Box score: 6 /6 1 - Introduction 2 - Propulsion & V 3 - Attitude Control & instruments 4 - Orbits & Orbit 6 - Power & Mechanisms (Feb. 27) Photovoltaics & Solar panels Maximizing the minimum Batteries and chargers Deployables: Why moving parts dont Common mechanisms Build v. buy v. modify Reliability, testing & terrestrial stuff 7 - Radio & Comms (3/6) 8 - Thermal / Mechanical Design. FEA (3/20) Determination 9 - Reliability (Mar. 3/13) 5 - Launch Vehicles 10 - Digital & Software Cost & scale observations 11 - Project Management Cost / Schedule Piggyback vs. dedicated 12 - Getting Designs Done Mission $ = 3xLaunch $ 13 - Design Presentations The end is near? AeroAstro SPORT
Enginering 176 #6 Review of Last time Actual Attitude Determination & Control Feedback Control Systems description Simple simulation Attitude Strategies The simple life Eight other approaches and variations Disturbance and Control forces (note re CD Design build & test an Attitude Control Syst Design Activity Set Control Team designations Error Algorithm point Mission selections Homework - ACS for mission Sensor + CoDR Enginering 176 #6 Actuator Plant (satellite) Disturbances Design Roadmap You Are Or maybe Here Here Define Mission Concept Propulsion
/ V Comms Solutions & Tradeoffs Attitude Determine & Control Launch Conceptual Design Requirements Ground Station Thermal / Structure Deployables Analysis Info Processing Orbit Top Level Design Parts Specs Materials Fab Enginering 176 #6 Mass Suppliers / Budgets $
Power V Link Bits Iterate Subsystems Detailed Design Final Performance Specs & Cost STP-Sat Requirements (Some) 2.0 System Definition 2.1 Mission Description Requirements & Sys 2.2 Interface Design Definition go 2.2.1 SV-LV Interface together 2.2.2 SC-Experiments Interface 2.2.3 Satellite Operations Center (SOC) Interface 3.0 Requirements 3.1 Performance and Mission Requirements 3.2 Design and Construction 3.2.1 Structure and Mechanisms 3.2.2 Mass Properties
3.2.3 Reliability NB: this 3.2.4 Environmental Conditions is an 18.104.22.168 Design Load Factors 22.214.171.124 SV Frequency Requirements excerpt of the 3.2.5 Electromagnetic Compatibility 3.2.6 Contamination Control TOC 3.2.7 Telemetry, Tracking, and Commanding entire (TT&C) Subsystem docs are 126.96.36.199 Frequency Allocation Highly 188.8.131.52 Commanding (or will structured 184.108.40.206 Tracking and Ephemeris be) on 220.127.116.11 Telemetry outline form is the class 18.104.22.168 Contact Availability clearest and 22.214.171.124 Link Margin and Data Quality FTP site industry standard Enginering 176 #6 126.96.36.199
Encryption For tonight Requirements Doc (mostly done) Mission Requirements System Definition Begin Tech Requirements Launch Strategy (also mostly done) Primary LV and cost The last mile problem Enginering 176 #6 Reading Requirements Doc Sample Power: SMAD 11.4 TLOM 14 Mechanisms: SMAD 11.6 (11.6.8 too) TLOM Thinking What can you build? What can you test? For next Thursday, (March 6) Technical requirements: Preparation: Radios & Comms
SMAD Chapter 13 TLOM Chapters 7,8,9 Systems design / CoDR: create a good looking cartoon set of the spacecraft, orbit and ground segments Get Physical Enginering 176 #6 Create a list of technical requirements - even if it has TBDs in it. (+ revisit mission rqts) Tools selection: Finite element Design and layout Presentation & Graphics Tech Design / Analysis / Suppliers: Structure / Thermal Design and layout Orbit / Launch ACS / Propulsion // $$$ Elements of a CoDR Mission statement Program Plan Design sequence / schedule Prototyping and proof of concept Staffing & facilities (e.g. test) Schedule / overlaps / synergies why do this top level requirements what must you accomplish engineering requirements
