Large Deployable Reflector on Engineering Test Satellite VIII

Transcription

1 Large Deployable Reflector on Engineering Test Satellite VIII Japan Aerospace Exploration Agency Space Applications Mission Directorate Satoru OZAWA 1

2 Today s Talk 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? 2

3 What is the Engineering Test Satellite VIII? 3

4 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 146ºE longitude Solar Array Paddle 4 Design life 10 years (s/c) 3 years (mission)

5 Objective of Engineering Test Satellite VIII Mobile Communication Satellite N-STAR ETS-VIII LARGE Portable size terminal SMALL Handheld size terminal 5

6 Target of Engineering Test Satellite VIII solid 30 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 Aperture [m] 6

7 What is Large Deployable Reflector? 7

8 Overview 17m Type Size Nominal aperture Number of modules Offset angle Offset Parabola About 19m x 17m 13m (inscribed circle) º Stiffness 0.09Hz or more 19m Accuracy 2.4mmrms or less 8 Weight Density 105kg (reflector) 650g/m 2

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

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

11 Development strategy of Large Deployable Reflector 11

12 Development strategy of the Large 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 12

13 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 Large Deployable Reflector 13

14 Two main pillars Module and Analysis Two main pillars module analysis 14

15 Modular mesh antenna concept module Modular mesh antenna concept 15

16 Deployment force vs. Gravity Deployment force Counter force Large deployable structure Gravity >> Deployment force Errors >> Deployment Force Gravity force Unable to evaluate deployment force 16

17 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. Large aperture for use m 2.0m antenna aperture [m] Difficulty of deployment test 17 We apply the modular mesh antenna concept.

18 Development strategy of Large Deployable Reflector analysis High precision deployment analysis 18

19 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. 19

20 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 Large Deployable Reflector 20

21 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 Large Deployable Reflector 21

22 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 Large Deployable Reflector 22

23 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) 23

24 LDREX-2 deployment procedure and result 24

25 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. 25

26 Evaluation of Large 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 26

27 Worst case analysis results of the Large 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. 27

28 In-orbit deployment of Large Deployable Reflector 28

29 Launch of Engineering Test Satellite VIII Final tests Stacked on fairing 29 Launched on 18 Dec 2006

30 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 30 regular mode

31 Deployment sequence 31

32 Deployment (1/2) 32

33 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. 33

34 Applications of Large Deployable Reflector 34

35 Applications of the Large Deployable Reflector large ETS-8 non ellipse 30m class LDR high accuracy one large reflector ASTRO-G 35 InSAR Data relay

36 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 manufactureof each module. 36

37 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. 37

38 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. 38

39 Concluding remarks 39

40 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, interferometeric synthetic aperture radars, communications and broadcastings. 40

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