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EVA and Mobility Systems Engineering

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Presentation on theme: "EVA and Mobility Systems Engineering"— Presentation transcript:

1 EVA and Mobility Systems Engineering
Michael Rouen Robert C. Trevino Joe Kosmo NASA Johnson Space Center

2 Agenda EVA Challenges for Exploration Space Suit Assembly
System Requirements Cardinal Elements Human/Robotics & Analog Testing Portable Life Support Next Generation PLSS Development – Story of a Design Effort Lessons Learned Conclusion

3 EVA Challenges for Exploration
Robert C. Trevino NASA JSC

4 EVA Systems Content Suit Systems EVA Tools and Mobility Aids
Life support systems and pressure garments required to protect crewmembers from ascent/entry, in-space, and planetary environmental conditions EVA Tools and Mobility Aids Equipment necessary to perform in-space contingency and planetary exploration EVA tasks For CEV contingency EVA, may include drives, ratchets, sockets, restraint equipment, etc. For planetary exploration, may include drills, hammers, walking sticks, geological test equipment, etc. For planetary exploration, may include rovers, “assistant” robots, etc. Vehicle Support Systems Equipment necessary to interface the EVA system with the Constellation vehicles May include suit mounting equipment, consumable recharge hardware, airlock subsystems, etc. Ground Support Systems Equipment and facilities required to test and verify EVA development and flight systems

5 EVA Suit Technology Challenges
Flexible, open architecture which can support multi-use and multi-destination operations with minimal system reconfiguration Lightweight, highly mobile suits and dexterous gloves to increase crew productivity, minimize crew injury, and enable long-duration missions and high EVA use rates Easily sizeable garments to fit a wide range of anthropometric sizes Advanced life support systems to minimize weight and decrease consumables Advanced power systems to minimize weight and increase cycle and shelf life Advanced thermal control to increase crew comfort, decrease consumables, and enable multiple destinations Dust and radiation protective materials and concepts State of the art communications and computing capability for multi-media crew-ground interaction (e.g., integrated communications, high tech information systems, and heads-up displays) Integrated human-robotic work capability to increase safety, efficiency, & productivity

6 Constellation EVA and Crew Survival Capabilities Needed
CEV to ISS Constellation EVA and Crew Survival Capabilities Needed Crew protection and survivability during launch, entry and abort (LEA) scenarios **Apollo Program example: Cabin depressurization protection Zero-gravity EVA capability for In-space Contingency EVA. **Apollo Program example: Return from LEM to CM Contingency EVA CEV to Lunar Lunar Sortie/Outpost/Mars Surface EVA capability for planetary exploration

7 EVA and Suit Systems Interfaces
CEV Airlocks Other Constellation Vehicles Tools & Mobility Aids Robotic Assistants Power System Comm System Life Support System Thermal System Rovers Habitat Mobility System Structure/ Materials Environmental Protection System Emergency System Earth, In-space & Planetary Environments Ground Support System Lander ■Testing ■ Processing ■ Simulators/Analogs ■ Trainers■ MCC

8 Historical perspectives
Pressure (emergency only) Umbilical only pressure suit Autonomous Surface pressure suit Simplified Apollo PAST Mercury Gemini Apollo Skylab Launch, entry suit Autonomous 0-G EVA Orlan (rear entry) Launch, entry suit PRESENT Shuttle ACES Shuttle/ISS EMU ISS Russian Orlan Russian Sokol Soft upper body joints Hard/Soft Hybrid w/multi-axis mobility joints Soft, lightweight FUTURE D Suit I Suit H Suit

9 Human Planetary Surface Exploration Experience
When Last Accomplished: 34 Years Ago! Total number of 2-man EVAs 14 Total Duration of EVAs 81 hrs (3.4 days) Average EVA duration 6 hrs Total EVA traverse distance 59.6 miles Shortest EVA distance .16 miles Apollo 11 Longest EVA distance 21.9 miles Apollo 17 Apollo Mission 11 12 14 15 16 17 Number of EVAs conducted 1 2 3 Duration of EVAs (hrs.) per crewmember 2.8 7.8 9.4 18.6 20.2 22.1 Total traverse distance (miles) 0.16 1.25 2.1 17.4 16.8 21.9

10 Design Challenges Early experiences with pressure suits on Gemini, Mercury and Apollo, along with non-existent Shuttle suit requirements in the programs early stages, led to the dual pressure suit approach that currently supports the Shuttle program. The Advanced Crew Escape Suit (ACES) and the Extravehicular Mobility Unit (EMU) have served as the crew escape and extravehicular activity (EVA) pressure suits for quite some time. The EMU, over 25 years old and facing significant obsolescence issues, is not compatible with the planetary environments of either the Moon or Mars and does not support the logistical requirements of long term missions. The ACES was not designed to perform EVAs. The Russian Orlan and Sokol, while slightly varied in design, have many of the same limitations. To support the Vision for Space Exploration (VSE) and Constellation objectives, it is necessary to develop a new pressurized suit system. One that is smart and evolvable.