A top level "intercept a target" engineering V & G&C Orbit Spacecraft layout Systems: comms, payload, propulsion, power, computing Launch & maneuvering Business Case Organizations (Gvt, Commercial, Military) ID Critical Technologies Enginering 176 #6 Suppliers Costs, lead times Legal, safety, financing -the budget Parts, labor, testing, launch Supplies overhead: salaries, offices, labs, health care, vacation Focus on something Critical subsystem Outstanding attribute Enabling situation - market opportunity Supply: Power: Supply & Demand Sun: 1.34 kW/m2 Solar panels: =~ 20% => ~250W/m2 50% of electricity is heat => At ops. temps,
Radiation=300 W/m2 (courtesy Stephan & Boltzman) Demand 1 Transponder: 200W; 1 DBS XPDR: 2000W On - Board Housekeeping: 100W Iridium / Globalstar class satellite: 500W Micro / nano: 100 W to 1 W Enginering 176 #6 Design Driver: Power Increased Demands for Power: Higher bandwidth (10 x BW = 10 x P) Wide coverage area (5 x area = 5 x P) Increased supply of Power: PV efficiency now 25% may increase to 30% Li-Ion Battery may transition to sulfur sodium (2x mass efficiency, or not) Digital Charge circuits (a few % savings) Sharper antenna patterns: Small GS antenna (1/10th diameter = 100 x P) (a few % savings in power) New array deployment (potential 2x to 100x) Enginering 176 #6 Small v. Big approaches to Power
Small Commercial NiCads (but relatively larger fraction of total mass) Fixed, Body mounted cells (small VA => volume, not W, limit) => passive thermal Big Mil Spec Batteries Large Deployable, articulated solar arrays Large Volume / Area: => Heat matters => heaters / heat pipes / radiators Enginering 176 #6 Power Affects all Engineering Aspects Array & Battery Size Volume, Mass, Cost ($10k/W), Risk Deployables Cost & Risk, CG, Attitude control & perturbations, managing complexity Thermal Larger dissipation => large fluctuations => heat pipes, louvers, structure upgrade High photovoltaics control Other upgrades High cost, tight attitude Power regulation & distribution, charging, demand side devices Enginering 176 #6 Power: Cost Impacts Solar Panel Area Cost of Deployables Pointing requirements Cost / mass of batteries
Tracking array Structural support / mount batteries Thermal issues: G&C disturbance by array - internal dissipation More power -> more data -> - large day / night - more processor cost Heavier spacecraft - higher radio & memory costs - more costly launch Higher launch cost -> Consider GaAs vs. Silicon higher rel. required -> higher parts count and cost A weapon: Power Conservation: - Duty cycle: 75 W Tx @ 20 min per day = 1 W equivalent - Do all you can to cut power on 100% DC items (e.g. processor), - Integrate payload / bus ops: 1 p working 2x as hard is more efficient - Limit downlink: compression, GS antenna gain, optimal modulation, Enginering 176 #6 coding, use L or S band, spacecraft antenna gain / switch, Rechargeable Battery Options Type Mil? Com? Pros Cons Applications E Density W-hr / Kg Heavy Mass not 20 Seal questions a factor Volume constrained
Low capacity Most widely 25 - 30 Mil are large used in space Lead-Acid (gel cells) no Dense, Cheap Wide temp range Ni-Cad Widely available Well characterized Ni - H2 rare NiMH no Li-Ion no Biggest E densityNo space experience Consumer 100 - 150 Fast charge
No space qual electronics More complex charging None Lowest mass No ops in umbra sun synch Lowest cost Max 65% DC most orbits interplanetary Highest reliabilityState saving RAM rqd. Light-side infinite lifetime Enginering 176 #6 Higher E density 5 to 10 x more cycles E to Ni-H2 Lower volume No small sizes individual -> Not yet available multi-cell -> in multi-cell pacs 25 - 40 45 - 60 Consumer electronics 40 - 60 Higher cost, no MIL Battery Charging Global
B DISCHARGE SLOW FAST Tmp A/DSignal Aux PPT Interface Bus Power Power (5V, +/- 12V) aConditioning Sns t t e r y Enginering 176 #6 Water cooler, napkin back & group picnic topics Does the mission really require batteries? Trade vs. e.g. Flash RAM Is Ni-Cad memory real? The real cost of deployables (covered in next section) Battery testing and flight unit substitution Mounting your own cells Real cost of body mount & not sun pointing: - More cells - Shadow questions - Current loops in 3D array - Assembly hassles - Structural shell stiffness requirements multiply photovoltaic 2r
