《空中交通运输系统》（英文版）chapter 4 mcmanuslactur2

SSPARC Using architecture Models to Understand Policy Impacts ncreas cost B-TOS Policy increases Swarm of small sats.3 launch probability doing observation Utility for mu of success Probability of Success From Weigel, 2002 SSPARC Using architecture Models to Consider uncertaint Tech Sat Constellation of satellites doing observation of moving objects on the grou Uncertainties driven by instrument performance/cost

15 Space Systems, Policy, and Architecture Research Consortium ©2002 Massachusetts Institute of Technology 29 Using Architecture Models to Understand Policy Impacts B-TOS Case Study: Probability of Success Impact of 1994 U.S. Space Transportation Policy for a Minimum Cost Decision Maker 0.98 0.985 0.99 0.995 1 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% B-TOS Architecture Probability of Launch Success (Lifecycle total) Probability of Success Utility Cost of US Launch Policy: B-TOS Case Study Using Min Cost Rule 0.98 0.985 0.99 0.995 1 0 100 200 300 400 500 600 700 800 Lifecycle Cost ($M) A B C D Utility Cost 100% of B-TOS architectures have cost increase under restrictive launch policy for a minimum cost decision maker 98% of B-TOS architectures have increased launch probability of success under restrictive launch policy for a minimum cost decision maker Restrictive launch policy Unrestrictive launch policy Policy increases cost Policy increases launch probability of success B-TOS • Swarm of small sats. doing observation • Utility for multiple missions From Weigel, 2002 Space Systems, Policy, and Architecture Research Consortium ©2002 Massachusetts Institute of Technology 30 Using Architecture Models to Consider Uncertainty Performance and Cost move differently for different architectures under uncertainty TechSat • Constellation of satellites doing observation of moving objects on the ground • Uncertainties driven by instrument performance/cost From Walton, 2002 [Martin, 2000]

一 SSPARC Changes in User Preferences Can be Quickly Understood Architecture trade space reevaluated in less tha one hour User changed preference nting X-TOS SSPARC Assessing Robustness and Adaptability Pareto front shows trade-off of accuracy and cost Determined by number of satellites in swarm Could add satellites to increase capability ,吕海总 Most desirable architecture Cost

16 Space Systems, Policy, and Architecture Research Consortium ©2002 Massachusetts Institute of Technology 31 Changes in User Preferences Can be Quickly Understood 40 42 44 46 48 50 52 54 56 58 60 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Lifecycle Cost ($M) U t i l i t y 40 42 44 46 48 50 52 54 56 58 60 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Lifecycle Cost ($M) U t i l i t y Original Revised User changed preference weighting for lifespan Architecture trade space reevaluated in less than one hour X-TOS Space Systems, Policy, and Architecture Research Consortium ©2002 Massachusetts Institute of Technology 32 Assessing Robustness and Adaptability • Pareto front shows trade-off of accuracy and cost • Determined by number of satellites in swarm • Could add satellites to increase capability 0.98 0.985 0.99 0.995 1 100 1000 Lifecycle Cost ($M) Utility A D E C B Utility Cost Most desirable architectures B-TOS

SSPARC Questioning User Desires Best low-cost mission do only one job well More expensive, higher performance missions require more vehicles Higher-cost systems can do multiple missions Is the multiple mission idea a good one? Color scale: Life Cycle Cost, 1380 data points, grid: 75x75, density: 0. 08 A-TOS Swarm of very mple satellites taking ionospheric measurements creasing Several different Equatorial Utility SSPARC Understanding Limiting Physical or Mission constraints 4000.00 SPACETUG General purpose ort 3000.00 transfer 500.00 Different 200000 propulsion systems and 100000 Lines sho increasing fuel mass fraction Utllty (dimensionless) Hits a"wall"ofeither physics(can't change !) or utility(can)