11 Design Challenges (1 vs 2 vs 3 suits…)
The broad range of operational environments that this new suit system will be required to support poses some new challenges in selecting and designing the appropriate suit architecture. However, the potential programmatic benefits of developing, operating and sustaining a common/evolvable single suit system architecture warrant a more thorough examination. Development of a single integrated IVA/EVA suit system that satisfies all of the Constellation capability requirements versus a multiple suit approach is a programmatic decision that is at the forefront of the Exploration pressure suit development activity.

12 Design Challenges (1 vs 2 vs 3 suits…)
Some basic design challenges that need to be examined include For IVA un-pressurized periods, the suit needs to support the crew for long periods of time (i.e. launch/entry/abort and in-flight powered phases). These phases alone would lean towards a lightweight, low-bulk, all fabric-based garment structure, minimizing hard-contact points. For EVA, more gross mobility is necessary to support planetary exploration. For surface EVA alone, this would lean towards a more rigid, high bulk suit for operating in an upright position but could be uncomfortable to wear in a recumbent position as necessary for IVA phases.

13 The overall NASA goal is to get to Mars by using LEO and Lunar missions as stepping stones
Initial Prove-Out System Verification Improve Design Etc. Long Term Testing Planetary EVA Habitat Etc. Final Goal Long Term Use Reliability Maintainability

14 Maintenance Goal = 4% of EVA Time Repair Goal = 1% of EVA Time
The number of EVA’s between overhauls will need to significantly increase in order to support future missions Shuttle ISS Lunar/Mars(1) Recertification 5X Redesign 20X 5 EVA 25 EVA 300 – 500 EVA Maintenance Goal = 4% of EVA Time Repair Goal = 1% of EVA Time Notes: (1) Assumes 2 year mission, EVA every other day

15 Schematic Need Statement
EVA Challenges Schematic Need Statement PLSS Packaging Driver There are many technology components and system options already in development that may support VSE EVA requirements Shuttle/ISS EMU Component Weight: 73 lbs Packaging Weight: 79 lbs Total: 152 lbs Mars: lbs PLSS design objectives Flexible (upgradeable & evolvable) Mission maintainable Small Reliable Lightweight Robust NASA must determine the optimum combination of these life support technologies (i.e., a functional support schematic) that meets the mission requirements

16 Technology Options to Consider
CO2/Humidity Control Vent Flow and Pressure Control Thermal Control Oxygen Power Electronics Packaging Concepts

17 Shuttle Extravehicular
Challenges SSA 129 lbs. PLSS 200 lbs. Total 329 lbs. PF: 2.20 SSA xxx lbs. PLSS 145 lbs. Total PF: 1.59 SSA 35 lbs. PLSS 65 lbs. Total 100 lbs. PF: 1.24 Shuttle Extravehicular Mobility Unit Mk. III / DO2 Study Advanced Technology Spacesuit XX% Reduction in SSA Mass XX% Reduction in SSA Mass 51% Reduction in PLSS Packaging Factor 59% Reduction in PLSS Packaging Factor 0% Reduction in PLSS Component Mass 43% Reduction in PLSS Component Mass XX% Reduction in PLSS Maintenance XX% Reduction in PLSS Maintenance

18 Environmental Challenges to Consider
Thermal Control Need for cooling Need for thermal insulation Dust Mitigation Need for dust collection and/or removal Radiation Protection Need for human body protection

19 EVA Technologies Needed
Environmental Protection Radiation protection technologies that protect the suited crewmember protection technologies that provide self-sealing capabilities Dust and abrasion protection materials or technologies to exclude or remove dust, withstand abrasion, and prevent dust adhesion Flexible space suit thermal insulation suitable for use in vacuum and low ambient pressure

20 EVA Technologies Needed
Life Support System Long-life and high capacity chemical oxygen storage systems for an emergency supply of oxygen for breathing Low-venting or non-venting regenerable individual life support subsystem concepts for crewmember cooling, heat rejection, and removal of expired water vapor and CO2 Lightweight convection and freezable radiators for thermal control Innovative garments that provide direct thermal control to crewmembers CO2 and humidity control devices that, while minimizing expendables function in CO2 environment

