#1 documentation & missions
TRANSCRIPT
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Your Guide: Dr. Rick Fleeter
Tour Duration: < 2 weeks
Starting Point: All tools, nothing to build
Destination: You design it
In Your Backpack: Elements: G&C, Structures, Orbits (?)
Class Presentations and Notes
Expeditionary Party: The Class, Your Texts, The Internet
Your Group
Teaching Assistant(?) and me
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Water / Bouyancy / Fluid Mechanics
+ Breathing, Conditioning, Stroke Mechanics
=> lets go for a swim
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Four Classes (1 and 2)
1. What is design, What is the Design Process
What are you going to design (mission statement)Some examples of missions and mission statements
Requirements and the design process
homework: form groups, pick mission, describe
2. Learning from other missionsGuess their mission statement and requirements
Other ways to accomplish same mission(in space or on ground)
workshop and homework: sketch your designspacecraft / payload / orbit / launch / ground
top level requirements outline
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Four Classes
3. 5 Minute presentation of your design:1 from ea. group
What technologies are mission critical?What are tech obstacles in space today?
4. (All members minus 1): present design specifics Mission and Specific Requirements How to do mission with current tech
What would change with tech innovation
Transportation: influence on mission, design, costInnovating around launch issues
Documentation for student projects
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Your missions for Next Class:
Organize into groups / squadre- minimum 3 people
- maximum 5 people
- seek diversityInvent / select ~ 2 missions
describe in
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What its all about
Ultimately: Design a Space Capability Mission Statement
Spacecraft / Payload
Launch / Orbit
Operations / User Interface
Financing
Identify and prove Technology Requirements
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You AreHere
Design Roadmap
Define
MissionConcept
Solutions &
Tradeoffs
Conceptual
DesignRequirements Analysis
OrbitPropulsion/ V
CommsAttitude
Determine
& Control
Launch GroundStation
Thermal /StructureDeployables
InfoProcessing
Top Level Design
Iterate Subsystems
Suppliers / Budgets
Parts
SpecsMass
Power
$
V
Link BitsMaterials
Fab
Detailed DesignFinal Performance
Specs & Cost
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Mission Definition: Black tie & prime rib for 300 at the Plaza
vs.
Beer and hot dogs in the park
Preliminary Design: Select entr, drinks, desert, type of music
=> 1st credible cost estimate possible
Detailed Design:
# bottles of Schlitz / Perrier & Jouet, m2 of cake, place markers,kg of beef, invitations: color, paper...=> may commit to fixed price
ICD (Interface Control Document): Cash bar? Who supplies the flowers? (Flowers? What flowers?).
Chairs? Valet Parking...
Management and Standards Waiters in tuxedos, sommelier and served hors douvres vs. bufet
Build vs. Buy
Can you bake those cookies for less than7/kg? (and so what!) What wont get done while youre busy at home baking?
If life is a banquet...
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Power: Supply & Demand Supply:
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
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Small v. Big approaches to Power
Big Mil Spec Batteries
Large Deployable, articulated solararrays
Large Volume / Area: => Heat
matters=> heaters / heat pipes /radiators
Small
Commercial NiCads
(but relatively larger fraction of totalmass)
Fixed, Body mounted cells (small VA =>volume, not W, limit) => passive thermal
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POWER EFFECTS EVERYTHING
Array & Battery SizeVolume, Mass, Cost ($10k/W), Risk
Deployables Cost & Risk, CG, Attitude control & perturbations, managingcomplexity
Thermal Larger dissipation => large fluctuations=> heat pipes, louvers, structure upgrade
High photovoltaicsHigh cost, tight attitude control Other upgrades Power regulation & distribution,
charging, demand side devices
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Power: Cost Impacts Solar Panel Area Cost of Deployables
Pointing requirements Cost / mass of batteriesTracking array Structural support / mount batteriesThermal 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,
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
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Mission Cost / Complexity DriversTechnical - slide #1
Feature
Impact
Electric Power Array size High efficiency photovoltaics(more of it and Deployables Batteriesat higher duty cycle) Thermal Effects RFI and stray fields Tracking arrays
Thermal Design / Analysis complexity How to test?(special thermal Reduces overall thermal mass Heaters, coolers => more powerrequirements for Power supply reliability Transients (deployment, slews,discrete components) Restricts attitude options lock loss...)
