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Large Deployable Reflectoron

Engineering Test Satellite VIII

Large Deployable Reflectoron

Engineering Test Satellite VIII

Japan Aerospace Exploration Agency

Space Applications Mission Directorate

Satoru OZAWA

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Large Deployable Reflector (LDR)

� What is Engineering Test Satellite VIII?

� What is Large Deployable Reflector?

� Development strategy of LDR

� In-orbit deployment of LDR

� What are Future Space Applications?

Today’s Talk

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What is the Engineering Test Satellite VIII?

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Overview of theEngineering Test Satellite VIII

40m

40m

LDR

for transmission

LDR

for reception

Solar Array Paddle

S bandFrequency

band

Communication satellite

Type

146º E longitude Orbit

10 years (s/c)

3 years (mission)Design life

7.5 kWElectric power

3000 kg on-orbit at start of mission

Mass

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Handheld size terminal

ETS-VIIIN-STAR

Portable size terminal

Objective ofEngineering Test Satellite VIII

Mobile Communication Satellite

LARGE

SMALL

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Target ofEngineering Test Satellite VIII

Aperture [m]

Fre

qu

en

cy [

GH

z]

beam diameter constant

solid

mesh

inflatable

0 5 10 15 20

CS ItalsatARTEMIS

ETS-VI

ETS-VI

AMSC

INTERSAT6

Palapa C

GSTARTDRS

N-STAR

N-STARGalaxy 3

INTERSAT7Telecom2

Telecom2Arabsat2

AMSC

M-SAT

TDRS

ARTEMIS L'GardeACeS

Ka

Ku

C

S

L

1

5

10

30

ETS-VIII

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What is Large Deployable Reflector?

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Overview

About 19m x 17mSize

0.09Hz or moreStiffness

14Number of modules

105kg (reflector)

650g/m2

Weight

Density

2.4mmrms or lessAccuracy

51.2ºOffset angle

13m

(inscribed circle)Nominal aperture

Offset ParabolaType

19m

17m

Deployable truss

Surface cable(Quartzel)

Surface mesh(Gilded molybdenum)

Tie/Back cables(Quartzel)

Circumference mesh(Gilded molybdenum)

Circumference cables(Quartzel)

Tendon cable

Composition of each module

Support structure

Reflector surface

Support structure

� Radial truss structure.

� Spring deploys structure.

� Motor controls deployment speed and enables rewind.

4.8m

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Development strategyof Large Deployable Reflector

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Development strategy of theLarge Deployable Reflector

Strategy

� Two main pillars:Module and Analysis

� Ground tests and Updating analysis model

� High accurate surface forming

� Analysis precision evaluation by LDREX-2

� Evaluation of Large Deployable Reflector

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Two main pillarsModule and Analysis

Strategy

� Two main pillars:Module and Analysis

� Ground tests and Updating analysis model

� High accurate surface forming

� Analysis precision evaluation by LDREX-2

� Evaluation of Large Deployable Reflector

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Two main pillarsModule and Analysis

module analysis

Two main pillars

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Modular mesh antenna concept

moduleModular mesh antenna concept

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Deployment force vs. Gravity

Gravity force

Deployment force

Large deployable structure

Gravity >> Deployment force

Errors >> Deployment Force

Unable to evaluatedeployment force

Counter force

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Ground test difficulty evaluation

Unfeasible zone

antenna aperture [m]

DD

T

LDR 14 module

fan-rib

d = 0.5m

1.0m2.0m

unfurlable antenna

VSOP

hoop-column

105

104

103

102

101

0.0 10.0 20.0

LDR 7 module

LDR 1 module

Difficulty of deployment test

gravity forceDDT

deployment force=

� Small aperture for test/manufacturing.

� Large aperture for use.

We apply the modular

mesh antenna concept.

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Development strategy ofLarge Deployable Reflector

High precision deployment analysisanalysis

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Deployment analysis technology for high precision prediction

SPADE Origami/ETS

SPADE was made for high precision deployment analyses by NTT (Nippon Tele-

graph and Telephone Corporation). Currently Orgami/ETS inherits its technology and is still being expanded by JAXA. These software contributed to LDR.