21 EVA Technologies Needed
Sensors, Communications, Cameras, and Informatics Systems Space suit mounted displays for use both inside and outside the space suit CO2, biomed, radiation monitoring, and core temperature sensors with reduced size, lightweight, increased reliability, decreased wiring, and packaging flexibility Lightweight sensors systems that detect N2, CO2, NH4, O2, ammonia, hydrazine partial pressures

22 EVA Technologies Needed
EVA Mobility Spacesuit low profile bearings for partial gravity mobility requirements and are lightweight Integration Minimum gas loss airlocks providing quick exit and entry EVA Navigation and Location Systems and technologies for providing an EVA crewmember real-time navigation and position information while traversing on foot or a rover.

23 Space Suit Assembly Enhancing the Capabilities of Space-Suited Planetary Surface Crewmembers Potential Application of SOA & Emerging Technologies Information Provided by: Joe Kosmo, JSC

24 Limitations of Existing EVA Architecture
The mass & mobility of current Shuttle/ISS space suit is not acceptable for use in a partial gravity environment due to the following: Not capable of kneeling, bending, or prolonged walking No dust control/protection Chest-mounted display degrades arm/hand work envelop and foot visibility Thermal protection (vacuum environments only) is too bulky, thus impeding mobility and glove dexterity/tactility PLSS consumables require frequent replenishment or time & power to re-charge Spacesuit and PLSS not totally serviceable by astronauts 24

25 Generic EVA System Needs
Space Suit System Protection from hazards of new mission environment Appropriate pressure to eliminate “bends” risk & pre-breathe requirements Long-term durability & reliability to function over mission life cycle Minimize weight and bulk Simple re-sizing capability to accommodate various ranges of anthropometry High degree of mobility & comfort Provisions to accommodate & interface ancillary support elements (cooling garment, bio-sensors, communications system, PLSS, etc.) Accommodate mission vehicle interface requirements Portable Life Support System Minimize use of expendables (water, oxygen, power) Provide high level of reliability & safety Minimize weight & volume by efficient component packaging Provide ease of maintenance & repair during the mission Maintain normal range of physiological aspects of crew during wide range of metabolic activities (O2 level, CO2 level, ventilation flow-rates, temperature conditions) Provide integration capability with spacesuit system 25

26 Cardinal Elements of a Planetary Surface Spacesuit
MOBILITY: Mandatory for walking (EVA traverses) and for negotiating rough terrain (rock fields, slopes, gullies) Mandatory for EVA tasks, geologic exploration, deployment of surface equipment , maintenance & repair tasks Mandatory for center-of-gravity control Mandatory for ingress/egress airlocks and rovers (seated position) Goal ; achieve near shirtsleeve range with low force required to reduce fatigue ROBUSTNESS: DURABILITY/LONG SERVICEABLE LIFE High mission cycle life capability for multiple EVA’s (daily operations) Abrasion/dust resistance Impact/tear resistance Incorporate long-term shelf-life/operational-life materials WEARABILITY Don/doff use (daily operations over long mission periods) Handling capability (cleaning/storage) LIGHTWEIGHT: Reduce crewmember fatigue (assisted by low Lunar & Mars gravity) Mass handling control (primarily “on-back” carry weight - - PLSS) Reduce mission launch cost impact SIMPLICITY: Reduce system element complexity (incorporate modularity) Ease of maintenance & repair 26

27 Cardinal Elements of a Planetary Surface Spacesuit
MOBILITY: Mandatory for walking (EVA traverses) and for negotiating rough terrain (rock fields, slopes, gullies) Mandatory for EVA tasks, geologic exploration, deployment of surface equipment , maintenance & repair tasks Mandatory for center-of-gravity control Mandatory for ingress/egress airlocks and rovers (seated position) Goal ; achieve near shirtsleeve range with low force required to reduce fatigue ROBUSTNESS: DURABILITY/LONG SERVICEABLE LIFE High mission cycle life capability for multiple EVA’s (daily operations) Abrasion/dust resistance Impact/tear resistance Incorporate long-term shelf-life/operational-life materials WEARABILITY Don/doff use (daily operations over long mission periods) Handling capability (cleaning/storage) LIGHTWEIGHT: Reduce crewmember fatigue (assisted by low Lunar & Mars gravity) Mass handling control (primarily “on-back” carry weight - - PLSS) Reduce mission launch cost impact SIMPLICITY: Reduce system element complexity (incorporate modularity) Ease of maintenance & repair 27

