chameleon suitoct01
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A Chameleon Suit to Liberate Human Exploration of Space
Environments
Ed HodgsonHSSSI
October 30, 2001
2
Concept Summary
• Enabling Waste Heat Rejection From Full Suit Surface Area
• Controlled Suit Heat Transfer– Matches metabolic load and
environment– Layer contact and distance
(conduction changes)– Layer emissivity
• Eliminate Expendables• Simpler, Lighter Life Support
Sun HeatedSurfaces Insulated
Metabolic Heat Rejected ThroughTransmissive Surfaces With Low
Sink Temperature
MaximumInsulation Value
MaximumTransmissivity
MinimumEmissivity
MaximumLoft
Q Q
IntimateContact
MaximumEmissivity
4
Performance - Feasibility Assessment
Maximum Radiated Heat LoadFrom PLSS Area
0
100
200
300
400
500
600
700
800
40 80 120 160 200 240 280 320
Outer Surface Temperature of Suit (K)
Heat
Rej
ectio
n (W
atts
)
50 K150 K250 K
Sink Temp.
Maximum Sustained Work Rate
Minimum Resting Metabolic Rate
Skin Comfort Conditions
Average EVA Work Rate
Maximum Radiated Heat LoadFrom Whole Suit Area
0
100
200
300
400
500
600
700
800
40 80 120 160 200 240 280 320
Outer Surface Temperature of Suit (K)
Heat
Rej
ectio
n (W
atts
)50 K150 K250 K
Sink Temp.
Maximum Sustained Work Rate
Minimum Resting Metabolic Rate
Skin Comfort Conditions
Average EVA Work Rate
5
Performance - Mission Environments & Interactions
Heat Rejection Vs Sun Angle to Surface Normal
0
50
100
150
200
250
300
0 20 40 60 80 100
Sun Angle to Surface (degrees)
Heat
Rej
ectio
n (W
atts
/Sq.
M)
225 F
255 F
285 F
Sink Temp.
Heat Rejection Capability With and Without Directional Shading
0
100
200
300
400
500
600
700
800
900
0 15 30 45 60 75 90
Solar Elevation Angle (degrees)
Max
imum
Sus
tain
able
Met
abol
ic R
ate
(Wat
ts) No Directional Shading
Directional Shading
Average EVAMetabolic Rate
6
Performance - System Elements Requirements Derivation
Skin Surface...DeepSpace
Outer Suit Inner Suit
Conducting Layers with De-Activated Spacers
Suit Material Layers
SkinSurface...
Martian Night
Outer Suit Inner Suit
Insulating Suit Layerswith Activated Spacers
Suit Material Layers
Hot and Warm Environments • Max Metabolic Rate → 600 W• Emissivity → 0.85• Conductivity → 300 W/m2-°C• 6-layer Conductivity→ 50 W/m2-°C
Cold Environment (Mars Night)• Min Metabolic Rate → 100 W• Outer Layer Emissivity → 0.85• Conductivity → 0.96 W/m2-°C• 6-layer Conductivity→ 0.16 W/m2-°C
Radiation transport can be limited to acceptable loss for resting conditions in cold environment
Thermal resistance can be minimized to increase radiation transport for hot environment
7
Concept Evolution, Refinement and Growth Potential
• Conductive Velvet Interlayer Contact– Reduced temperature drop to
outer surface
• MEMS Directional Shading Louvers– Radiative heat rejection in
“impossible” environments
• Supplemental Heat Transport• Micro-Heat Pump Technology Rotating Reflective
Louvers
Incident IR From HotSurfaces - Totally Reflected
Higher Angle IR -Partially Reflected
Emitted IR From SuitSurface
Corner Reflectors -Retroreflective Surface
Plane ReflectiveSurface
8
EAP Layer Spacing Control Actuators
Thermally ConductiveFiber Felt
Insulating PolymerIsolation LayerPolymer Infra-redElectrochromic(2 active layers + SP electrolyte)
Positive Voltage Supply(conductive polymer?)Negative Voltage Supply(conductive polymer?)