Data Rate Large memory Data analysis cost(fast downlink) Wider frequency allocation Large Ground Station antenna Processor: push speed More complex GS receiver
Software efficiency Directional on-board antenna(s)
Processing Power Electric power, volume, mass Mature development environment?(using latest, greatest lack of "space" features (e.g. EDAC Integrated support circuits?available processors) multiple copies, current monitor...) Available development boards? "Efficient" code (i.e. complex H'wr, s'wr, documentation bugs expensive, non-readable, test?)
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Mission Cost / Complexity DriversTechnical - slide #2
Feature Impact Raw Mass Bigger test fixtures No piggyback / shared launch slots("250 kg of silicon Difficult to transport ACS actuator scale updoesn't add to Launch cost increase -> tougher standards system widecomplexity") (rules, reviews, signoffs, meetings, unwinnable arguments...) Difficult safety qual. 50 kg to Pluto: not a small spacecraft!
Attitude Control & Sensor upgrades: no home brews Actuator upgrades: quieter wheelsDetermination Different sensor suite Different actuator suite(0.25 v. 0.05) (e.g. HCI no better than 0.1) (e.g. mag coils = insufficient authority) Need higher loop bandwidth: rate sensors (gyros) Structure rigidity: heavier and more complex modeling Thermal effects significant: more complex thermal mgt & modeling Alignment precision: complex machining, testing, calibration (plus maintaining alignment in transport, test, launch environments) ACS Algorithmic complexity - more perturbations count - how to test?
V Complexity: control, integration, launch prep Safety: pressure, chemicals, pyros... Mass distribution restriction Additional ACS modes Higher launch mass (see above) Orbit determination Cost of propulsion system itself
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Mission Cost / Complexity DriversTechnical - slide #3
Feature Impact
Reliability / Redundancy: 2+x mass / volume Limited selection of hardwareLifetime Hi Rel parts: older, longer lead, more $, lower performance
(usually results in higher parts count and lower reliability)Mil-Spec batteries: 100x cost, only large sizes, redundancy difficultAnalysis cost: FMECA - how to prove reliability - extensive testing
"Special" Clean spec: overhead of clean facilities, access hassleSpecial orbit: custom launch and/or on-board propulsionHighly integrated design (payload / bus / launch vehicle):
religious wars, pre-integration test fixturing, finger pointing @ integration,
full team cooperation throughout mission ops phase Low mass: modeling, high cost materials, testing low magnetic environment: booms, testing, materials and wiring, rework, retestLow Outgas: materials restrictions, bake-out-> In general, specials move the team off optimal
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Mission Cost / Complexity DriversManagement - slide #1
Feature Conventional Small / Low Cost QC / Traceability Separate QC Team Responsibility of each engineer
Documentation Documentation team: imposes Minimal documentation - overhead on engineers restricted to docs needed and read by engineers
Heritage De Facto Mandatory Used only when cheaper / faster Reviews Infrequent, huge, critical, frequent, small, focused, brief, week(s) long non- critical
Contract CPFF Fixed Price - delivery on orbit
Risk not tolerated (infinite failure cost) accepted (risk v. $ traded off) (officially)Standards externally imposed - infinite price created / negotiated by engineers price is negotiable
Staffing by slot Diverse team - all always busy
Staffing insurance by documentation per slot buddy system
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Mission Cost / Complexity DriversManagement - slide #2
Feature Conventional Small / Low Cost Tools minimum: large # hours @ low $/hr maximize: thus minimize total $, minimum organizational complexity
Operations dedicated staff @ dedicated facility minimal staff, GS on site "person in the loop" local ops or via internet
exploit spacecraft autonomy
Intra-team interface Documentation engineer - to - engineer
Staff Organization segregated by technical specialty integrated project
Hardware Flow specialty group to specialty group same team cradle to on-orbit ops