28 Human/Machine Interactive & Sensory Capabilities
Voice and gesture actuation and command of EVA robotic assistant vehicles & systems “Head’s up” helmet-mounted information display systems for space suit integration On-suit computer and advanced informatics systems for voice-video-data transmission EVA traverse mapping and route planning displays w/obstacle and hazards avoidance alerts EVA robotic assistants w/manipulator arms and end-effectors that can be remotely teleoperated “Smart” sensor systems for geologic sampling or environmental monitoring by humans or robots 28

29 Intelligence Enhancement Concepts “Smart Spacesuit”
Portable or suit/glove-mounted miniature, low-power environmental monitoring sensors: External environment – radiation, UV levels, electromagnetic fields, contamination levels Geologic/astrobiological sampling Tactile feed-back Helmet-mounted interactive “hand’s-free” visual display & voice activation systems: Capability for system monitoring and control functions; “real-time” content Autonomous terrain EVA traverse path mapping, navigation and crew tracking system: Target recognition to include specified “land marks” or “science stations” and obstacle/hazards avoidance based on development of localized 3-D topographic map with appropriate “over-lays” Non-invasive, low-power, wireless, oxygen compatible, medical/physiological sensors: Blood N2, ECG, CO2, body-core temperature, muscle fatigue level Adaptive collaborative system for documenting, recording, labeling, cataloguing and retrieval of EVA collected science data: Geology/astrobiology science samples, photos, video, technical notes, etc. - - “smart” field data-log book Autonomous system for EVA equipment monitoring, trend analysis, “self-diagnostics”, and malfunction response applicable to: Life support system, airlock, rovers, robotic agents Small, low-power, high intensity portable & suit-mounted lighting systems Ultra Wide Band (UWB) communications system integrating voice, video, and data transmission capability 29

30 Current Analog Testing Efforts
Desert Research and Technology Studies (started in 1997) Desert “RATS” is a combined group of inter-NASA center scientists & engineers, collaborating with representatives of industry and academia, for the purpose of conducting remote field exercises For the future of space exploration, human/robotic interactive testing in a representative planetary environment is essential for proper development of specific technologies, & integrated operations Provides the capability to validate experimental hardware/software, mission operational techniques & identify & establish technical requirements applicable for future planetary exploration Currently, D-RATS remote field testing is being conducted in high desert areas adjacent to Flagstaff, Arizona & “dry-run” tests conducted at JSC

31 EVA Human/Robotic Testing
DRATS first started human/robotic testing in 1999 with the Astronaut/Rover (ASRO) Study of human/robot interactive tests & investigating the division of labor between human & robot for planetary EVA exploration operations

32 EVA Human/Robotic Testing
Human/Robotic DRATS Testing 1999: EVA Robotic Assistant (ERA) 2002: Enhancement of human/robotic interaction with the Geological science trailer and the EVA Information pack 2003: USGS 1-G Lunar Rover Training Vehicle, 2nd Gen. science trailer and EVA Info. Pack 2004: Human/robot system evaluation of EVA informatics technologies & user interfaces, assessment of the electric tractor & Chariot functional performance characteristics 2005: Demonstrate large mass transport & handling, SCOUT systems evaluations 2006: “Day-in-the-life” EVA Crewmember tasks, regolith excavation, demonstration of combined robots (ATHLETE, Centaur, SCOUT, and K-10 w crewmembers

33 EVA Human/Robotic Testing
Human/Robotic DRATS Testing 2006 ESMD Surface Mobility Development and demonstration of combined robot (ATHLETE, Centaur, SCOUT, and K-10) and two suited crewmember planetary activities in an appropriate terrestrial environment SCOUT To test the SCOUT vehicle while being driven by an onboard operator, a tele-operator at a remote location (base camp, ACES, ExPOC), and an autonomous system To test advanced technologies that may prove useful in future SCOUT or planetary/Lunar rover development projects SCOUT/Suit Objectives: Evaluate cockpit design Evaluate on-board suit recharge Evaluate Communications, Avionics, and Informatics Pack (CAI-pack) system, functions, and user interaction

34 Michael Rouen Advanced PLSS Design Effort to Reduce Weight and Volume
Portable Life Support Michael Rouen Advanced PLSS Design Effort to Reduce Weight and Volume

35 PLSS Packaging Definition Function
Any item performing a major, useful life support function is a component to be packaged and is not packaging. Harnesses, connectors, switches, brackets, wiring, and plumbing are packaging. Structure is packaging, even in such special cases as the Shuttle valve module housing. Function Protect, Connect and Hold the PLSS and its components together internally and externally while providing access to PLSS components internally for maintenance and for technology change without extensive redesign impact.

