TRIO-CINEMA 1 UCB, 2/08/2010
CINEMA Mechanical SystemsDavid Glaser
Mechanical EngineeringSpace Sciences Laboratory
University of California, Berkeley
TRIO-CINEMA 2 UCB, 2/08/2010
Mechanical Systems Agenda
AGENDAExterior Structure (Spacecraft Chassis)Avionics Stack StructureThermal DesignHarnessing Design
Each Section Will Include:OverviewRequirements Design<Test Results if any>Outstanding IssuesDevelopment Plan
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Mechanical Systems - Exterior Structure
Exterior Structure
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External Structure Overview
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Structure Requirements
Level 2 Structure MEC-01 Cubesat 3U Cubesat form factor per Cubesat SpecificationMEC-03 Strength/Vibration Compatible with Cubesat standard and launch
vehicle supporting payload
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Exterior Structure Design
Top and Sides 5052-H32 Al Sheet Metal .048 inches thickEnds ¼ inch 6061 T6 Al
Cutouts for Mass Reduction – (May Be Eliminated for Radiation
Shielding)
3U Corners will be hard anodized per CubeSat Specification
All Dimensions Meet CubeSat Specification
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Exterior Structure Design
Sheet Metal Parts Fastened Together with 4-40 Flathead Screws and PEM nuts
PEM nuts will also be used in some places to fasten components to the chassis wall
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Exterior Structure Design
CubeSat On-Off Switch Requirements
•Remove-Before-Flight Pin Prevents Accidental Power Up
•Deployment Switch(Honeywell hermetically sealed switch)
Closes When P-POD Door Opens
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Exterior Structure Issues
1. Unproven Chassis Design – To our knowledge, no other CubeSats have used this type of chassis and fastening method
2. Possible Interference between PEM nuts and Avionics Stack Boards – TBD when all boards are specified – Screws and holes will be moved if there is interference
3. Should mass reduction cutouts be used or not?
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Exterior Structure Development Plans
• Final Design Changes – February 2010• In-House Fabrication By SSL Machine Shop March-
April 2010• Assemble and Test May 2010• Test Integration with Spacecraft Components
(Summer 2010)• Performance Test In Spacecraft Level Vibration Test
(Fall 2010)
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Mechanical Systems - Exterior Structure
Avionics Structure
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Avionics Structure Overview
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Structure Requirements
Level 2 Structure MEC-05 Avionics Module Provide structural integrity to the avionics board
stackAvionics Module Allows passage of all harnessing between boards
and to and from components external to the stack
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Avionics Structure Design
Board Nominal Component Height
HVPS 1.10 in. (28 mm.)*
MAGIC 0.6 in. (15.24 mm)
Instrument Interface/LVPS 0.6 in. (15.24 mm)
Helium UHF Radio 0.6 in. (15.24 mm)
Clyde 3U Battery 0.98 in. (25 mm)*
Clyde EPS 0.6 in. (15.24 mm)
Processor 0.6 in. (15.24 mm)
Thickness of 7 Boards (.06 in. each) 0.42 in (10.7 mm)
Total Height 5.47 in. (140 mm)
•Available Stack Height: 145 mm•PC-104 Standard Connectors is 0.6 inch Space between boards•Each board is .06 inches thick
*Non-standard board height
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Avionics Structure Design
• Seven PC-104 Boards Connected Via PC-104 Male –Female Standoffs
• Electrical Connections via PC-104 Connector (Except HVPS board)
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Avionics Structure Issues
• Possible interference between components on PC-104 boards – need to map where higher components are on each board
• If height limitation is surpassed, may need to move one or two batteries out of the stack
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Avionics Structure Development Plans
Development• Evaluation of head and foot-room of board
components February-March 2010• In-House Fabrication of Parts by SSL Machine Shop,
March-April 2010• Integration with 7 PC-104 Boards (May? 2010)• Integration with CINEMA Chassis and harnessing
(Summer 2010)• Performance Test In Spacecraft Level Vibration Test
(Fall 2010)
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Mechanical Systems - Exterior Structure
Harnessing
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Harnessing Overview
Make electrical connections between
avionics boards
Make electrical connections between avionics stack and all instruments, and other
components
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Harnessing Requirements
Level 2 Telecom
TEL-03RF Harnessing
Accommodate coax from transmitter/transceiver to splitters, from splitters to patch antennas
Level 3 MAGIC Boom & OB SensorBOM-04 OB MAG
HarnessSupports an 18-conductor (36 AWG magnet wire) shielded harness (captured to OB sensor, Connector on MAGIC board end). Able to withstand the forces from being stored in a coil and deployed several times.