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Cost Driver Cost Saving Tactics Power Requirement Duty Cycle Sun Pointing offload secondary payloads Reduce margins
Tight Attitude Control Tight attitude determination instead
High Speed Downlink Duty cycle (truncate instrument data flux)
On-board compression (2:1 is easy, 10:1 possible) Do the best you can - it's better than you think: variable data
Choose orbit for better linkrate / tolerate link fallibility Tight Thermal Power down during hot seasonsRequirements Use instruments as heaters
General Budget Let mass grow Offload some of payload Don't conformal coatPanics Let volume grow - no deployables
Higher inclination orbit - local, not remote, GS No clean room - use "remove before flight" covers Startup related program - give people someplace to go Use flight-spare and leftover components Fly protoflight hardware - don't build flight hardware
Reducing Cost & Complexity
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How to succeed in microspace... ...without really trying
1. It doesnt have to be difficult to be good Your engineering education = your #1 asset and your #1 liability
2. Pick easy problems (or simplify hard ones)
Low power / Low data rate
Minimal stabilization / short life time
No propulsionSmall & Aluminum
3. Solve appropriately Match tools to job
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Documentation Basic Rule: Dont write what no one will read.
Easy documentation:
Email exchanges - Photographs of everything
Manufacturers data on purchased parts - Test & failure logs
Videos of procedures - Well documented code
Automatic documentation
Fabrication drawings & schematic diagrams - Block diagrams
Documents worth writing
ICDs - System Requirements Documents
(H&Swr) - Launch environment
Cabling diagram - Thermal / Structure analysisreports
Users manual - Test plans & results
Contracts, change orders etc.
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2.0 System Definition
2.1 Mission Description
2.2 Interface Design
2.2.1 SV-LV Interface 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
3.2.4 Environmental Conditions
3.2.4.1 Design Load Factors
3.2.4.2 SV Frequency Requirements
3.2.5 Electromagnetic Compatibility
3.2.6 Contamination Control
3.2.7 Telemetry, 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
(Some) STP-Sat Requirements
NB: this is
an excerpt
of the
Contents -
entire docs
are (or will
be) on the
class site
Requirements & Sys
Definition go together
Highly structured
outline form is
clearest and
industry standard
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Mission: Entertainment: Encounter
Mission Statement: Use a Solar Sail to propel 1 kg of DNA Samples
out of solar system.Escape trajectory must be verified
H
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Lunar Impactor / FLASH;
Impact lunar surface at > 10 km/s
Mission Statement:
Impact lunar surface with minimum 5 kg massImpact visible from earth during night
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STAR: Student Telescopefor Astronomical Research
Mission Statement: Place a useful optical telescope in LEO that
can be operated by students worldwide
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Echo Mission Statement:place a large retroreflector in LEO
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TAO (The Art Of) All operating specs and missions negotiable Buildable by students with no money in < 1 year
Insignificant launch mass (preferably < 5 kg)
Demonstrate nano launch vehicle application
Mission Statement: Build a satellite that does something and can be
built by
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Cubesat Kits
Teather:Power Generation/Propulsion
VLF PropagationParticle impactmicro Space Elevator
Micro Solar Sail:Leave LEO?Other apps:night illuminationadvertisingdrag for reentry
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Climate monitor / control
Advertising from orbitPlanetary defense (asteroid detection) Space agriculture (0-g grapes)
ASAT Defense (= ASAT?)Cube-sat, Can-sat (TAO)Space Elevator tech demo (e.g. tether)
Other Mission Ideas
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Your missions for Next Class:
Organize into groups / squadre
- minimum 3 people
- maximum 5 people
- seek diversityInvent / select ~ 2 missions
describe in