©2002 Massachusetts Institute of Technology 33 Low Biprop Medium Biprop High Biprop Extreme Biprop Low Cryo Medium Cryo High Cryo Extreme Cryo Low Electric Medium Electric High Electric Extreme Electric Low Nuclear Medium Nuclear High Nuclear Extreme Nuclear 17 Space Systems, Policy, and Architecture Research Consortium • • • • Equatorial Utility High Latitude Utility A-TOS • Swarm of very simple satellites measurements • Several different missions Questioning User Desires Best low-cost mission do only one job well More expensive, higher performance missions require more vehicles Higher-cost systems can do multiple missions Is the multiple mission idea a good one? taking ionospheric Space Systems, Policy, and Architecture Research Consortium 34 0.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00 3500.00 4000.00 0.00 0.20 0.40 0.60 0.80 1.00 Utility (dimensionless) Cost (M$) SPACETUG • General purpose orbit transfer vehicles • Different propulsion systems and grappling/obser vation capabilities • Lines show increasing fuel mass fraction ©2002 Massachusetts Institute of Technology Understanding Limiting Physical or Mission constraints Hits a “wall” of either physics (can’t change!) or utility (can)

SSPARC Integrated Concurrent Engineering (ICE ICE techniques from Caltech and JPL Linked analytical tools with human experts in the loop Very rapid design iterations Result is conceptual design at more detailed level than seen in architecture studies Allows understanding and exploration of design alternative a reality check on the architecture studies-can the vehicles called for be built. on budget with available technologies? SSPARC ICE Process(CON with MATE) Directed design Sessions allow very fast production of preliminary designs raditionally, design MATE allows utility be assessed real time synchronizes actio

Space Systems, Policy, and Architecture Research Consortium 35 • • • • • alternatives • ©2002 Massachusetts Institute of Technology Integrated Concurrent Engineering (ICE) ICE techniques from Caltech and JPL Linked analytical tools with human experts in the loop Very rapid design iterations Result is conceptual design at more detailed level than seen in architecture studies Allows understanding and exploration of design A reality check on the architecture studies - can the vehicles called for be built, on budget, with available technologies? Space Systems, Policy, and Architecture Research Consortium 36 Thermal Structures Communication Command and Data Handling Configuration Power Propulsion Attitude Determination and Control Mission Systems ICE-Maker Server Cost Reliability MATE ICE Process Leader computer tool AND human expert Verbal or online chat between chairs synchronizes actions Electronic communication between tools and server Key system attributes passed to MATE chair, helps to drive design session • Directed Design Sessions allow very fast production of preliminary designs • Traditionally, design to requirements • Integration with MATE allows utility of designs to be assessed real time ©2002 Massachusetts Institute of Technology ICE Process (CON with MATE) “Chairs” consist of 18

一 SSPARC ICE Result- XTOS Vehicle Early Designs had excessively large fuel tanks and bizarre Showed limits of coarse modeling done in architecture studies Vehicle optimized for best utility-ma life at the lowes practical altitude SSPARC SPACETUG Biprop One-Way GEO Tu 13 12 kg dry mass, 11689 kg wet mass Quite big(and therefore expensive); not very practical (?) Scale for all images: black ylinder is / meter ng by I meter in

Space Systems, Policy, and Architecture Research Consortium 37 • Early Designs had excessively large fuel tanks and bizarre shapes • Showed limits of in architecture studies • Vehicle optimized for best utility - maximum life at the lowest practical altitude ©2002 Massachusetts Institute of Technology ICE Result - XTOS Vehicle coarse modeling done Space Systems, Policy, and Architecture Research Consortium 38 • • Scale for all images: black cylinder is 1 meter long by 1 meter in diameter ©2002 Massachusetts Institute of Technology SPACETUG Biprop One-Way GEO Tug 1312 kg dry mass, 11689 kg wet mass Quite big (and therefore expensive); not very practical (?); 19

一 SSPARC SPACETUG Tug Family designed in a day) CryogenIc Wet Mass: 1 1689 k Wet Mass: 6238 kg Electric-One way Electric-Return Trip Wet Mass: 997 kg et Mass: 1112 kg SSPARC Learning from the IcE results: Mass Distribution Comparison Electric Cruiser Biprop one-way Low ISP fuel requires very large mass fraction to do mission Other mass fractions reasonable, with manipulator system power system, and structures and mechanisms dominating

