1 Structure (STR) Subsystem Overview Jonah White – STR Co-Lead

Structure Overview Main Satellite Structure Functions –Provide housing for all components –Protect sensitive components from harmful launch/space conditions –Electrically conductive to prevent plasma charging Component Box Functions –Secures electrical components to main structure –Provides electrical magnetic interference (EMI) containment –Allows for better thermal control 2 Component Boxes Battery Box

3 Structure Requirements STR-1Must fit within allowable static envelope (60 X 60 X 50 cm) M-1TestUnverified STR-2Must have a fundamental frequency above 100 Hz M-1Analysis/TestUnverified STR-3Must be able to withstand 20 g’s of force in all directions M-1AnalysisUnverified STR-4Must meet a safety factor of 2.0 yield and 2.6 ultimate M-1AnalysisUnverified STR-5 Must meet an operating torque margin of 1.0(test) and 2.0(analysis) M-1Analysis/TestUnverified STR-6 Must survive a random vibration test at 0.25 gRMS from 20 to 2000 Hz M-1Test(ARFL)Unverified STR-7Must survive a sine burst test at 1.2 times the limit loads M-1Test(ARFL)Unverified STR-8 Must survive a shock spectrum max of Hz and ASD levels of 3500g M-1Test(ARFL)Unverified STR-9Must have a mass not exceeding kg M-1TestUnverified STR-10 Must have a center of gravity of less than cm from the NS-5 centerline M-1Analysis/TestUnverified STR-11 Must have a center of gravity of less than cm above the SIP M-1Analysis/TestUnverified STR-12Must provide vent holes in component boxes M-1TestUnverified

Structure Requirements STR-13 Must provide venting analysis for depressurization and repressurization M-1AnalysisUnverified STR-14 Must not use pressure vessels and pressurized components as defined in NASA-STD-5003 M-1TestUnverified STR-15Must use at least #10 screws for all structurally critical components M-1TestUnverified STR-16Must use at least #8 screws for all component boxes M-1TestUnverified STR-17 Must provide a lightband interface in accordance with PSC Rev A M-1TestUnverified STR-18 Must use ¼-28 socket head cap screws for lightband interface fastener holes M-1TestUnverified STR-19 Must use ¼-28 threaded self-locking inserts if locking helicoils are used for backout prevention M-1TestUnverified STR-20 Must have a test-verified flatness of inches per inch over the NSS envelope at the SIP M-1TestUnverified STR-21 Must provide thermal analysis to validate adequate thermal protection during all mission phases M-1TestUnverified STR-22Must provide a list of all payload external surface properties M-1TestUnverified STR-23Must provide metal component boxes for Goldeneye’s hardware GS-1TestUnverified STR-24 Must have an electrically conductive coating on metal component boxes GS-1TestUnverified 4

Design Strategy Make sure strategic requirements are fulfilled first –Static envelope (60 x 60 x 50 cm) –Fundamental frequency (greater than 100 Hz) – 20 g’s loading –C.G. (0.635 cm from centerline) –Mass limit (50 Kg) Machine-ability –All parts can be machined –Advice from experienced machinists Keep it simple!!! –Ease of assembly (~30 min for prototype) –Structural design is not the mission Use NASA preferred parts if possible Stick to what has been proven 5

Satellite Structure 6 GPS Direct Signal Antennas Solar Panels Lightband Interface High Gain Antenna

Satellite Side Panel 7 Each Side Panel Consists Of –Aluminum panel with isogrid pattern –11 machined brackets Attached with #10 socket cap screws –Torque coil mounts Attached with #8 socket cap screws Torque Coil

Satellite Side Panel Assembly –Brackets tapped –Locking helicoils used for back-out prevention –Torque coil mounts attached using lock nuts –All pieces assembled to side panel before panel attached to main structure 8

Satellite Side Panel Side Panels –Machined aluminum 6061-T6 –0.635 cm thick (1/4 inch) –Alodined –Isogrid pattern NASA-CR , Rev. A, Isogrid Design Handbook Use 60˚ equilateral triangles 0.2 cm minimum triangle side thickness Nodes no more than 7 cm apart Rounds at all corners –#10 screw holes tapped to incorporate brackets and solar panels –#8 screw holes to attach component boxes 9

Satellite Bracket Brackets –Machined aluminum 6061-T6 –90˚ angle –0.32 cm (~1/8 inch) round –#10 screw holes tapped thru (1.5 x diameter of screw) JSC 23642, Rev. D, JSC Fastener Integrity Testing Program –Locking helicoils and spring lock washers for backout prevention 10

Torque Coil Mounts –Machined aluminum 6061-T6 –2 piece design –Assembled with #8 button head socket cap screws –Faces are 0.3 cm thick (~1/8in) 11

Satellite Top Panel Satellite Top Panel Consists of –Aluminum panel with isogrid pattern –Torque coil Attached with #8 socket cap screws –Battery component box Attached with #8 socket cap screws 12

Satellite Top Panel Top Panel Consists of –Machined aluminum 6061-T6 –0.635 cm thick (1/4 inch) –Alodined –Isogrid pattern –#10 screw holes tapped to incorporate brackets and attach solar panels –#8 screw holes to attach battery box 13

Satellite Bottom Panel Bottom Panel –Machined aluminum 6061-T6 –0.635 cm thick (1/4 inch) –Alodined –Minimal isogriding –Hole cut-out to accommodate high gain antenna mounting –Lightband interface –#10 screw holes tapped to incorporate brackets 14

Battery Box –3 piece box machined aluminum design –Stand-offs to accommodate solar panel screws –#8 screws for assembly –Utilize viton gasket for EMI containment 15

Battery Box Machined aluminum 0.3 cm (1/8 inch) thick Coatings –Outside box alodined –Inside box anodized 16

Component Boxes –3 piece box design –Machined aluminum –Stand-offs to accommodate solar panel screws –#8 screws for assembly –Utilize viton gasket for EMI containment –Alodined 17

Mass Breakdown 18 Total mass – 38.8 Kg

Structures Schedule 19

Questions? 20