TRIO-CINEMA 1 UCB, 2/08/2010 CINEMA Mechanical Systems David Glaser Mechanical Engineering Space...

TRIO-CINEMA 1 UCB, 2/08/2010

CINEMA Mechanical SystemsDavid Glaser

Mechanical EngineeringSpace Sciences Laboratory

University of California, Berkeley


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


Mechanical Systems - Exterior Structure

Exterior Structure


External Structure Overview


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


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



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



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


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?


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)



Avionics Structure


Avionics Structure Overview


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


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


Avionics Structure Design

• Seven PC-104 Boards Connected Via PC-104 Male –Female Standoffs

• Electrical Connections via PC-104 Connector (Except HVPS board)


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


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)



Harnessing


Harnessing Overview

Make electrical connections between

avionics boards

Make electrical connections between avionics stack and all instruments, and other

components


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


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?


Harnessing Issues

• No known issues yet


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


Mechanical Systems - Thermal

Thermal Design


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


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)


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


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


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


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.


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


Mechanical Systems – Magnetometer

Magnetometer Mechanical


Magnetometer Mechanical Overview

Stacer boom(flight spare from FAST

mission)StowedMagnetometer


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;


Magnetometer Mechanical Design

18 Twisted Conductors 36 AWG Magnet Wire with Flight HeritageAracon Braided Jacket – Silver/Nickel

Harness 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



Kickoff Spring

Potted Sensor in housing


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)


Magnetometer Mechanical Test Results

Sample Test

Video


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)


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)


Mechanical Systems - STEIN

STEIN MechanicalDavid Glaser


STEIN Mechanical Overview


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


STEIN Mechanical Design

Baffles and housing interior are blackened



Attenuator Mechanism is

Modular

STEIN Assembly



Electrostatic Deflector

30 .002-inch thick BeCu blades sandwiched between .025-inch thick Aluminum clamps

Blades are Cu plated and blackened with Ebanol C


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



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



Electrostatic Deflector

New design is wider to eliminate edge effects

Old Flat Plate Design


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


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)

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