area by: (cylinder) 4 (sphere) 6 (cube) Enginering 176 #6 2 2 r vs.r Do you care? Probably A vs. 6A Design for Solar Power 28 0.70 0.80 0.90 1.00 1.10 Sides + 15% Spherical Sphere 15% end Only endplates normalized plates Satellite normalized Summer Equinox Solstace Winter Spring
Fall Example: Equatorial Earth Oriented Solstace Equinox Enginering 176 #6 Power Budget and Power System Design A 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 B C D E F Initial Deployment Spacecraft Payload Payload Interface Board
Power (W) G H I Max Sun Duty Cycle Avg Pwr (W) Power (W) J Min Sun Duty Cycle Avg Pwr (W) Power (W) Duty Cycle Avg Pwr (W) 20.00 0.00% 0.00 20.00 100.00% 20.00 20.00 100.00% 20.00 2.00 0.00%
0.00 2.00 100.00% 2.00 2.00 100.00% 2.00 Payload Total 0.00 22.00 22.00 Attitude Control System Magnetometer 1.00 100.00% 1.00 1.00 100.00% 1.00 1.00 100.00% 1.00 Sun Sensor (course)
2.00 2.00 100.00% ACS Total Enginering 176 #6 9.10 11.10 2.00 11.10 Potential Paradigm Breakers Advanced deployables Inflatables Flexible photovoltaics Power beaming Cooperative swarms Steerable Phased Arrays Data Compression Enginering 176 #6 LGarde Inflatable Mass total: Astrid Spacecraft 27 kg Mass platform: 22.6 kg HxWxD:
290 x 450 x 450 Max Power 21.7 W Battery: 22 Gates Ni-Cd processor: 80C31 ACS: spin stabilized sun pointing magnetic ctrl. Thermal: Passive Control Downlink: S-band, 131 kb/s Uplink: UHF, 4.8 kb/s Mission $: $1.4M inc. launch Dvt. time: 1 year Enginering 176 #6 Astrid
(Swedish Space Deployables: Why they might Freja: did x 8 Definitely not moving for a long (or too long) time 1-g vs. 0-g (& vacuum) matters Tolerance v. launch loads Vacuum welds, lubricants, galling Creating friction - rigging Static strength, dynamics, resonance Safety inhibits (its physical) Enginering 176 #6 Galileo: didnt x 1 not Flaws, cracks, delamination, vibration loosen/tighten Minute population & test experience (the Buick antenna) Total autonomy High current actuation Statistics - ways to work v. not Common Deployables Satellites (via Marmon rings) Bristol Aerospace, Canada Antennas & Radar Reflectors Booms: gravity gradient & instrument Spar, Canada stacer, astromast Solar Arrays (fixed & tracking) Applied Solar Energy Corp.(ASEC), City of Industry, CA; Programmed Composites, Brea, CA; Composite Optics, Los Angles, CA) Doors (instrument covers)
Mirrors & other optics Rocket stages Marmon Enginering 176 #6 Common Actuators Pyrotechnic bolts and bolt cutters Melting Wires (Israeli Aircraft Industries, Lod, Israel) Hot Wax (not melting wax) Starsys Research, Boulder, CO) Starsys also manufactures hinges for deploybles Memory Metal GSH, Santa Monica, CA Motors and Stepper Motors Carpenter tape hardware stores Sublimation (dural and others) DuPont, 3M Enginering 176 #6 Buicks deployable antenna goes to space (the board game you can play at home) metal-to-metal Replacements: Interfaces: Is it Start: Lighter T Servo How Motor: Minor earDoes Momentum Eliminate T
Shock esting: controls: I, Imax, & contact 12V, temp neg & range? vacuum ground? set /nstop / limit 100,000,000 limproveo Note: gon/off rotation heavy down Subliming EMI, Vibration? effects? / in weight -service; brackets? flexibility? welding fuse? switches GM gets work enough is & ments the Outgassing - angle air cooled
motor? 50,000,000 great; price $179, hous? rebuild matter commence tip Plastics and deployments retail. mass? to Lubricants ? per ing day for 2 years inspect to get bugs out Enginering 176 #6 Two Simple Questions before designing that terrestrial component into your next spacecraft 1) Will it really be the same part? If you change materials, lubricants, loading, mechanical support, housing, coating, wiring, microswitches... It isnt the same part. Almost any terrestrial part will require design mods for its controller, non-standard power supply, cooling, emi protection, surge reduction, structural upgrades 2) How much will it cost to get around the game board?
