityorbital velocity

115 m/s

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Geometry selection

• better for de-orbiting but slightly less efficient for stabilization

• more degrees of freedom

• more likely to resist

• less points of failure

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Design

• Pressure is not a problematic issue

• Passive deployment based on the drag is not possible

• Materials should be chosen for their thermal properties

• A 1 m link is optimal

• A 1 m2 plate is enough, more is not interesting

0.09 m2

satellite’s trajectoryEarth

1 m2 2 m2

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Flight characteristics: Influence of the mass

plate of 0.09 m2

0 1 2 3100

110

120

130

140

150

160

170

Time (hours)

Alti

tude

(km

)

mass: 3kgmass: 2kgmass: 4kg

Re-writing sum of forces: BvBt � �

GM|r|2

er �Dm eD �

Lm eL

Ñ The lower the mass, the greater the effect of the aerodynamic forces

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Flight characteristics: Influence of the atmospheric model

plate of 0.09 m2

0 1 2 3100

110

120

130

140

150

160

170

Time (hours)

Alti

tude

(km

)

JacchiaMSISE90 − medium activityMSISE90 − high activityMSISE90 − low activity

Expected launch window during low solar activity

Ñ Longer re-entry duration

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Flight characteristics: Influence of the trigger altitude

plate of 0.09 m2

1001201401601802000

10

20

30

40

50

60

70

80

Altitude (km)

Rad

ial v

eloc

ity (

m/s

)

trigger altitude: 150kmtrigger altitude: 200kmtrigger altitude: 170km

Trigger altitude has only an influence in the beginning the trajectory.

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PART V: CONCLUSION AND PERSPECTIVES

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Achievements

• 2D re-entry simulation tool• more accurate• adaptable to every geometry

• Design of a de-orbiting and stabilization device for QB50 re-entrysatellite

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Perspectives

• Further development of the system’s design

• Upgrade of the Simulink program

• Complete the aerodynamic coefficients databases

• Investigation of the non-monotonic behaviour of the aerodynamiccoefficients

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THANK YOUAny questions?

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