THEMIS Instrument PDRRob Duck 1 UCB, October 15-16, 2003 EFI Axial Booms (AXB) Preliminary Design Review Rob Duck Mechanical Engineering Department and Space Sciences Laboratory Univ. of Calif., Berkeley

THEMIS Instrument PDRRob Duck 2 UCB, October 15-16, 2003 Requirements & Specifications THEMIS Mission Design Requirements Axial boom designed in accordance with the THEMIS Product Assurance Implementation Plan (PAIP) Mechanical design and test environments as outlined in Mechanical-Verification-Spec-1c by Swales Aerospace Deployed axial boom shall be repeatable and stable to and L/L = 1% Axial boom shall be designed to be deployed between 0 and 25 RPM Axial boom deployed stiffness shall be greater than 0.75 Hz Axial sensor baseline will be ~10 m, tip to tip

THEMIS Instrument PDRRob Duck 3 UCB, October 15-16, 2003 Requirements & Specifications Mechanical Design Objectives Axial boom shall be modular and removable from probe with minimal probe disassembly Axial boom test and safe plug shall be externally accessible to probe Each individual boom shall have a single point of actuation Axial boom design shall be based on heritage designs from previous launches Mass 2 Kg per boom Deployment execution is critical Proper stowing of wire cable One time deployment Full boom extension

THEMIS Instrument PDRRob Duck 4 UCB, October 15-16, 2003 Axial Boom Overview AXB are integral part of THEMIS probe Primary probe structure provided by Swales Aerospace AXB located along center axis of probe AXB deployment through top and bottom decks of probe. Test & Safe Plug Lower Deck Mount Composite Tube Antennae Mount (TBD by Swales) AXB relative to THEMIS ProbeInternal View AXB Assembly THEMIS Probe Upper Deck Mount Upper AXB Lower AXB AXB Housing

THEMIS Instrument PDRRob Duck 5 UCB, October 15-16, 2003 Design Heritage AXB Base Design has flown before POLAR FAST UCB Heritage Test data from previous flights Design engineers still at UCB Using the same vendors Consistent assembly and test procedures AXB Heritage Design Double boom deployment Stacer booms Double cantilever design Deploy Assist Device

THEMIS Instrument PDRRob Duck 6 UCB, October 15-16, 2003 Axial Boom General Assembly Whip Canister (Whip Sensor Inside) Double Deploy Assist Device (DDAD) Tube Mounting Brackets Preamp Cable Bobbin Stacer Canister (Stacer inside) INDIVIDUAL BOOM IN STOWED CONFIGURATION SMA/Ball détente Actuator Whip Doors DDAD Doors STACER Design Modifications Stacer length Double deploy assist device SMA/Ball détente actuation Whip sensor Roller Nozzles Whip Posts

THEMIS Instrument PDRRob Duck 7 UCB, October 15-16, 2003 Theory of Operation Integration & Loading Whip Sensor is loaded into whip canister Whip canister is locked to the preamp by the whip clamp Stacer is loaded into stacer canister, DDAD doors hold the DDAD, and whip doors hold the whip canister Removable stacer pin is inserted through stacer tip piece, which locks the stacer, DDAD, and Whip canister to the boom assembly Cable is spooled around the cable bobbin Ball détente mechanism is clamped to the stacer tip piece Stacer pin and whip clamp are removed Boom is loaded into housing Deployment SMA wire is actuated and ball détente mechanism is engaged Stacer tip piece is released DDAD extends and initiates stacer deployment DDAD separation opens whip doors, initiating whip sensor deployment Science Ops Deployed boom configuration unchanged

THEMIS Instrument PDRRob Duck 8 UCB, October 15-16, 2003 Whip Sensor Theory of Operation Deployed Properties Whip sensor deployed length: 40 inches Stacer deployed length: 150 inches Option to change length Stacer Stacer Pin Ball Détente Mechanism Cable Bobbin with Cable DDAD DDAD Doors SMA Actuator Stowed BoomDeployed DDAD 4 4 Stacer Cansiter Stacer Tip Piece Whip Canister Whip Doors Roller Nozzle Deployed Boom Deployed Whip Sensor

