1 NASA Institute for Advanced Concepts Contract # 07600-067 A Chameleon Suit to Liberate Human Exploration of Space Environments Final Report December, 2001 Edward W. Hodgson Jr. Hamilton Sundstrand Space Systems International 2 Table of Contents Introduction ................................................................................................................................... 5 Summary........................................................................................................................................ 7 Concept Analysis ........................................................................................................................... 9 Concept Description and Analysis Approach........................................................................................9 Mission Requirements.........................................................................................................................11 Feasibility Assessment ........................................................................................................................16 Design Analyses and Component Requirements.................................................................................20 Human Interface Implications .............................................................................................................23 Concept Refinement and Evolution...........................................................................................32 Surface Utilization & Internal Heat Transport ....................................................................................32 Thermal Contact Enhancement ...........................................................................................................33 Directional Surface Shading................................................................................................................37 Potential Concept Growth ...................................................................................................................40 System Control and Electronic Integration.............................................................................. 44 Control objectives and technical basis ................................................................................................44 Control zones.......................................................................................................................................45 Control Sensor Interfaces ....................................................................................................................47 Control architecture alternatives and trade-offs ..................................................................................49 Signal Flow and Power Distribution ...................................................................................................50 Effector Drive and Control..................................................................................................................51 Technology Readiness, Development Needs and Outlook.......................................................52 Enabling technologies definition and required characteristics ............................................................52 Variable geometry insulation activation..............................................................................................54 Vacuum thermal contact technologies.................................................................................................55 Infra-red variable emissivity materials................................................................................................57 Wearable sensing and control systems ................................................................................................59 Potential Benefits to NASA Missions......................................................................................... 61 Benefits estimation methodology ........................................................................................................61 Estimated quantitative benefits............................................................................................................61 Other considerations............................................................................................................................64 Conclusions .................................................................................................................................. 66 Acknowledgements...................................................................................................................... 67 References .................................................................................................................................... 68 3 List of Figures Figure 1. HEDS Missions will demand revolutionary thermal control solutions......................................................... 5 Figure 2. Both physical and electro-optical control will modulate space suit insulation. ............................................. 9 Figure 3. Local control of insulation properties supports operation in any environment without constraining activities .............................................................................................................................................................................. 9 Figure 4. The proposed system concept responds actively to wearer activities and changing environments to maintain thermal comfort.................................................................................................................................... 10 Figure 5. A representative EVA mission design reference metabolic rate profile ...................................................... 13 Figure 6. Maximum Radiated Heat Load From PLSS Area ....................................................................................... 16 Figure 7. Maximum Radiated Heat Load From Spacesuit Surface Area .................................................................... 17 Figure 8. Maximum Radiated Heat Load From Combined PLSS and Pressurized Suit Area.................................... 18 Figure 9. Adiabatic equilibrium temperature for lunar and suit surfaces exceed skin temperature at many sun elevation angles................................................................................................................................................... 19 Figure 10. Operation in lunar craters near midday will require directional shading on active radiating portions of the suit....................................................................................................................................................................... 20 Figure 11. Expanded Suit Layers for Maximum Insulation....................................................................................... 21 Figure 12. Collapsed Suit Layers for Maximum Heat Rejection ............................................................................... 22 Figure 13. Comfortable human average skin temperature falls with increasing activity. ...........................................25 Figure 14. Body core temperature is regulated to increase slightly with increasing work rate. (Reference 5) ........... 26 Figure 15. Shivering is triggered by cold skin temperatures and suppressed by warm core temperature. (Reference 8) ......................................................................................................................................................................... 27 Figure 16. Thermal gradients within the body result in varying source temperature and heat transport requirements for different parts of the Chameleon Suit. (Reference 13) ................................................................................. 28 Figure 17. Hypothalamus (Reference 16) .................................................................................................................. 28 Figure 18. Simplified Representation of Thermoregulation (Reference 17)............................................................... 29 Figure 19: Vasoconstriction and Vasodilation of Vessels (Reference 21).................................................................. 31 Figure 20. The EVA life support system backpack can interfere with heat rejection from the suit surface or offer additional heat rejection opportunities. ............................................................................................................... 32 Figure 21. Thermal contact resistance at low contact pressures is a significant challenge for Chameleon Suit implementation.................................................................................................................................................... 34 Figure 22. Fibrous carbon felts can provide substantially improved thermal contact between layers in the Chameleon Suit. ..................................................................................................................................................................... 35 Figure 23. Effective heat transfer is achieved at low contact pressure........................................................................ 35 Figure 24. The Chameleon Suit layer structure is compatible with the use of thermal contact enhancement. .......... 36 Figure 25. The use of thermally conductive felt interfaces to improve maximum Chameleon Suit heat transmission slightly reduces radiated heat loss control authority. .........................................................................................