Presentation on theme: "EVA and Mobility Systems Engineering"— Presentation transcript:
1 EVA and Mobility Systems Engineering Michael RouenRobert C. TrevinoJoe KosmoNASA Johnson Space Center
2 Agenda EVA Challenges for Exploration Space Suit Assembly System RequirementsCardinal ElementsHuman/Robotics & Analog TestingPortable Life SupportNext Generation PLSS Development – Story of a Design EffortLessons LearnedConclusion
3 EVA Challenges for Exploration Robert C. TrevinoNASA 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 conditionsEVA Tools and Mobility AidsEquipment necessary to perform in-space contingency and planetary exploration EVA tasksFor 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 SystemsEquipment necessary to interface the EVA system with the Constellation vehiclesMay include suit mounting equipment, consumable recharge hardware, airlock subsystems, etc.Ground Support SystemsEquipment 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 reconfigurationLightweight, highly mobile suits and dexterous gloves to increase crew productivity, minimize crew injury, and enable long-duration missions and high EVA use ratesEasily sizeable garments to fit a wide range of anthropometric sizesAdvanced life support systems to minimize weight and decrease consumablesAdvanced power systems to minimize weight and increase cycle and shelf lifeAdvanced thermal control to increase crew comfort, decrease consumables, and enable multiple destinationsDust and radiation protective materials and conceptsState 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 ISSConstellation EVA and Crew Survival Capabilities NeededCrew protection and survivability during launch, entry and abort (LEA) scenarios**Apollo Program example: Cabin depressurization protectionZero-gravity EVA capability for In-space Contingency EVA.**Apollo Program example: Return from LEM to CM Contingency EVACEV to LunarLunar Sortie/Outpost/MarsSurface EVA capability for planetary exploration
7 EVA and Suit Systems Interfaces CEVAirlocksOther Constellation VehiclesTools & Mobility AidsRobotic AssistantsPower SystemComm SystemLife SupportSystemThermalSystemRoversHabitatMobilitySystemStructure/MaterialsEnvironmentalProtectionSystemEmergencySystemEarth, In-space & Planetary EnvironmentsGround Support SystemLander■Testing ■ Processing■ Simulators/Analogs■ Trainers■ MCC
9 Human Planetary Surface Exploration Experience When Last Accomplished: 34 Years Ago!Total number of 2-man EVAs14Total Duration of EVAs81 hrs (3.4 days)Average EVA duration6 hrsTotal EVA traverse distance59.6 milesShortest EVA distance.16 miles Apollo 11Longest EVA distance21.9 miles Apollo 17Apollo Mission111214151617Number of EVAs conducted123Duration of EVAs (hrs.) per crewmember18.104.22.1688.620.222.1Total traverse distance (miles)0.161.252.117.416.821.9
10 Design ChallengesEarly 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 includeFor 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-OutSystem VerificationImprove DesignEtc.Long Term TestingPlanetary EVAHabitatEtc.Final GoalLong Term UseReliabilityMaintainability
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 missionsShuttleISSLunar/Mars(1)Recertification5XRedesign20X5 EVA25 EVA300 – 500 EVAMaintenance Goal = 4% of EVA TimeRepair Goal = 1% of EVA TimeNotes: (1) Assumes 2 year mission, EVA every other day
15 Schematic Need Statement EVA ChallengesSchematic Need StatementPLSS Packaging DriverThere are many technology components and system options already in development that may support VSE EVA requirementsShuttle/ISS EMUComponent Weight: 73 lbsPackaging Weight: 79 lbsTotal: 152 lbsMars: lbsPLSS design objectivesFlexible (upgradeable & evolvable)Mission maintainableSmallReliableLightweightRobustNASA 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 ControlVent Flow and Pressure ControlThermal ControlOxygenPowerElectronicsPackaging Concepts
17 Shuttle Extravehicular ChallengesSSA129 lbs.PLSS200 lbs.Total329 lbs.PF: 2.20SSAxxx lbs.PLSS145 lbs.TotalPF: 1.59SSA35 lbs.PLSS65 lbs.Total100 lbs.PF: 1.24Shuttle ExtravehicularMobility UnitMk. III / DO2StudyAdvanced TechnologySpacesuitXX% Reduction inSSA MassXX% Reduction inSSA Mass51% Reduction in PLSSPackaging Factor59% Reduction in PLSSPackaging Factor0% Reduction in PLSSComponent Mass43% Reduction in PLSSComponent MassXX% Reduction in PLSS MaintenanceXX% Reduction in PLSS Maintenance
18 Environmental Challenges to Consider Thermal ControlNeed for coolingNeed for thermal insulationDust MitigationNeed for dust collection and/or removalRadiation ProtectionNeed for human body protection
19 EVA Technologies Needed Environmental ProtectionRadiation protection technologies that protect the suited crewmemberprotection technologies that provide self-sealing capabilitiesDust and abrasion protection materials or technologies to exclude or remove dust, withstand abrasion, and prevent dust adhesionFlexible space suit thermal insulation suitable for use in vacuum and low ambient pressure
20 EVA Technologies Needed Life Support SystemLong-life and high capacity chemical oxygen storage systems for an emergency supply of oxygen for breathingLow-venting or non-venting regenerable individual life support subsystem concepts for crewmember cooling, heat rejection, and removal of expired water vapor and CO2Lightweight convection and freezable radiators for thermal controlInnovative garments that provide direct thermal control to crewmembersCO2 and humidity control devices that, while minimizing expendables function in CO2 environment
21 EVA Technologies Needed Sensors, Communications, Cameras, and Informatics SystemsSpace suit mounted displays for use both inside and outside the space suitCO2, biomed, radiation monitoring, and core temperature sensors with reduced size, lightweight, increased reliability, decreased wiring, and packaging flexibilityLightweight sensors systems that detect N2, CO2, NH4, O2, ammonia, hydrazine partial pressures
22 EVA Technologies Needed EVA MobilitySpacesuit low profile bearings for partial gravity mobility requirements and are lightweightIntegrationMinimum gas loss airlocks providing quick exit and entryEVA Navigation and LocationSystems and technologies for providing an EVA crewmember real-time navigation and position information while traversing on foot or a rover.