THEMIS Instrument PDRRob Duck 9 UCB, October 15-16, 2003 Goals 1.Initiate Stacer deployment. 2.Provide double cantilever design at deploy. 3.Maintain minimal boom length while stowed. 4.Single locking contact point. Design 1.Two stage nested spring push rod. 2.Roller nozzle for beam support. 3.Double doors to stow Whip and Main Stacer. Theory of Operation 1.Stacer tip piece is released. 2.Double spring extends roller nozzles. 3.Roller nozzle pulls stacer from canister 4.Stacer deploys. 5.Whip doors open as roller nozzles separate. 6.Whip deploys. 7.Roller nozzles maintain contact on stacer. Double Deploy Assist Mechanism STOWED DDADDEPLOYED DDADDDAD PUSH ROD ROLLER NOZZLE STOWED ROLLER NOZZLE DEPLOYED Roller Nozzle Locking Contact Face Whip Doors DDAD Doors Stacer direction

THEMIS Instrument PDRRob Duck 10 UCB, October 15-16, 2003 Goals 1.Single actuation point. 2.Safe reload operation for testing. 3.Minimal activation stroke. 4.Minimal activation force. Theory of Operation 1.Applied current contracts SMA wire. 2.SMA wire pulls lever up. 3.Lever pulls deploy pin down. 4.Lower ball detent drops into cavity and release spring rod. 5.Spring extends and pulls locking sleeve down. 6.Upper ball detent drops into cavity. 7.Stacer pin is released and stacer deploys. Axial Boom Deploy Mechanism STOWED CONFIGURATION SECTION VIEW DEPLOYED CONFIGURATION SECTION VIEW Stacer Tip Piece Cable Bobbin Locking Sleeve Spring Rod Lever Deploy Pin Upper Ball Detent SMA Wire Lower Ball Detent

THEMIS Instrument PDRRob Duck 11 UCB, October 15-16, 2003 Assembly & Materials Standard Flight Materials AL 6061 T6 SST 440 Elgiloy PEEK M55J Graphite Composite Standard Flight Coatings DAG-213 DAG-154 TYPE 3 Hard Anodize Long Lead Items Stacer – Ordered Multi-conductor wire

THEMIS Instrument PDRRob Duck 12 UCB, October 15-16, 2003 Electrical Connections Boom Connectors 1 connector per boom Located at base of boom SMA actuator cable Preamp sensor multi-conductor wire Test & Safe Connector External to boom, located on top deck of probe AC test Safe - Deploy deactivation

THEMIS Instrument PDRRob Duck 13 UCB, October 15-16, 2003 Mass & Power List Mass Target & Actual MASS –Target –2 Kg per Boom including Housing –Actual Housing1.70 lbs0.772 kg Upper Boom3.58 lbs1.625 kg Lower Boom3.58 lbs1.625 kg Total8.86 lbs4.022 kg POWER –1 AMP

THEMIS Instrument PDRRob Duck 14 UCB, October 15-16, 2003 Thermal - AXB Heat Transfer Power Dissipation 80 mW dissipated at preamp, irrelevant to bus temperatures Essentially inert hunks of metal after deployment Conduction Top Deck reaches –93 °C in long eclipse AXBs are a heat leaks for the bottom deck so they are isolated with 1/8 inch G10 spacers. Radiation All surfaces covered with low ε VDA tape or blankets Black body open end of the tube dominates the heat leak

THEMIS Instrument PDRRob Duck 15 UCB, October 15-16, 2003 Thermal - AXB Temperature Limits Steady state predictions from UCB based on top and bottom deck temperatures from Swales Cold prediction from cold orbit, not long eclipse Hot prediction from hottest orbit and attitude Will not deploy in extreme cold case Better predictions await more complete instrument thermal models Deployment (°C) Predictions (°C) Margin (°C) ColdHotColdHot

THEMIS Instrument PDRRob Duck 16 UCB, October 15-16, 2003 Thermal - AXB Temperature Monitoring and Control Modified Interface Monitoring None required at this time Instrument Monitoring IDPU will process additional thermistors if needed Heaters No operational heaters are required No survival heaters needed after deployment Unlikely to need deployment heaters

THEMIS Instrument PDRRob Duck 17 UCB, October 15-16, 2003 Engineering Model Objectives Engineering test unit designs are critical Boom length repeatability DDAD stiffness and length Actuation reliability Boom reloading DDAD roller nozzle design

THEMIS Instrument PDRRob Duck 18 UCB, October 15-16, 2003 Axial Boom General Assembly Axial Boom Installation process Goal to allow easy removal of boom without probe disassembly Process 1.Lower mount ears aligned with upper deck cutout. 2.Boom inserted through upper deck. 3.Boom rotated to line up bolt pattern. 4.Boom bolted with 8-32 screws