Box score: 6 6

1
Box score 6 / 6

• 6 - Power Mechanisms
• Photovoltaics Solar panels
• Maximizing the minimum
• Batteries and chargers
• Deployables
• Why moving parts dont
• 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

• 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

2
the word from our sponsor

• A large number of small monthly payouts ------

adds up to a lot of negative equity ------
and even more with foregone interest included
------
3
Design Roadmap
Or maybe Here
You Are Here
Define Mission
Concept
Solutions Tradeoffs
ConceptualDesign
Requirements
Analysis
Top Level Design
PartsSpecs
Suppliers / Budgets
MaterialsFab
Iterate Subsystems
Final Performance Specs Cost
Detailed Design
4
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 Relia
bility 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 (TTC) 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
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
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 gt R 12.5 Stage payload Mass Fraction 0.8
TwoSTO ? ?V 10000m/s Total Mass 3100 kg
Total PayMF 3.2
6
Orbital Insertion
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
gt 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
8
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)

• Requirements Doc
• Mission Requirements
• System Definition
• Begin Tech Requirements
• Launch Strategy
• Primary LV and cost
• The last mile problem

• 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 requirementsCreate a list of
  technical requirements - even if it has TBDs in
  it. ( revisit mission rqts)

• Systems designcreate a good looking cartoon
  set of the spacecraft, orbit and ground segments

• Tools selection
• Finite element
• Design and layout
• Presentation Graphics

• Pick Something Physical

10
Power Supply Demand

• Supply
• Sun 1.34 kW/m2
• Solar panels h 20 gt 250W/m2
• 50 of electricity is heat gt At ops. temps,
  Radiation300 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
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 25may 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)

12
Small v. Big approaches to Power

• Small
• Commercial NiCads (but relatively larger
  fraction of total mass)
• Fixed, Body mounted cells (small VA gt volume,
  not W, limit) gt passive thermal

• Big
• Mil Spec Batteries
• Large Deployable, articulated solar arrays
• Large Volume Area gt Heat matters gt heaters
  / heat pipes / radiators

13
Power Affects all Engineering Aspects

• Array Battery Size Volume, Mass, Cost (10k/W),
  Risk
• Deployables Cost Risk, CG, Attitude control
  perturbations, managing complexity
• Thermal Larger dissipation gt large
  fluctuations gt heat pipes, louvers,
  structure upgrade
• High h photovoltaics High 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
batteries  Tracking array  Structural support
/ mount batteries  Thermal issues GC
disturbance by array - internal dissipation
More power -gt more data -gt - large day / night
? - more processor cost Heavier spacecraft
- higher radio memory costs - more costly
launch  Higher launch cost -gt Consider GaAs
vs. Silicon higher rel. required -gt higher
parts count and cost A weapon Power
Conservation - Duty cycle 75 W Tx _at_ 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
15
Rechargeable Battery Options
16
Battery Charging
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 p(cylinder), 4
(sphere) or6 (cube) Do you care? Probably not.
p2r
2r
A vs. 6A
pr2 vs. 4pr2
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Design for Solar PowerExample Equatorial Earth
Oriented
19
Power Budget and Power System Design
20
Potential Paradigm Breakers

• Advanced deployables
• Inflatables
• Flexible photovoltaics
• Power beaming
• Cooperative swarms
• Steerable Phased Arrays
• Compression

LGarde Inflatable
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)
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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 (its physical)

Galileo didnt 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

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

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Buicks deployable antenna goes to space(the
board game you can play at home)
26
Two Simple Questionsbefore 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 isnt 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)

27
Death, Taxes and...
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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 GC 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
29
Getting Beyond Deployables

• Eliminate the need for deployables
• Larger launch envelope may be cheaper (and its
  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.
  dont 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 cant 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

• 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

• 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 -gt 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

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 (L1 to 15 meters)
deployed 1m and 2m fixed boom spacecraft
separation 4 pyro bolts plus standard marmon
ring Orbit insertion2 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)
33
Galileo
Launched Oct. 89 Mass 2.5 Mg NASA JPL

• Galileo HGA 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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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