36 Weight Pareto for STS PLSS & SOP

37 Goal Seek ways to reduce the weight (mass) of PLSS packaging, and at the same time, develop a packaging scheme that would make PLSS technology changes less costly than the current packaging methods.

38 Packaging Dynamic Target Component Mass, lb 1 1.1 1.2 1.3 1.4 1.5 1.6
Interaction of Packaging Factor, Functional Component Mass and PLSS Total Mass 30 40 50 60 70 80 90 100 110 PLSS Total Mass 100# 95# 90# 85# 80# 75# 70# 65# 60# Component Mass, lb Target 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 Mass Packaging Factor

39 Mass Management: Mass vs. Weight
People on Mars will condition to Martian gravity. So, people on Mars can only carry the same mass they can carry on Earth. Backpacker’s rule % of person’s lean body mass for a full day. Current suit system = the person’s mass Need to reduce suit system mass by 2/3 or limit the work day. Mass or Weight? Which is the concern? Mass Weight EARTH 150 lbm = 68 kg 150 lbf = 667 N MARS 57 lbf = 253 N

40 Evaluation & Mock-up Decision Matrix Method Evaluation to identify weak and strong points of each concept to guide future work. The lightest weight concept was selected for further work & a mock up was included in the plan to validate the concept and to assure the concept was indeed realizable. The mockup will be used to evaluate flexibility for technology change In-use maintenance

41 Lessons Learned 3 2 1 2 3 4 5 VPF vs. MPF Frequent Overhauls
Specialized Designs Optimized Designs Flexible Designs A monument Long-term Use 3 Shuttle EMU (2.3, 2.2) Mass Packaging Factor 2 Apollo (3.0, 1.7) Orlan (3.1, 1.5) NASA (2.9,1.3) 1 2 3 4 5 Volume Packaging Factor Disposable Monuments Difficult to Maintain Technology Specific Mission Specific Modular Easy to Maintain Technology Adaptable Mission Adaptable Fewer Overhauls

42 Mass Reduction Techniques
1) Breakthrough design concepts Examples are: the gasbag outer cover, the combined base plate / hatch with through bolt mounted LRU’s. 2) Detail part weight optimization This technique involves tradeoffs, material selection, changing requirements, reducing wall thickness, etc. This needs to be done for every detail part in greatest weight order. 3) Minimizing volume and surface area This technique became obvious in this effort. The volume and surface area contributes to the overall mass.

43 Design Tools During the concept phase During the detail design phase
Pro-e® and Mechanica® used to rough out the concept. Important to keep the modeling simple, Mechanica stress analysis for stress in major structural members, Local stress concentrations worked during the detail design. Mathcad® for automation of trade study iterations. MS EXCEL® spreadsheets for bookkeeping tasks. Dytran® for the non-linear analysis of the fall cases. During the detail design phase Same tools used in more depth. Possibly NASTRAN® instead of Mechanica for analysis in some situations. Nastran more versatile but demands more training. SINDA® used for thermal analysis.

44 Lessons Learned Spend the time to get the concept right up front.
The more detailed the concept or design gets before it is found to be unacceptable, the more costly will be the recovery effort. Prove out a new idea/concept with first cut analysis unless, The basic concept depends on a unique idea – then a test must be run before concept approval. In the conception phase the program needs experienced, inventive, engineers that won’t get bogged down in detail that is not needed until later in the process.

45 Lessons Learned The weight target is very difficult to meet.
Develop a weight control plan early with estimated or calculated weights so that corrective actions can be taken as soon as possible. The concepts generated resulted in unacceptably high component operating temperatures. Thermal analysis personnel available early in the concept phase. Complexity of the heat transfer within PLSS prevents designer from doing own analysis. Document the importance of the key requirements and re-evaluate periodically. We lost sight of the weight goal even though that was the primary reason for the entire effort.

46 PLSS Development Conclusions & Products
Removing 2/3 of the PLSS mass is as hard as we expected. Creativity is still needed. Requirements conflict strongly in the problem. Significant progress has been made - but, the concept requires further development. Products Design guideline document created in Task Two. Extensive documentation of effort; contains proven procedures and design and analysis tools. Concept Mockup

47 EVA Engineering Conclusion
The space suits and EVA systems needed to meet the requirements for sustainable and extended Lunar exploration present new challenges to NASA, other government agencies, academia, and industry. Innovative technologies and cooperation among the many involved organizations to address these challenges will be one of the keys to success for future space exploration. 

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