#1 documentation & missions

8/8/2019 #1 Documentation & Missions

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2/31

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


3/31

Water / Bouyancy / Fluid Mechanics

+ Breathing, Conditioning, Stroke Mechanics

=> lets go for a swim


4/31

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


5/31

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


6/31

Your missions for Next Class:

Organize into groups / squadre- minimum 3 people

- maximum 5 people

- seek diversityInvent / select ~ 2 missions

describe in


7/31

What its all about

Ultimately: Design a Space Capability Mission Statement

Spacecraft / Payload

Launch / Orbit

Operations / User Interface

Financing

Identify and prove Technology Requirements


8/31

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


9/31

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...


10/31

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


11/31

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


12/31

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


13/31

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?)


15/31


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


16/31


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


17/31

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


18/31

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


19/31

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


20/31

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


21/31

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


23/31


24/31

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


25/31

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


26/31

STAR: Student Telescopefor Astronomical Research

Mission Statement: Place a useful optical telescope in LEO that

can be operated by students worldwide


27/31

Echo Mission Statement:place a large retroreflector in LEO


28/31

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


29/31

Cubesat Kits

Teather:Power Generation/Propulsion

VLF PropagationParticle impactmicro Space Elevator

Micro Solar Sail:Leave LEO?Other apps:night illuminationadvertisingdrag for reentry


30/31

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


31/31

Your missions for Next Class:

Organize into groups / squadre

- minimum 3 people

- maximum 5 people

- seek diversityInvent / select ~ 2 missions

describe in