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Box score: 6 / 6

1 - Introduction 2 - Propulsion & ∆V 3 - Attitude Control & instruments 4 - Orbits & Orbit Determination 5 - Launch Vehicles Cost & scale observations Piggyback vs. dedicated Mission $ = 3xLaunch $ The end is near? AeroAstro SPORT. 6 - Power & Mechanisms Photovoltaics & Solar panels

stuart-greene
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Box score: 6 / 6

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  1. 1 - Introduction 2 - Propulsion & ∆V 3 - Attitude Control & instruments 4 - Orbits & Orbit Determination 5 - Launch Vehicles Cost & scale observations Piggyback vs. dedicated Mission $ = 3xLaunch $ The end is near? AeroAstro SPORT 6 - Power & Mechanisms Photovoltaics & Solar panels Maximizing the minimum Batteries and chargers Deployables: Why moving parts don’t Common mechanisms Build v. buy v. modify Reliability, testing & terrestrial stuff 7 - Radio & Comms 8 - Thermal / Mechanical Design. FEA 9 - Reliability 10 - Digital & Software 11 - Project Management Cost / Schedule 12 - Getting Designs Done 13 - Design Presentations Box score: 6 / 6 Enginering 176 #6

  2. A large number of small monthly payouts ------ the word from our sponsor: $$$ …adds up to a lot of negative equity ------ …and even more with foregone interest included ------ Enginering 176 #6

  3. Attitude Determine & Control Propulsion / ∆V GroundStation Thermal / Structure Deployables Comms Launch Info Processing Orbit Mass $ Power ∆V Link Bits Design Roadmap Or maybe Here You Are Here Define Mission Concept Solutions & Tradeoffs Requirements ConceptualDesign Analysis Top Level Design PartsSpecs Suppliers / Budgets MaterialsFab Iterate Subsystems Final Performance Specs & Cost Detailed Design Enginering 176 #6

  4. (Some) STP-Sat Requirements 2.0System Definition 2.1 Mission Description 2.2 Interface Design 2.2.1SV-LV Interface 2.2.2SC-Experiments Interface 2.2.3Satellite Operations Center (SOC) Interface 3.0Requirements 3.1 Performance and Mission Requirements 3.2 Design and Construction 3.2.1Structure and Mechanisms 3.2.2Mass Properties 3.2.3Reliability 3.2.4Environmental Conditions 3.2.4.1 Design Load Factors 3.2.4.2 SV Frequency Requirements 3.2.5Electromagnetic Compatibility 3.2.6Contamination Control 3.2.7Telemetry, Tracking, and Commanding (TT&C) Subsystem 3.2.7.1 Frequency Allocation 3.2.7.2 Commanding 3.2.7.3 Tracking and Ephemeris 3.2.7.4 Telemetry 3.2.7.5 Contact Availability 3.2.7.6 Link Margin and Data Quality 3.2.7.7 Encryption Requirements & Sys Definition go together NB: this is an excerpt of the TOC - the entire doc is (or will be) on the class FTP site Highly structured outline form is clearest and industry standard Enginering 176 #6

  5. Single vs. Two Stage TwoSTO: S-1∆V(s)=5000m/s (2 stages, equal ∆V) S-2 mass: 505 kg S-2 structure: 150 kg S-2 PMF: 20% Assumptions: • R = M(i)/M(f) = 10 • ∆V required: 10 km/s• Payload = 100 kg• Payload =10% Mf TwoSTO: S-2 ∆V(s)=5000m/s S-1 mass: 2595 kg S-1 structure: 770 kg S-2 PayMF: 20% SSTO: 100 kg payload ∆V = gIspln(R): Isp = 420 (H2 / O2) Launch mass: 12,500 kg Structure = 1000 kg => R = 12.5 Stage payload Mass Fraction: 0.8% TwoSTO: ∑ ∆V =10000m/s Total Mass: 3100 kg Total PayMF: 3.2% Enginering 176 #6

  6. 1 2 3 4 5 6 Orbital Insertion Enginering 176 #6

  7. Optics Lesson #1: Pinhole Camera Spot diameter = 0.01 rad x L =~ 400km (where L = 40,000 km = GEO altitude) Spot area =~ 1011 m2 => every m2 of mirror yields 10-11 sun brightness: 1km2 mirror yields 10-5 sun brightness = 10 x lunar illumination 0.01 radian L = 40,000,000 m From 400 km LEO every m2 of mirror yields 10-7 sun brightness: 10x10m yields 10-5 sun brightness = 10 x lunar illumination over diameter = 4km Diffraction limit = lL/D = 10-6 x 4x107 / 1 = 40 meters - not limiting Enginering 176 #6

  8. Requirements Doc Mission Requirements System Definition Begin Tech Requirements Launch Strategy Primary LV and cost The last mile problem For tonight (/ Thursday) • Reading • Requirements Doc Sample • Power: • SMAD 11.4 • TLOM 14 • Mechanisms: • SMAD 11.6 (11.6.8 too) • TLOM ? • Fill in re ACS: TLOM: • Chapt. 6 (magnets) • Chapt. 11 (ACS) • Thinking • What can you build? • What can you test? Enginering 176 #6

