A Chameleon Suit to Liberate Human Exploration of Space Environments. Ed Hodgson HSSSI October 30, 2001

Transcription

1 A Chameleon Suit to Liberate Human Exploration of Space Environments Ed Hodgson HSSSI October 30, 2001

2 Concept Summary Maximum Loft Q Maximum Insulation Value Sun Heated Surfaces Insulated Minimum Emissivity Intimate Contact Metabolic Heat Rejected Through Transmissive Surfaces With Low Sink Temperature Q Maximum Transmissivity Maximum Emissivity 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 2

3 Mission Needs Addressed 3

4 Performance - Feasibility Assessment 800 Maximum Radiated Heat Load From PLSS Area 800 Maximum Radiated Heat Load From Whole Suit Area Heat Rejection (Watts) Maximum Sustained Work Rate Sink Temp. 50 K 150 K 250 K Average EVA Work Rate Minimum Resting Metabolic Rate Skin Comfort Conditions Heat Rejection (Watts) Maximum Sustained Work Rate Sink Temp. 50 K 150 K 250 K Average EVA Work Rate Minimum Resting Metabolic Rate Skin Comfort Conditions Outer Surface Temperature of Suit (K) Outer Surface Temperature of Suit (K) 4

5 Performance - Mission Environments & Interactions Heat Rejection (W atts/sq.m) Heat Rejection Vs Sun Angle to Surface Normal Sink Temp F F F Sun Angle to Surface (degrees) 900 Heat Rejection Capability With and Without Directional Shading Maximum Sustainable Metabolic Rate (Watts) Average EVA Metabolic Rate No Directional Shading Directional Shading Solar Elevation Angle (degrees) 5

6 Martian Night Outer Suit Performance - System Elements Requirements Derivation Suit Material Layers... Insulating Suit Layers with Activated Spacers Inner Suit Skin Surface Cold Environment (Mars Night) Min Metabolic Rate 100 W Outer Layer Emissivity 0.85 Conductivity 0.96 W/m 2 - C 6-layer Conductivity 0.16 W/m 2 - C Radiation transport can be limited to acceptable loss for resting conditions in cold environment Suit Material Layers Hot and Warm Environments Deep Space Outer Suit... Conducting Layers with De-Activated Spacers Inner Suit Skin Surface Max Metabolic Rate 600 W Emissivity 0.85 Conductivity 300 W/m 2 - C 6-layer Conductivity 50 W/m 2 - C Thermal resistance can be minimized to increase radiation transport for hot environment 6

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 Plane Reflective Surface Corner Reflectors - Retroreflective Surface Emitted IR From Suit Surface Higher Angle IR - Partially Reflected Incident IR From Hot Surfaces - Totally Reflected Micro-Heat Pump Technology Rotating Reflective Louvers 7

8 Chameleon Suit Layer Structure EAP Layer Spacing Control Actuators Thermally Conductive Fiber Felt Insulating Polymer Isolation Layer Polymer Infra-red Electrochromic (2 active layers + SP electrolyte) Positive Voltage Supply (conductive polymer?) Negative Voltage Supply (conductive polymer?) IR Transparent Conductive Control Electrode (& temperature sensor) 8

9 System Sensing & Control Basics User Metabolic Rate Computer Control Layer Spacing Control Power Supply Local Temperature & Heat Flow Emissivity Control text Active Protective Garment 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 9

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 Temperature Error (C) Effect of Sensing & Control Zone Angular Size Temp Error, Tsink=-18 Temp Error, Tsink=10 Q relative, Tsink=-18 Q relative, Tsink=10 Tmax T Zone Angular Width (Degrees) Control & Sensing Zones Head 11 Gloves Torso 32 Elbows Upper Arm 24 Knees Lower Arm 24 Boots Upper Leg 24 Lower Leg 24 Shoulders 7 Total 146 Inactive Zones Relative Heat Rejection

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 11

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 12

13 Control And Feedback Preferred Implementation 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 B protocol Alternate - signals on power lines Zone Controllers 13

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 Sensor Embedded Control Wireless Comm Effectors Fabric Effector Control and Input Power Layers Power 14

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 15

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 16

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 Conductance (W/Sq.M) Carbon Felt Contact Conductance Vs. Compression Compression (mm) 17

18 Electro-emissive Technologies Most Broadband Infra-red Research Has Been With Inorganic EC Materials (WO 3 ) Contrast Ratios > 2:1 in the Thermal IR Shown Polymer EC Materials are Under Study by Numerous Investigators Much Further Development is Needed 18

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 19

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 20

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 Launch Mass Savings (Kg) Chameleon Suit Launch Mass Savings NASA Mars Design Reference Mission ISS Operations Lagrange Point Assembly & Lunar Visit Missions Units Launched Number of 2 Person EVA's / Mission 21

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 22