spacecraft structures

Spacecraft Structures

Heather ReedMechanical Engineering Manager

Laboratory for Atmospheric and Space Structures

reed@lasp.colorado.edu

What is a structure?

Why does a spacecraft need a structure?

PRIMARY or Secondary?

3 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

Lifecycle of a Structure

REQUIREMENTS(NEEDS)

DESIGN

ANALYSIS

BUILD

TEST

INTEGRATION

STUDENT NITRIC OXIDE EXPLORER (SNOE)

4 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

REQUIREMENTS

• What does this spacecraft structure need to do?

• Accessibility• Lift points

– Vibe– Acoustic– Shock

» Thermal» Radiation

ROCKET LAUNCH

GROUNDTESTING

ON-ORBITCONDITIO

NS

5 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

DESIGN – What shape will it be?

• SNOE was a “spinner”

6 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

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 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

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 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

SPACECRAFT

ROCKETNOSECONE

ROCKET SECONDARYSTAGE

DESIGN – Will it fit?

• Solid Modeling– Static or Dynamic

9 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

Solid Modeling - SolidWorks

10 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

ANALYSIS - Modal Simulation Results

Mode 2 – 821 Hz – Mode shape plotRocking in the Y-direction

Mode 6 – 1270 Hz – Mode shape plotRocking in the X-direction

• 821 Hz: First predicted high mass participation mode.

• 741 Hz: Lowest frequency mode is a local connector bracket mode.

• Z-axis has very little mass participation below 2000 Hz.

• Two principal mode shapes shown below:

11 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

BUILDING IT – Your best laid plans

• Fabrication – Do 2 planes meet perfectly?

• Assembly – How clean is clean?

12 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

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 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

TESTING – Vibration Testing

• Mass model testing – Good practice• Test sensors - Accelerometers

LARGE SPEAKER “VIBE TABLE”

AT BALL AEROSPACE

SNOE SPACECRAFT

14 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

Vibration Test Specification

15 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

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 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

INTEGRATION to the Pegasus

17 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

Secondary Structure – Solar Arrays

18 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

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 / SSLLPW/Extreme Ultra-Violet (LPW-EUV) – LASP

LPW-EUV

20 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

Testing

• Engineering 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• Torque margins• Spring force

– Light leak testing

21 Nov 8th, 2011 Spacecraft Structures Heather Reed, ME Manager

Aperture Mechanism Life Test Plan

-40

-20

0

20

40

60

Tem

p (d

egC)

30V

22V30V36V

22V30V36V

22V30V36V

30V

200 Cycles

4280 Cycles

-5°C

-35°C

35°C

50°C