1. 0 衛星結構設計 (II) 祝飛鴻 6/17/2004

2. 1  What you should learn from this course?  低軌道小衛星發展趨勢  Why spacecraft structure fails?

3. 2  What you should learn from this course?  Concept of System Engineering  Concept of Development Process  You may not have the opportunity to learn from other courses.  These 2 concepts can be applied to any field and will be extremely useful when you are in a management role or decision making position.

4. 3  Concept of System Engineering:  Each system can be logically or functionally break into subsystems.  Each subsystem is not a stand alone item but interface with each other by some means.  Best subsystem design will not lead to a best system. In some cases, best subsystem could lead to an unworkable system.  Iterative compromise between subsystems is unavoidable in achieving a workable system design.  A good system engineer must know the inter-relationship between subsystems and relative importance of each key parameter.

5. 4 Structure Subsystem EPS Type of solar array. Size Weight Area TT&C C&DH TCS ADCS RCS Radiation area Thermal conductivity Tank size Thruster alignment Size Weight Type of antenna Field of view Size Weight Field of view Alignment Weight Size

6. 5  Concept of Design Process:  Materialize the flow and steps necessary to complete the task. Mission Orbit Candidate LV Target Weight Fairing Size System & Subsystem Design Concept Hardware Selection Hardware Size Orientation & FOV Requirement Structure Configuration Mechanical Layout

7. 6 Target Weight Candidate LV Weight Allocation Heritage Data Design Concept System Design Weight Estimation Weight Re-allocation Preliminary Design Weight Calculation Detail Design Weight Reduction Final Weight Actual Weight Actual HW Over Weight ?

8. 7 低軌道小衛星發展趨勢

9. 8 Ref. 1: JPL Technology for Small Space Missions, Les Deutsch, March 29 2001 JPL Development Trend (Ref. 1)

10. 9 Formation Fly Paradigm Shift - same mission with lighter and smaller satellite -

11. 10 Single Large SpacecraftSingle Small Spacecraft  Limited by physical law and state-of- the-art technology Virtual Satellite Technology Breakthrough

12. 11  Satellite Design: Past, Present, and Future, Cyrus D. Jilla, International Journal of small satellite Engineering, 1997.  The Present:  Conventional subsystem by subsystem design  Modular design for multiple missions  Small satellite: low cost high risk design  The Future:  Multifunctional structures  Nanotechnology & MEMS systems  Distributed satellite system

13. 12 Solar Array - Specific Power  Current technology: ~200W/Kg.  Future goal: ~300W/Kg

14. 13 Li-ion 130Wh/Kg Battery - Specific Energy Thin-film lithium battery 300Wh/Kg NiH2 25-40Wh/Kg NiCd 25-30Wh/Kg Rechargeable lithium batteries sees as future. (Ref. 2)

15. 14  ADCS: (Ref. 2)  Compact, light weight sensors and components.  Integration of components (GPS & Attitude Sensors)  Complete spacecraft autonomy Sun Sensor Star Tracker Gyro

16. 15 Why spacecraft structure fails?

17. 16 Un-execusive Event

18. 17 Unforeseen Event

19. 18  Unfortunate Event

20. 19  Unlucky Event  Design Loads vs Coupled Loads Results  Random Vibration Loads  Shock loads Load Source Response Prediction

21. 20  Unforgivable Event  Design to failure  Analysis oversight  Over testing