IR Transparent Conductive Control Electrode(& temperature sensor)
Chameleon Suit Layer Structure
9
System Sensing & Control Basics
ComputerControl
text
PowerSupply
UserMetabolic
Rate
Local Temperature &Heat Flow
Layer SpacingControl
EmissivityControl
Active ProtectiveGarment
• Local Temperature & Centralized Metabolic Rate
• Local Temperature is Key– Outside surface sets feasibility
of heat rejection– Inside surface controls
comfort– Layer delta T gives heat flux
• Metabolic Rate– Sets comfort temperature– Sets total heat flux
10
System Sensing & Control• System Control Needs
– Maintain Thermal Comfort– Avoid Hot & Cold Touch
Temperatures
• Environmental Factors– Hot & Cold Extremes– Rapid Variation– Directional Sources
• Sun, Hot Surfaces
• Crew Motion– Contact Pressure
• Suit Control Zones
Effect of Sensing & Control Zone Angular Size
0
10
20
30
40
50
60
0 50 100 150 200Zone Angular Width (Degrees)
Tem
pera
ture
Err
or (C
)0
0.2
0.4
0.6
0.8
1
1.2
Rel
ativ
e H
eat R
ejec
tion
Temp Error, Tsink=-18Temp Error, Tsink=10Q relative, Tsink=-18Q relative, Tsink=10
TmaxT1
Control & Sensing Zones Inactive Zones
Head 11 GlovesTorso 32 ElbowsUpper Arm 24 KneesLower Arm 24 BootsUpper Leg 24Lower Leg 24Shoulders 7
Total 146
11
Sensing & Control Integration Options
• Driving Factors– Robust Control
• Simple signal and power interfaces
• Minimize harnesses • Redundancy
– Minimize Heat Leak– Minimize Power/Weight/Volume
of Control Electronics
• Control Basis– Total Heat Rejection– Skin Comfort temperature– Comfort Indicators
• Architecture Options– Centralized– Distributed
• Signal Transfer– Analog/Sensor inputs– Data Bus, Wireless– Effector Drivers– Power Distribution
12
Control And Feedback
• ~150 Zones, 5 layers => High I/O Count
• Centralized Control Requires Complex Data Transfer, High Data Rates
• Optimal Approaches in Dealing With High I/O Counts Are Based on a Distributed Processing Concept
• Distributed Control Zones for Segments of the Suit Simplify the I/O Requirements
ZONES
13
• Central Processor– Determines metabolic rate– Transmits inner wall T targets– Receives zone status & wall T
• Networked dedicated zone controllers– Receive T targets & local T’s– Locally send actuator control signals– Transmit inner wall T & status
• Signal transmission– Wireless IEEE 802.11B protocol– Alternate - signals on power lines
Zone Controllers
Control And FeedbackPreferred Implementation
14
Power Distribution• Current Technology Harnesses
– Weight, Reliability, Mobility Impacts
• “Smart” Garment Technology– Integrated Power and Signal
Distribution• Conductors woven in cloth
layers• Conducting polymer layers
– Integrated Sensing, Data Terminal, Actuator Control Elements on Chip
• Wireless Data Transmission, Local Control Components
– Only Power Physically Connects Layers (Thermal Short)
– Minimum Number of Connections
Fabric Effector Control
and Input Power Layers
Effectors
Embedded
Control
Power
Sensor
Wireless
Comm
15
Technology Base Assessment -Development Needs Key Areas
• Variable Geometry Insulation– Light weight, flexible biomimetic polymer actuators.– Durable and effective felt thermal contact material.
• Controlled Thermal Radiation– Effective thermal IR electrochromic polymers with high
contrast ratios– “Soft” MEMS directional louver implementations.
• “Smart” Garment Sensing and Control Integration• Cost Effective Integrated Garment Manufacturing
16
Variable Geometry Insulation Actuators
• Elongating polymers (MIT)– Conductive polymers (PPy, PAN)– liquid, gel or solid electrolytes– 2% linear , 6% volumetric at ~ 1V
• Bending polymers (UNM)– Ionic polymer-metal composites (Nafion-Pt)– need to prevent water leakage (encapsulation, better Pt
dispersion)– complete loop with <3V
17
Interlayer Thermal Contact
• Low Thermal Resistance Is Required – High Metabolic Rates– Warm Environments– Vacuum Conditions– Low Contact Pressure
• Carbon Fiber Felts Show Good Performance
• Durability in Application Requires Development
Carbon Felt Contact Conductance Vs. Compression
0100200300400500600700800
0 0.2 0.4 0.6 0.8 1
Compression (mm)
Con
duct
ance
(W/S
q.M
)
18
Electro-emissive Technologies
• Most Broadband Infra-red Research Has Been With Inorganic EC Materials (WO3)
• Contrast Ratios > 2:1 in the Thermal IR Shown
• Polymer EC Materials are Under Study by Numerous Investigators
• Much Further Development is Needed
19
Directional Shading Louvers• MEMS Louver Technology is Under Development
for Satellite Applications– Shown to Provide Effective Emissivity Modulation– Options Under Study Include Pivoting Louvers Required
for Chameleon Suit Directional Shading
• Louver Size for IR Corner Reflectors is Compatible With Application (~.03 mm deep)
• Major Development Challenges– Integration in Flexible Garment– Removable Louver Layers
20
Sensing & Control Integration
• Systems Embodying the Required Functions Are Being Developed for Many Uses
• Key Challenges Will Be:– Space Environment Compatibility– Limiting Weight & Maintaining Flexibility With Many Layers
21
Mission Benefits Assessment• Substantial Launch Mass
Savings– Savings For All Missions– EVA Intensive 1000 Day
Class Missions Benefit Most
• ~ 3.5 Kg Reduction in EVA Carry Mass
• Capability for Non-Venting Operations in Most Environments– Science & Servicing
Flexibility
Chameleon Suit Launch Mass Savings
1
10
100
1000
10000
1 10 100 1000Number of 2 Person EVA's / Mission
Laun
ch M
ass
Savi
ngs
(Kg)
3820
Units Launched
NASA Mars Design Reference Mission
Lagrange Point Assembly & LunarVisit Missions
ISS Operations
22
Summary & Conclusions
• Studying the Chameleon Suit Reveals Many New Challenges– None Have Yet Proved Insoluble
• Many Required Technology Advances are Pursued Elsewhere– Specific Development and
Adaptation Work is Required
• Potential Benefits to NASA are Substantial and Real– Further Study Should be Pursued
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