1. Spacecraft Structures
Heather Reed
Mechanical Engineering Manager
Laboratory for Atmospheric and Space Structures

2. Why does a spacecraft need a structure? PRIMARY or Secondary?
What is a structure?
Why does a spacecraft need a structure?
PRIMARY or Secondary?

3. Lifecycle of a Structure
REQUIREMENTS
(NEEDS)
DESIGN
ANALYSIS
BUILD
TEST
INTEGRATION
STUDENT NITRIC OXIDE EXPLORER (SNOE)

4. REQUIREMENTS What does this spacecraft structure need to do?
Accessibility
Lift points
Vibe
Acoustic
Shock
Thermal
Radiation
GROUND
TESTING
ROCKET LAUNCH
ON-ORBIT
CONDITIONS

5. DESIGN – What shape will it be?
SNOE was a “spinner”

6. DESIGN – What will it be made out of?
Materials selection
Stiffness vs. Strength
Car suspension – STRONG CAR, weak connection to the road
WEIGHT  CHEAPEST RIDE TO SPACE = $35,000 per lb
Cleanliness
Specific plastics only
Materials that can be scrubbed
Aluminum is a great material

7. DESIGN – How will it be built?
Manufacturability
Strongest structure is all one piece
How easy is it to assemble?
Primary structure $$ < 1% of SNOE mission budget ($8M)

8. DESIGN – Will it fit? Solid Modeling Static or Dynamic SPACECRAFT
ROCKET
NOSECONE
ROCKET SECONDARY
STAGE
Solid Modeling
Static or Dynamic

9. Solid Modeling - SolidWorks

10. ANALYSIS - Modal Simulation Results
821 Hz: First predicted high mass participation mode.
Z-axis has very little mass participation below 2000 Hz.
741 Hz: Lowest frequency mode is a local connector bracket mode.
Two principal mode shapes shown below:
Mode 2 – 821 Hz – Mode shape plot
Rocking in the Y-direction
Mode 6 – 1270 Hz – Mode shape plot
Rocking in the X-direction

11. BUILDING IT – Your best laid plans
Fabrication – Do 2 planes meet perfectly?
Assembly – How clean is clean?

12. Why TEST? Vibration Testing Thermal Vacuum Testing Acoustic Testing
Shock Testing
Strength Testing
Spin Balance
Mass properties
NASA Goddard Gold Rules:
TEST AS YOU FLY, FLY AS YOU TEST

13. TESTING – Vibration Testing
Mass model testing – Good practice
Test sensors - Accelerometers
SNOE SPACECRAFT
LARGE SPEAKER
“VIBE TABLE”
AT BALL AEROSPACE

14. Vibration Test Specification

15. TESTING – Thermal Vacuum
Less cooling without air – Electronics
Thermal expansion – Causing binding
More friction without air – Moving parts
HOT/COLD Operational and Survival limits
SNOE SPACECRAFT
LARGE TANK
“RAMBO”
AT BALL AEROSPACE

16. INTEGRATION to the Pegasus

17. Secondary Structure – Solar Arrays

18. Heather Reed, CU Mechanical Eng 97’
Work during Undergrad studies, BS ME in 1995
Space Grant College
NIST, NDE lab
CU football & basketball security
Hart Ranch snack shop
Work during Grad studies on SNOE, MS ME in 1997
FEA, Solar panel substrate, Nutation damper, Torque rods, Thermal blankets
Employed at LASP after graduation
ME Manager in 2001, 8 ME’s then, 23 ME’s now
Current program is MAVEN, mission to MARS
Starting Program Management this week

19. EUV on MAVEN going to Mars
Langmuir Probe and Waves (LPW) – LASP / SSL
LPW/Extreme Ultra-Violet (LPW-EUV) – LASP
LPW-EUV

20. Testing Engineering Unit testing Flight Unit testing
Mechanism Life Testing – Vibe, Life Test cycling
Luxel filter qualification – Vibe, thermal cycles
Light leak testing
Torque margins
Spring force
Magnetic field
Flight Unit testing
Vibe test
Random Vibe, response limit
Strength verification = ?
Mechanism Run-in

21. Aperture Mechanism Life Test Plan
30V
22V
36V
200 Cycles
4280 Cycles
-5°C
-35°C
35°C
50°C