Level 3 STEIN Preamp/ShaperSFE-08 Interface parallel harness to FPGA board (or serial interface using small FPGA
on ADC board - TBD)
Few harnessing requirements have been defined
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Harnessing Design
• Design is mostly incomplete• What has been done:
• MAGIC harness (between MAGIC board and sensor) has been designed and ETU built/tested (more info later)
• Have begun discussions with John Sample on the HVPS board connector and its routing
• Solar Panel to EPS connectors have been defined• Other?
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Harnessing Issues
• No known issues yet
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Harnessing Development Plans
Development• Requirements should be developed – February 2010• As the seven boards in the avionics stack become
available a harnessing scheme will be worked out – February-April 2010
• Recommend meetings to discuss this begin immediately
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Mechanical Systems - Thermal
Thermal Design
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Thermal Overview
Thermal Design Approach is to create a simple model of the heat inputs and outputs through the satellite surface and critical instrument surfaces
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Thermal Requirements
Level 2 Structure MEC-04 Thermal Provide passive thermal design utilizing thermal
finishes on surfaces not covered by solar array. Transfer heat away from power dissipaters to bus (particularly transmitter, which needs ~100g heat sync)
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Thermal Design
• We have only just begun to make a thermal model of the satellite. Early approach: modify spreadsheet made for THEMIS by Dave Pankow
• Model of tumbling spacecraft needed, in a addition to spinning at ecliptic-normal
• Pankow did analysis of deployed magnetometer• Possible surfaces include black anodize, white paint, MLI
• S-Band Transmitter and DC-DC converters both dissipate significant power – will be mounted to chassis wall
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Thermal Analysis Results
• Magnetometer Analysis – D. Pankow
• Combination of white and black surfaces would create best temperature range
• Harness may alter mag temperature by a few degrees
• Stacer boom will be thermally isolated and have a moderate temperature range
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Thermal Analysis Results
• Spacecraft level model – no results yet, but note that upper and lower surfaces of satellite have large areas of aluminum wall exposed – careful choice of surface materials will be needed
• S-Band Transmitter and DC-DC converters both dissipate significant power – will be mounted to chassis walls
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Thermal Issues
We have no thermal specifications for the patch antenna dielectric material (Rogers RT/Duroid 6002). For now we are treating it as a grey painted surface.
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Thermal Development Plans
Lots of work ahead:• Spacecraft level model in Excel will be completed in
early February• Need to include Earth IR emission• Need to include a tumbling mode
• A thermal model and design of STEIN is needed to ensure that the detector remains as cool as possible
• A thermal model of the torque coils is also warranted, as large temperature fluctuations would alter coil resistance and therefore magnetic dipole of the coils
• All thermal models will be reviewed by Chris Smith, SSL thermal engineer
• Thermal Desktop (FEA) models will be created if necessary
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Mechanical Systems – Magnetometer
Magnetometer Mechanical
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Magnetometer Mechanical Overview
Stacer boom(flight spare from FAST
mission)StowedMagnetometer
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Magnetometer Mechanical Requirements
Level 3 MAGIC Boom & OB SensorBOM-01 Length >1mBOM-03 Actuation Actuated by a SMA controlled by the C&DH via a switched
bus voltage power serviceBOM-04 OB MAG Harness Supports an 18-conductor (36 AWG magnet wire) shielded
harness (captured to OB sensor, Connector on MAGIC board end). Able to withstand the forces from being stored in a coil and deployed several times.