Specs and shopping: $10k Reengineer with new materials: $50k Lubrication, heat sinking, thermal model: $75k DC/DC converters, surge & EMI suppression: $50k New housing, brackets & structural analysis: $40k Rebuild n units for test, spares, inspection & learning: $50k Test program including 100,000 vacuum ops, + 10 $50k inspections and rebuilds Total - assuming nothing goes wrong (not176 always a good assumption) Enginering #6 $325k Death, Taxes and... Option Pro Con Shell out for the Will Work flight-qualed gizmo Well Defined Price Interesting / educational to see how it was done Popularity with the customer & your troops If you don't change it
If it worked on the Big Mission (?) Which you probably can't afford You'll be tempted to do it yourself (for 1% of the cost) 'till they see the price tag, delivery schedule, power, mass... Modify existing Works on the ground terrestrial device Well tested that meets the needs Cheap Makes you a "dual use" hero So what Ditto But high cost to modify and test First prize: Career as a bureaucrat Roll your own Appeals to our Pioneer Spirit Arrows in back No big company overhead Prodigious consumer of engineering hou Meets all mission requirements On paper, anyway If it gets done in time for the launch Enginering 176 #6 Something the whole space community can benefit from They'll find reasons to ignore you They are requirements, not supply, driv (or they are politically / business optimize What Deployables Really Cost Example: 4 deployable solar panels
(cost compared with 1 large non Fab of 4 discrete paddles + 1 spare: deployable panel) $40k 4 highly reliable actuators (hot wax) $150k 4 highly overbuilt hinges & brackets $60k Engineering: design, thermal, structural and dynamic analyses $50k Testing fixtures and test labor $50k Total out of pocket increased cost: $350k Harder to quantify costs: - risk of deployment failure - CG complications on G&C impact - risk of premature deployment - Safety qualification - design review scrutiny - Vigilance during integration / test - Murphy: one paddle broken in test costs $20k to replace in Enginering 176 #6 Getting Beyond Deployables Eliminate the need for deployables: Larger launch envelope may be cheaper (and its more reliable) Upgrade to Ga-As photovoltaics
Increase testing & trimming to reduce stray fields (e.g. for magnetometers) Use stuffing - things that deploy when other things deploy Reduce Requirements Limit power budget to achievable with fixed array Lower duty cycles in poor orbit seasons (i.e. dont design for worst case) Lower accuracy (e.g. for magnetometers) Replace GG boom with magnet or momentum wheel Open instrument doors manually just before launch Break mission into several smaller missions If all else fails... Design as if the deployables you cant eliminate might not work (graceful degradation) Purchase insurance Deployables must be testable at 1-g, 1 atm, room temp... Enginering 176 #6 Deployables Checklist Withstand temperature, vibration, storage time, vacuum, radiation? Acceptable EMI, RFI, Magnetic moment, linear / angular momentum? Outgassing materials, especially plastics and lubricants but also wire insulation and other sub-parts? Vacuum welding possible? Sufficient cooling and lubrication without air and natural convection? Internal electronics: rad hard? Bit flip and latchup protected? Totally autonomous and reliable? Document and discuss all anomalies! Testable on earth? Safety: fire, fracture, pressure, circuit protection, inadvertent deployment? Power: surge, peak, voltage requirement(s)? Design and design mods review? Test program review? Large margins in design? Not compromised in ground fiddling? Schedule and cost margin? Failure tolerance - it still may not work... Enginering 176 #6
Deployables Spec Performance Applied torque or force, speed, accuracy, preload, angular momentum (eg mirror) Weight / Power Allocations from system design spec Envelope Mech. & electrical interface, dimensions & interfaces bolt patterns, interface regions... EnvironmentsNumber of cycles, duration exposure to environments -> parts, materials, lubes Lifetime (op/non) exposure Structure # operating cycles, duration Strength, fatigue life, stiffness Reliability Allocation from system rel. spec - may drive specific approach & redundancy Enginering 176 #6 Freja Freja Facts: 8 science instruments; deployed 6 wire booms (L=1 to 15 meters) deployed 1m and 2m fixed boom spacecraft separation: 4 pyro bolts plus standard marmon ring; Orbit insertion:2 Thiokol Star engines Start: 8/87; shipped to Gobi Desert 8/92 #6 Enginering High Q176 passive thermal design;
Magnetospheric research Launched October, 1992 214 kg, 2.2 m diameter Development cost: $23M Freja (Swedish Space Corp) Galileo Launched Oct. 89 Mass: 2.5 Mg NASA JPL Galileo HGA Info: Development cost about $1.5B HGA loss dropped data rate by 104 Failure caused by loss of lubricant, probably during several cross-country truck shipments (note similarity to Pegasus failure during HETE / SAC-B launch Deployable failure caused by poor lubrication - or by misjudgement of environment? Enginering 176 #6 QuickTime and a Cinepak decompressor are needed to see this picture. Enginering 176 #6 Terrestrial Stuff that works in Space Electronic Components: ICs, transistors, resistors, capaciters (beware of electrolytic), relays
Electronic devices Vivitar photo strobe, timers, DC/DC Converters, many sensors Ni-Cad batteries with selection and test. Li-ion are also being flown Carpenter Tape has never failed Laptop computers, calculators in Shuttle environment Stacer Booms but rebuilt with new materials - imperfect performance on orbit Hard disc in enclosure - but why bother? People, monkeys, dogs, algae, bees... Enginering 176 #6
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