1. Spacecraft Design and Sizing Dr Andrew Ketsdever MAE 5595 Lesson 14

2. Spacecraft Design and Sizing Sizing Introduction Big Picture: The Mission drives the Payload and the Orbit, which drives the Spacecraft Design

3. Spacecraft Design and Sizing Overview of Spacecraft Design & Sizing

4. Spacecraft Design and Sizing Principal Requirements & Constraints for S/C Design

6. Spacecraft Design and Sizing Weight Budget

7. Spacecraft Design and Sizing Spacecraft Configuration Drivers

8. Spacecraft Design and Sizing Can use historical data for next block of same S/C, or to generalize within a mission type

9. Spacecraft Design and Sizing Mass Distribution for Selected Satellites

10. Spacecraft Design and Sizing

11. Spacecraft Design and Sizing Mass Distribution for Selected Satellites

12. Spacecraft Design and Sizing Top-Down Sizing Example Given: navigation mission with m P/L = 50 kg Find: subsystem masses and m dry

13. Spacecraft Design and Sizing Top-Down Sizing Example Still need other masses to permit eventual launch vehicle choice m kick is apogee kick motor – if needed m adapter counts against booster performance #s Need to include margin

14. Spacecraft Design and Sizing S/C Budgets For top-down designs, allocate so much of a quantity or capability to each subsystem Types of budgets –Mass –Power –Communication bandwidth –Volume –Reliability –Pointing error –Cost –Schedule, etc

15. Spacecraft Design and Sizing Mass Budget See previous navigation S/C example → Now add mass margin into calculation Margin covers the uncertainty in our estimates –Typical range from 5% to 25% –Larger margin for new S/C, or earlier in design phase –Smaller margin for known S/C, or as design progresses

16. Spacecraft Design and Sizing Preparing a Power Budget

17. Spacecraft Design and Sizing Typical Power Consumption by Module or Subsystem

18. Spacecraft Design and Sizing Propellant Budget List  v’s Use ideal rocket equation to convert  v to propellant mass

19. Spacecraft Design and Sizing Propellant Budget

20. Spacecraft Design and Sizing Estimating Spacecraft Equipment Compartment Dimensions