Magnetometer Booms (MAGS) Mission Preliminary Design Review Hari Dharan Space Sciences Laboratory

1. Magnetometer Booms (MAGS) • Mission Preliminary Design Review • Hari Dharan • Space Sciences Laboratory • University of California at Berkeley

2. Mission Requirements

3. Mission Requirements

4. Boom Requirements

5. Heritage • Design construction, and operation based on FAST and Lunar Prospector magnetometer booms • Requirements • All requirements allocated • System Performance Budget, Error Budget • Addressed via IN.BOOM requirements in coordination with Swales mechanical group • Margins • Torque ratio of >3:1 maintained in all moving parts design, to be verified in test program • Analytical SF >1.4 x limit loads for ultimate failure modes for metallic components, >2.0 for composite components • Descope Plans • SCM not necessary for minimum science

6. Mass budget 15% 27% • ICDs substantially complete (available for review) • Resolution of TBDs in works – complete by 11/30

7. Overview Elbow Latch SCM Base Hinge (similar to FGM Base Hinge) • Components of Mag Booms Carbon-fiber tubes FGM: 1.9m SCM: 1m FGM Base Hinge/ Frangibolt SCM Frangibolt

8. Overview • Deployment of Mag Booms • SCM and FGM frangibolts fire. • Deployment springs at base hinges deploy booms. • Additional kickoff spring at FGM elbow

9. Deployment Simulation • Simulated in MATLAB • Calculates accelerations of each link - based on three link pendulum model • Includes latching events, deployment spring forces, and kickoff spring forces • Inputs: Spin rate, Spring rates, Moments of inertia, Initial position • Outputs: Kinetic Energy, Latch Time, Deployment animation

10. Proposed Design - Frangibolts • TiNi Aerospace’s FC2-16-31SR2, 2200N, 25W Frangibolt • Reliable, flight heritage (HESSI, Mars Express, Cloudsat, Coriolis, etc.) • Kickoff spring to ensure release from caging tower Frangibolt Implementation

11. Proposed Design - Elbow • Features • Compact and simple design. • Disc springs allow for high force low displacement action • Design of shear support with kickoff springs eliminates sticking • Allows for zero RPM deployment Elbow Latch

12. Proposed Design – Base Hinge • Base Hinge Overview Features • Energy absorption • Zero Kinetic Energy Latching Deployment Spring Latch Pin Spring Large Energy Absorption Spring Stowed Deployed

13. Proposed Design – Base Hinge FGM/SCM Base Hinge Deployment/Latch Sequence: Animation

14. Other design considerations • Other considerations • ETU testing to verify friction in shaft/clevis and stop rings. • ETU testing to verify reliability and repeatability in deployment including thermal considerations. • Spin axis/boom bias • Booms are given slight (2-3° TBV) bias out of spin plane • Kinematically defined end position despite unknown satellite spin axis • Angles are exaggerated to illustrate principle

15. Tube Design – NASTRAN Modal Analysis • Frequency Spec • Mag. Boom stowed stiffness shall be greater than 100 Hz • Mag. Boom deployed stiffness shall be greater than 0.75 Hz • Current Design • Frequency spec is met by current tube layup • More detailed NASTRAN work will follow. • ETU tube vibration test to verify will be performed in January. 1st mode shape of stowed FGM outer boom. 1st mode shape of deployed FGM boom.

16. Tube Design – Deployment Stresses • Deployment stress in the tube was estimated assuming all the kinetic energy was converted to strain energy in the tube at latching. (Maximum kinetic energy at 15 rpm: SCM base hinge, ~2J, FGM base hinge, ~1J, FGM elbow hinge, ~0.3J) • Tube was treated as end loaded, cantilever. • For the nominal case(SCM ~2J, FGM~1J), the stresses in the FGM and SCM tubes were below their compressive and tensile strengths. • Detailed NASTRAN stress analysis will be performed.

17. Tube Design • Tube/Layup Design considerations • Frequency spec. • Deployment stresses. • Mass allocations. • Fabrication Handling. • Designed Lay-up • [(0/90)T300 / ((0)M60J)5]s • T300 = high-strength carbon fiber/epoxy woven (0.005”/ply), M60J = high-modulus carbon fiber/epoxy tape (0.002”/ply)(to be replaced with lower cost M55J with 5% less modulus) • Tube Design • Thickness = 0.030 in. • Inside diameter = 1.250 in. • Effective Modulus = 33 x 106 psi (230 GPa) • Mass per unit length = 3.2 g/in (1.26 g/cm)

18. Thermal Considerations • Thermal expansion effects on dimensional stability of mag booms are expected to be small due to low CTE of carbon fiber tube (expected to be -0.5 ppm/K; Al = 24.7 ppm/K) • Thermal stress generation may necessitate Ti-6Al-4V for lower thermal stress. Prototype carbon fiber/Al and Ti joint configurations will be thermal cycled between qual temperature limits and proof tested to evaluate effect of thermal cycling on bond strength. • Thermal Analysis (detailed to be performed on final design configuration using NASTRAN) • CTE stability in deployed configuration (thermal soak) • Thermal stresses and displacements (between M55J deck and base brackets and Frangibolt housing, and between carbon fiber tube and end fittings) • Thermal gradient effects • Tolerance effects • CTE stability

19. Fabrication and Assembly Plan • Tube Fabrication • Bldg 151,Richmond Research Center (RRC). • Table rolling process to produce tubes • Fiber alignment • Use of space qualified pre-preg • Rapid production • Quick tool change Table Roller Shrink Tape Wrapper Oven Mandrel Puller

20. Fabrication and Assembly Plan • Bonding of Tubes • Bonding fixture has bolt holes to match location of deck inserts. (Bolt hole pattern will be kept consistent between UCB and Swales via a template) • Hinges will be bolted to bonding fixture and tubes bonded. • Bldg 151, RRC. • Assembly of Hinges, Harness, and Frangibolts • Harness will be routed through booms. Frangibolts and their assembly will be attached to the mag booms. • Facility in SSL.

21. Test Plan • Test Plan • Tube testing • 1.25 x Limit Load proof test of each tube Joint testing • 1.25 x Limit Load proof test adhesive bond between tube, end fittings and hinges. • ETU testing • Vibration test with instrument mass simulators. Response to be delivered to FGM/SCM team for flight mag testing. • Offloaded deployments on engineering model with mass simulators. • Verify deployment margins with reduced load deployments. • Flight Unit testing • Testing (Offloaded deployment, vibration, thermal vacuum with hot and cold first motion tests, offloaded deployment. All with mag mass dummies). • First motion test on S/C to verify mounting.

22. Schedule • Design and Analysis • Ongoing. Preparing for CDR in Mar/Apr 2004. • Fabrication and Assembly • Fabrication of ETU Mag Booms: 11/20/03 to 1/20/04 • Fabrication of Flight Mag Booms: 3/30/04 to 6/14/04. • Assembly of Flight Mag Booms: 6/15/04 to 9/13/04. • Testing • Tube testing : during ETU and Flight tube fabrication • Joint testing : during ETU and Flight Unit assembly • ETU testing (week of 2/23/04) • Flight Unit testing : 8/10/04 to 9/28/04.