  9. Preparation: Radios & Comms SMAD Chapter 13 TLOM Chapters 7,8,9 Technical requirements:Create a list of technical requirements - even if it has “TBD”s in it. (+ revisit mission rqts) For next Thursday, (March 7) • Systems design:create a good looking “cartoon” set of the spacecraft, orbit and ground segments • Tools selection: • Finite element • Design and layout • Presentation Graphics • Pick Something Physical Enginering 176 #6

  10. Supply: Sun: 1.34 kW/m2 Solar panels: h =~ 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 Power: Supply & Demand Enginering 176 #6

  11. Design Driver: Power • Increased Demands for Power: • Higher bandwidth (10 x BW = 10 x P) • Wide coverage area (5 x area = 5 x P) • Small GS antenna (1/10th diameter = 100 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: (a few % savings in power) • New array deployment (potential 2x to 100x) Enginering 176 #6

  12. Big Mil Spec Batteries Large Deployable, articulated solar arrays Large Volume ÷ Area: => Heat matters => heaters / heat pipes / radiators Small Commercial NiCads (but relatively larger fraction of total mass) Fixed, Body mounted cells (small V÷A => volume, not W, limit) => passive thermal Small v. Big approaches to Power Enginering 176 #6

  13. 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 h photovoltaics High cost, tight attitude control Other upgrades Power regulation & distribution, charging, demand side devices Power Affects all Engineering Aspects Enginering 176 #6

  14. 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 µp working 2x as hard is more efficient - Limit downlink: compression, GS antenna gain, optimal modulation, coding, use L or S band, spacecraft antenna gain / switch, selectable downlink data rate, Rx cycling, Tx off and scheduled ops. - Local DC / DC conversion where / when needed - Careful parts selection, dynamic clocks Enginering 176 #6

  15. Rechargeable Battery Options Enginering 176 #6

  16. Battery Charging Enginering 176 #6

  17. 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 area by: π(cylinder), 4 (sphere) or6 (cube) Do you care? Probably not. π2r 2r A vs. 6A πr2 vs. 4πr2 Enginering 176 #6

  18. Design for Solar PowerExample: Equatorial Earth Oriented Enginering 176 #6

  19. Power Budget and Power System Design Enginering 176 #6

  20. Potential Paradigm Breakers • Advanced deployables • Inflatables • Flexible photovoltaics • Power beaming • Cooperative swarms • Steerable Phased Arrays • Compression L’Garde Inflatable Enginering 176 #6

  21. Astrid Spacecraft Mass total: 27 kg Mass platform: 22.6 kg HxWxD: 290 x 450 x 450 Max Power 21.7 W Battery: 22 Gates Ni-Cd µprocessor: 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 Astrid(Swedish Space Corp) Enginering 176 #6

  22. Deployables: Why they might not • 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 (it’s physical) Galileo: didn’t x 1 • Flaws, cracks, delamination, vibration loosen/tighten • Minute population & test experience (the Buick antenna) • Total autonomy • High current actuation • Statistics - ways to work v. not Freja: did x 8 Enginering 176 #6

  23. 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 Common Deployables Marmon Ring Enginering 176 #6

  24. 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 Common Actuators Enginering 176 #6

  25. Buick’s deployable antenna goes to space(the board game you can play at home) Enginering 176 #6

  26. 1) Will it really be the same part? If you change materials, lubricants, loading, mechanical support, housing, coating, wiring, microswitches... It isn’t 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… 1) 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 $50kinspections and rebuilds Total - assuming nothing goes wrong $325k(not always a good assumption) Two Simple Questionsbefore designing that terrestrial component into your next spacecraft Enginering 176 #6

  27. Death, Taxes and... Enginering 176 #6

  28. What Deployables Really Cost Example: 4 deployable solar panels (cost ∆ compared with 1 large non-deployable panel) • Fab of 4 discrete paddles + 1 spare: $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 a hurry Enginering 176 #6

  29. Getting Beyond Deployables • Eliminate the need for deployables: • Larger launch envelope may be cheaper (and it’s 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. don’t 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 can’t eliminate might not work (graceful degradation) • Purchase insurance • Deployables must be testable at 1-g, 1 atm, room temp... Enginering 176 #6

  30. 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 µelectronics: 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

  31. Deployables Spec • Performance Applied torque or force, speed, accuracy, preload, angular momentum (eg mirror) • Weight / Power Allocations from system design spec • Envelope Mechanical & electrical interface, dimensions& interfaces bolt patterns, interface regions... • Environments Number of cycles, duration exposure to environments -> parts, materials, lubes… • Lifetime (op/non) # operating cycles, duration exposure • Structure Strength, fatigue life, stiffness • Reliability Allocation from system rel. spec - may drive specific approach & redundancy Enginering 176 #6

  32. Freja • Magnetospheric research • Launched October, 1992 • 214 kg, 2.2 m diameter • Development cost: $23M 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 • High “Q” passive thermal design; • Everything worked! (and still is working). Freja(Swedish Space Corp) Enginering 176 #6

  33. Galileo • Launched Oct. ‘89 • Mass: 2.5 Mg NASA JPL • GalileoHGA 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

  34. Enginering 176 #6

  35. 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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