BOM-05 OB MAG Mechanical
Supports a 25g OB MAG sensor per the MAGIC ICD
BOM-06 OB MAG Thermal OB sensor to be thermally isolated from stacer and passively thermally controlled by the surface properties between -120 and +50C )TBR)
BOM-07 MAGIC Boom+sensor+harness mass
~160g
BOM-08 Boom Deployment Stow magnetometer and Stacer boom within the space provided; Deploy Magnetometer to 1 m distance with a single, one-shot actuation;
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Magnetometer Mechanical Design
18 Twisted Conductors 36 AWG Magnet Wire with Flight HeritageAracon Braided Jacket – Silver/Nickel
Harness Design
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Magnetometer Mechanical Design
•Spans the width of the CINEMA chassis•Mounted to walls with screws•Mag extends out < 6.5 mm from outer wall
Mag Boom Design TiNi
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Magnetometer Mechanical Design
Kickoff Spring
Potted Sensor in housing
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Magnetometer Mechanical Test Results
1. ETU Harness has been tested for insulation breakdown after extreme bending tests
2. Force Ratio on Pinpuller is 3.3 minimum.3. ETU Mag Boom has been assembled with mock
sensor mass and deployed 11 times• Students have successfully assembled it
4. Twice the release pin experienced binding and pin/bushing interface was redesigned and lubrication added – four consecutive successful deployments since redesign
5. Deployment forces on harness seem to be minimal6. ETU Mass: 210 g (50 g more than requirement)
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Magnetometer Mechanical Test Results
Sample Test
Video
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Magnetometer Mechanical Issues
• Binding of release pin• Will continue to monitor during subsequent tests• Need to define reliability requirement
• Fragility of harness braided jacket • need to develop better handling procedures and reliability
requirement
• Boom length appears to be < 1 m (~0.90 m). MAGIC team has said this is fine as long as they know the exact deployed length
• MAGIC team wants to assure that deployment shock will not exceed instrument limitations
• Thermal design needs to be finalized – surface materials (mentioned earlier in Thermal presentation)
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Magnetometer Mechanical Development Plans
Development• Deployment shock test with STM supplied by MAGIC
team – spring 2010• Possible Vibe Test (Piggyback on RBSP test) Feb-
March 2010• Fabrication of Flight Model Parts – April-May 2010• Integration with CINEMA Chassis (Summer 2010)• Performance Test In Spacecraft Level Vibration and
Thermal Vac Tests (Fall 2010)
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Mechanical Systems - STEIN
STEIN MechanicalDavid Glaser
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STEIN Mechanical Overview
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STEIN Mechanical Requirements
STE-07 STEIN FOV Charged particle FOV 40 degrees by 70 degrees. Two-pi glint free FOV
STE-08 Stray Light Prevent stray light from getting to the detector from any direction, including from the back (sensitive to 1E-6 suns)
STE-09 STEIN Defelectors High voltage surfaces shall be no less than 2 mm away from other surfaces;
STE-10 STEIN Scattered Electrons
Surfaces near the electron trajectories shall be formed to reduce scattered electrons
STE-11 STEIN Mass ~260g for detector head (excludes electronics, HVPS)COL-01 Collimation Provide better than 1E-6 sunlight rejection up to 40 degrees
(TBR) from bore-sight in spin direction
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STEIN Mechanical Design
Baffles and housing interior are blackened
TRIO-CINEMA 46 UCB, 2/08/2010
STEIN Mechanical Design
Attenuator Mechanism is
Modular
STEIN Assembly
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STEIN Mechanical Design
Electrostatic Deflector
30 .002-inch thick BeCu blades sandwiched between .025-inch thick Aluminum clamps
Blades are Cu plated and blackened with Ebanol C
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STEIN Mechanical Test Results
• Mass of ETU Sensor Head: ~250 g (meets requirement)
• Attenuator is easily mounted to and removed from housing
• Deflection plates mount easily into housing• Original deflectors scattered many electrons -
redesigned• No HV arcing was observed in vacuum chamber tests
with original deflectors• New deflectors have been assembled but not yet
tested
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STEIN Mechanical Design
New Electrostatic Deflector Design
30 .002-inch thick BeCu blades sandwiched between .025-inch thick Aluminum clamps
Blades are Cu plated and blackened with Ebanol C
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STEIN Mechanical Design
Electrostatic Deflector
New design is wider to eliminate edge effects
Old Flat Plate Design
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STEIN Mechanical Issues
1. New deflection system needs to be tested in vacuum chamber
2. Need to test blocking of stray visible light
3. End clamps on electrostatic deflectors flex too much – solution is to add third fastener in the middle and/or make parts from stainless steel
4. Should baffles be fastended with epoxy or screws?
5. Thermal requirements/modeling/design needed
6. Assembly procedure of detector board and signal processing boards has not been defined
TRIO-CINEMA 52 UCB, 2/08/2010
STEIN Mechanical Development Plans
Development• New deflection system to be tested - Feb. 2010• Add second side of deflection and test - March 2010• Integrate baffles with epoxy and test light-tightness –
April 2010• Final design changes for flight – March 2010• Fabricate Flight Parts – May 2010• Assemble and Test Flight Model – June-July 2010• Performance Test In Spacecraft Level Vibration Test
(Fall 2010)