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Update analysis model by ground tests

Strategy

� Two main pillarsModule and Analysis

� Ground tests and Updating analysis model

� High accurate surface forming

� Analysis precision evaluation by LDREX-2

� Evaluation of Large Deployable Reflector

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High accurate surface forming

Strategy

� Two important pillarsModule and Analysis

� Ground tests and Updating analysis model

� High accurate surface forming

� Analysis precision evaluation by LDREX-2

� Evaluation of Large Deployable Reflector

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Analysis precision evaluation by LDREX-2

Strategy

� Two main pillarsModule and Analysis

� Ground tests and Updating analysis model

� High accurate surface forming

� Analysis precision evaluation by LDREX-2

� Evaluation of Large Deployable Reflector

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Analysis precision evaluation by theLDREX-2 in-orbit experiment

Ariane 5ECALauncher

GTOOrbit

7Number of modules

6.5m x 6.5mSize

211 kgMass6.5m

ASAP5(ARINE5 Structure for Auxiliary Payload)

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LDREX-2 deployment procedure and result

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Analysis precision evaluation by LDREX-2

Analysis result agreed with experiment within 10% at almost every angle. The

maximum error is 32% right before full deployment. Analysis simulates well and can be used for in-orbit prediction of LDR.

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Evaluation of Large Deployable Reflector

Strategy

� Two main pillarsModule and Analysis

� Ground tests and Updating analysis model

� High accurate surface forming

� Analysis precision evaluation by LDREX-2

� Evaluation of Large Deployable Reflector

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Worst case analysis results of theLarge Deployable Reflector

The evaluation of in-orbit deployment of LDR with maximum 32% error

considered shows that the deployment force margin is greater than 2. The reflector is guaranteed to deploy through the analysis and LDREX-2.

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In-orbit deploymentof Large Deployable Reflector

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Launch ofEngineering Test Satellite VIII

Final tests

Stacked on fairing Launched on 18 Dec 2006

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Tx LDR deployment

Events ofEngineering Test Satellite VIII

geostationary

drift orbit

regular mode

3 axes stabilized

+Z

+X

+X

+Z

+Z

+X

+X

+Z +Z

+X

Rx LDR deployment

Boom extension

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Deployment sequence

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Deployment (1/2)

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Deployment (2/2)

Deployed Rx LDR Deployed Tx LDR

The in-orbit deployment of Large Deployable Reflectors demonstrated that the

modular mesh antenna concept and the high precision analysis technology are

very effective. Furthermore, it is also confirmed that the surface accuracy

satisfies the specification against thermal environments throughout the year. These methods can be used for various applications.

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Applications of Large Deployable Reflector

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ETS-8

ASTRO-G

30m class LDR

InSAR

Data relay

Applications of theLarge Deployable Reflector

non ellipse

high accuracy

large

one large reflector

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Application toHigh accuracy reflector

ASTRO-G

� Radio astronomy

� 9.26m aperture

� 0.4mmrms surface accuracy for 43GHz observation

The modular mesh antenna concept can achieve the desired accuracy by the

adjustment and measurement of its surface during the manufacture of each module.

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Application toVery large reflector

30m class reflector

� Mobile communication

� 30m aperture

� S band

The modular mesh antenna concept can enlarge deployable reflectors by extending each module’s aperture or increasing the number of modules.

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Application toa variety of missions

InSAR Data relay

The modular mesh antenna concept can be applied to a huge variety of missions

by changing the combination of modules, incorporating high precision modules, increasing the number of modules, and enlarging modules.

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Concluding remarks

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Concluding remarks

� Large Deployable Reflectors mounted on Engineering Test Satellite VIII were successfully deployed.

� The two important pillars of Large Deployable Reflector are the modular mesh antenna concept and the high precision analysis technology.

� The modular mesh antenna concept can be applied to a huge variety of missions, such as radio astronomy missions, interferometericsynthetic aperture radars, communications and broadcastings.

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