Spacecraft Structures Heather Reed Mechanical Engineering Manager Laboratory for Atmospheric and Space Structures reed@lasp.colorado.edu

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

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

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

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

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

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)

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

Solid Modeling - SolidWorks

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

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

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

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

Vibration Test Specification

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

INTEGRATION to the Pegasus

Secondary Structure – Solar Arrays

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

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

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

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