Large Deployable Reflector on Engineering Test Satellite VIII Large ...

<strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
on
Engineering Test Satellite VIII
Japan Aerospace Exploration Agency
Space Applications Mission Directorate
Satoru OZAWA
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Today’s Talk
<strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong> (LDR)
What is Engineering Test Satellite VIII
What is <strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
Development strategy of LDR
In-orbit deployment of LDR
What are Future Space Applications
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What is the Engineering Test Satellite VIII
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Overview of the
Engineering Test Satellite VIII
LDR
for reception
LDR
for transmission
40m
40m
Type
Frequency
band
Mass
Electric
power
Orbit
Communication
satellite
S band
3000 kg on-orbit
at start of mission
7.5 kW
146º E longitude
Solar Array Paddle
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Design life
10 years (s/c)
3 years (mission)

Objective of
Engineering Test Satellite VIII
Mobile Communication Satellite
N-STAR
ETS-VIII
LARGE
Portable size terminal
SMALL
Handheld size terminal
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Target of
Engineering Test Satellite VIII
solid
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CS
Italsat ARTEMIS ETS-VI
Ka
Frequency [GHz]
10
5
AMSC
ETS-VI
N-STAR
GSTAR
INTERSAT6
Palapa C
TDRS
N-STAR
Galaxy 3
Telecom2 INTERSAT7
Telecom2
Arabsat2 TDRS
beam diameter constant
mesh
ETS-VIII
inflatable
Ku
C
S
1
ARTEMIS
AMSC
M-SAT
ACeS
L'Garde
L
0 5 10 15 20
Aperture [m]
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What is <strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
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Overview
17m
Type
Size
Nominal
aperture
Number of
modules
Offset angle
Offset Parabola
About 19m x 17m
13m
(inscribed circle)
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51.2º
Stiffness
0.09Hz or more
19m
Accuracy
2.4mmrms or less
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Weight
Density
105kg (reflector)
650g/m 2

Composition of each module
Surface cable
(Quartzel)
Surface mesh
(Gilded molybdenum)
Circumference mesh
(Gilded molybdenum)
<strong>Reflector</strong> surface
Tie/Back cables
(Quartzel)
Circumference cables
(Quartzel)
<strong>Deployable</strong> truss
Support structure
Tendon cable

Support structure
4.8m
Radial truss structure.
Spring deploys structure.
Motor controls deployment
speed and enables rewind.

Development strategy
of <strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
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Development strategy of the
<strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
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 <strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
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Two main pillars
Module 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 <strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
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Two main pillars
Module and Analysis
Two main pillars
module
analysis
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Modular mesh antenna concept
module
Modular mesh antenna concept
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Deployment force vs. Gravity
Deployment force
Counter force
<strong>Large</strong> deployable
structure
Gravity >> Deployment force
Errors >> Deployment Force
Gravity force
Unable to evaluate
deployment force
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Ground test difficulty evaluation
10 5
DDT
=
gravity force
deployment force
Unfeasible zone
10 4
LDR 14 module
DDT
10 3
unfurlable antenna
fan-rib
d = 0.5m LDR 1 module
LDR 7 module
VSOP
hoop-column
Small aperture for
test/manufacturing.
<strong>Large</strong> aperture for use.
10 2
1.0m 2.0m
10 1 0.0 10.0 20.0
antenna aperture [m]
Difficulty of deployment test
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We apply the modular
mesh antenna concept.

Development strategy of
<strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
analysis
High precision deployment analysis
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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 Telegraph
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 pillars
Module and Analysis
Ground tests and Updating analysis model
High accurate surface forming
Analysis precision evaluation by LDREX-2
Evaluation of <strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
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High accurate surface forming
Strategy
Two important pillars
Module and Analysis
Ground tests and Updating analysis model
High accurate surface forming
Analysis precision evaluation by LDREX-2
Evaluation of <strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
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Analysis precision evaluation by LDREX-2
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 <strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
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Analysis precision evaluation by the
LDREX-2 in-orbit experiment
6.5m
Mass
Size
Number of
modules
Launcher
211 kg
6.5m x 6.5m
7
Ariane 5ECA
Orbit
GTO
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 <strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
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 <strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
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Worst case analysis results of the
<strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
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 deployment
of <strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
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Launch of
Engineering Test Satellite VIII
Final tests
Stacked on fairing 29 Launched on 18 Dec 2006

Events of
Engineering Test Satellite VIII
Boom extension
+X
+X
+Z
3 axes stabilized
geostationary
drift orbit
+Z
+Z
+X
Tx LDR deployment
+Z +Z
+X
Rx LDR deployment
+X
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regular mode

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 <strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>s 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 <strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
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Applications of the
<strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>
large
ETS-8
non ellipse
30m class LDR
high accuracy
one large reflector
ASTRO-G
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InSAR
Data relay

Application to
High 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 to
Very 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 to
a 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
<strong>Large</strong> <strong>Deployable</strong> <strong>Reflector</strong>s mounted on
Engineering Test Satellite VIII were successfully
deployed.
The two important pillars of <strong>Large</strong> <strong>Deployable</strong>
<strong>Reflector</strong> 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, interferometeric
synthetic aperture radars, communications and
broadcastings.
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