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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

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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

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

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Enginering 176 #6


Box score 6 6

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

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Box score 6 6

(Some) STP-Sat Requirements

2.0System Definition2.1 Mission Description2.2 Interface Design2.2.1SV-LV Interface2.2.2SC-Experiments Interface2.2.3Satellite Operations Center (SOC) Interface3.0Requirements3.1 Performance and Mission Requirements3.2 Design and Construction3.2.1Structure and Mechanisms3.2.2Mass Properties3.2.3Reliability3.2.4Environmental Conditions3.2.4.1 Design Load Factors3.2.4.2 SV Frequency Requirements3.2.5Electromagnetic Compatibility3.2.6Contamination Control3.2.7Telemetry, Tracking, and Commanding (TT&C) Subsystem3.2.7.1 Frequency Allocation3.2.7.2 Commanding3.2.7.3 Tracking and Ephemeris3.2.7.4 Telemetry3.2.7.5 Contact Availability3.2.7.6 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

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Box score 6 6

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%

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Orbital insertion

1

2

3

4

5

6

Orbital Insertion

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Optics lesson 1 pinhole camera

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

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For tonight thursday

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?

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For next thursday march 7

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

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Power supply demand

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

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Design driver power

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)

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Small v big approaches to power

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

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Power affects all engineering aspects

Array & Battery SizeVolume, Mass, Cost ($10k/W), Risk

DeployablesCost & Risk, CG, Attitude control & perturbations, managing complexity

ThermalLarger dissipation => large fluctuations => heat pipes, louvers, structure upgrade

High h photovoltaicsHigh cost, tight attitude control

Other upgradesPower regulation & distribution, charging, demand side devices

Power Affects all Engineering Aspects

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Power cost impacts

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. Siliconhigher 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

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Rechargeable battery options

Rechargeable Battery Options

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Battery charging

Battery Charging

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Water cooler napkin back group picnic topics

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

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Design for solar power example equatorial earth oriented

Design for Solar PowerExample: Equatorial Earth Oriented

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Power budget and power system design

Power Budget and Power System Design

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Potential paradigm breakers

Potential Paradigm Breakers

  • Advanced deployables

    • Inflatables

    • Flexible photovoltaics

  • Power beaming

  • Cooperative swarms

  • Steerable Phased Arrays

  • Compression

L’Garde Inflatable

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Astrid spacecraft

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)

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Deployables why they might not

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

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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

Common Deployables

Marmon Ring

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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

Common Actuators

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Buick s deployable antenna goes to space the board game you can play at home

Buick’s deployable antenna goes to space(the board game you can play at home)

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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 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

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Death taxes and

Death, Taxes and...

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What deployables really cost

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

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Getting beyond deployables

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...

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Deployables checklist

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...

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Deployables spec

Deployables Spec

  • PerformanceApplied torque or force, speed, accuracy, preload, angular momentum (eg mirror)

  • Weight / PowerAllocations from system design spec

  • EnvelopeMechanical & electrical interface, dimensions& interfaces bolt patterns, interface regions...

  • EnvironmentsNumber of cycles, duration exposure to environments -> parts, materials, lubes…

  • Lifetime (op/non)# operating cycles, duration exposure

  • StructureStrength, fatigue life, stiffness

  • ReliabilityAllocation from system rel. spec - may drivespecific approach & redundancy

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Freja

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)

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Galileo

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?

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Box score 6 6

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Terrestrial stuff that works in space

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...

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