Space Systems, Policy, and Architecture Research Consortium 39 Bipropellant Cryogenic ©2002 Massachusetts Institute of Technology SPACETUG Tug Family (designed in a day) Electric – One way Electric – Return Trip Wet Mass: 11689 kg Wet Mass: 6238 kg Wet Mass: 997 kg Wet Mass: 1112 kg Space Systems, Policy, and Architecture Research Consortium 40 Power 11% Propulsion (dry) 2% Structures & Mechanisms 17% Thermal 5% Mating System 27% Payload 0% C&DH 0% Link 1% ADACS (dry) 0% Pressurant 0% Propellant 37% Propellant 88% Pressurant 0% Power 1% Link C&DH 0% 0% ADACS (dry) 0% Payload 0% Mating System 3% Propulsion (dry) 6% Structures & Mechanisms 2% Thermal 0% Electric Cruiser • Low ISP fuel requires very large mass fraction to do mission • power system, and structures and mechanisms dominating ©2002 Massachusetts Institute of Technology Learning from the ICE results: Mass Distribution Comparison Biprop one-way Other mass fractions reasonable, with manipulator system, 20

一 SSPARC More Than mass fractions LEO Tender 1 Power System Mass Breakdown mass summary Detailed information can be drawn from subsystem sheets. including efficiencies, degradations temperature tolerances, and areas at array area SSPARC Trade space Check Biprop ◆ Storable Biprop Nuclear △ B prop GEO tug o Electric GEO cruiser 口 Cryo GEO tug O SCADS 口 Electric GEO Tug Electric Utility The GEO mission is near the"wall""for conventional propulsion

Space Systems, Policy, and Architecture Research Consortium ©2002 Massachusetts Institute of Technology 41 More Than Mass Fractions 0%1% 16% 5% 3% 2% 21% 0% 52% 0% ADACS (dry) C&DH Link Power Propulsion (dry) Structures & Mechanisms Thermal Mating System Payload Propellant Pressurant Power System Mass Breakdown Solar array mass 66% Battery mass PMAD mass 19% 9% Cabling mass 6% Minimum efficiency 24.5 % Maximum efficiency 28.0 % Nominal temperature 28.0 C Temperature loss 0.5 %/deg C Performance degredation 2.6 % / year Minimum temperature 0.5 C Maximum temperature 85.0 C Energy density 25.0 W / kg Solar array mass 150.6685167 kg Total solar array area 9.965098159 m^2 # of solar arrays 2 # Individual solar array area 4.98254908 m^2 LEO Tender 1 mass summary Detailed information can be drawn from subsystem sheets, including efficiencies, degradations temperature tolerances, and areas Select solar array material: Triple Junction (InGaP/GaAs/Ge) 6 Space Systems, Policy, and Architecture Research Consortium ©2002 Massachusetts Institute of Technology 42 Trade Space Check The GEO mission is near the “wall” for conventional propulsion 21

SPACETUG SSPARC LEO Tender family LEO 1-1404 kg wet LEO 2-1242 kg wet Tenders Orbit transfer vehicles that live in a of orbits LEO 4-1782 kg wet E0 4A-4107 ke wet Do low Delta-V transfers service observation SSPARC Tenders on the tradespace STorable Biprop o Electric GEo cruiser General Tender 口 Cryo GEO tug O SCADS Mission-specific 口 Electric GEO Tug Tend ■LEo1 tender ▲LEo2 tender Electric Tender? o LEo 4 tender 口LEo4 A tender The Tender missions are feasible with conventional propulsion

Space Systems, Policy, and Architecture Research Consortium 43 SPACETUG Tenders • Orbit transfer vehicles that live in a restricted, highly populated set of orbits • Do low Delta-V transfers, service, observation ©2002 Massachusetts Institute of Technology LEO Tender Family LEO 1 - 1404 kg wet LEO 2 - 1242 kg wet LEO 4 - 1782 kg wet LEO 4A - 4107 kg wet Space Systems, Policy, and Architecture Research Consortium 44 The Tender missions are feasible with conventional propulsion ©2002 Massachusetts Institute of Technology Tenders on the tradespace 22

SSPARC What you will learn Trade space evaluation allows efficient quantitative assessment of system architectures given user needs State-of-the-art conceptual design processes refine selected architectures to vehicle preliminary designs Goal is the right system, with major issues understood (and major problems ironed out)entering detailed esign Emerging capability to get from needs to robust solutions quickly, while considering full range of options, and maintaining engineering excellence

Space Systems, Policy, and Architecture Research Consortium 45 • • • design Emerging capability to get from user needs to robust solutions quickly, while considering full range of options, and maintaining engineering excellence ©2002 Massachusetts Institute of Technology What you will learn Trade space evaluation allows efficient quantitative assessment of system architectures given user needs State-of-the-art conceptual design processes refine selected architectures to vehicle preliminary designs Goal is the right system, with major issues understood (and major problems ironed out) entering detailed 23