23 Space Suit AssemblyEnhancing the Capabilities of Space-Suited Planetary Surface CrewmembersPotential Application of SOA & Emerging TechnologiesInformation 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 walkingNo dust control/protectionChest-mounted display degrades arm/hand work envelop and foot visibilityThermal protection (vacuum environments only) is too bulky, thus impeding mobility and glove dexterity/tactilityPLSS consumables require frequent replenishment or time & power to re-chargeSpacesuit and PLSS not totally serviceable by astronauts24
25 Generic EVA System Needs Space Suit SystemProtection from hazards of new mission environmentAppropriate pressure to eliminate “bends” risk & pre-breathe requirementsLong-term durability & reliability to function over mission life cycleMinimize weight and bulkSimple re-sizing capability to accommodate various ranges of anthropometryHigh degree of mobility & comfortProvisions to accommodate & interface ancillary support elements (cooling garment, bio-sensors, communications system, PLSS, etc.)Accommodate mission vehicle interface requirementsPortable Life Support SystemMinimize use of expendables (water, oxygen, power)Provide high level of reliability & safetyMinimize weight & volume by efficient component packagingProvide ease of maintenance & repair during the missionMaintain 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 system25
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 tasksMandatory for center-of-gravity controlMandatory for ingress/egress airlocks and rovers (seated position)Goal ; achieve near shirtsleeve range with low force required to reduce fatigueROBUSTNESS:DURABILITY/LONG SERVICEABLE LIFEHigh mission cycle life capability for multiple EVA’s (daily operations)Abrasion/dust resistanceImpact/tear resistanceIncorporate long-term shelf-life/operational-life materialsWEARABILITYDon/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 impactSIMPLICITY:Reduce system element complexity (incorporate modularity)Ease of maintenance & repair26
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 tasksMandatory for center-of-gravity controlMandatory for ingress/egress airlocks and rovers (seated position)Goal ; achieve near shirtsleeve range with low force required to reduce fatigueROBUSTNESS:DURABILITY/LONG SERVICEABLE LIFEHigh mission cycle life capability for multiple EVA’s (daily operations)Abrasion/dust resistanceImpact/tear resistanceIncorporate long-term shelf-life/operational-life materialsWEARABILITYDon/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 impactSIMPLICITY:Reduce system element complexity (incorporate modularity)Ease of maintenance & repair27
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 integrationOn-suit computer and advanced informatics systems for voice-video-data transmissionEVA traverse mapping and route planning displays w/obstacle and hazards avoidance alertsEVA 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 robots28
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 levelsGeologic/astrobiological samplingTactile feed-backHelmet-mounted interactive “hand’s-free” visual display & voice activation systems:Capability for system monitoring and control functions; “real-time” contentAutonomous 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 levelAdaptive 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 bookAutonomous system for EVA equipment monitoring, trend analysis, “self-diagnostics”, and malfunction response applicable to:Life support system, airlock, rovers, robotic agentsSmall, low-power, high intensity portable & suit-mounted lighting systemsUltra Wide Band (UWB) communications system integrating voice, video, and data transmission capability29
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 exercisesFor the future of space exploration, human/robotic interactive testing in a representative planetary environment is essential for proper development of specific technologies, & integrated operationsProvides the capability to validate experimental hardware/software, mission operational techniques & identify & establish technical requirements applicable for future planetary explorationCurrently, 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 Testing1999: EVA Robotic Assistant (ERA)2002: Enhancement of human/robotic interaction with the Geological science trailer and the EVA Information pack2003: USGS 1-G Lunar Rover Training Vehicle, 2nd Gen. science trailer and EVA Info. Pack2004: Human/robot system evaluation of EVA informatics technologies & user interfaces, assessment of the electric tractor & Chariot functional performance characteristics2005: Demonstrate large mass transport & handling, SCOUT systems evaluations2006: “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 2006ESMD Surface MobilityDevelopment and demonstration of combined robot (ATHLETE, Centaur, SCOUT, and K-10) and two suited crewmember planetary activities in an appropriate terrestrial environmentSCOUTTo 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 systemTo test advanced technologies that may prove useful in future SCOUT or planetary/Lunar rover development projectsSCOUT/Suit Objectives:Evaluate cockpit designEvaluate on-board suit rechargeEvaluate 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 SupportMichael RouenAdvanced 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.FunctionProtect, 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.
37 GoalSeek 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 Mass30405060708090100110PLSS Total Mass100#95#90#85#80#75#70#65#60#Component Mass, lbTarget22.214.171.124.126.96.36.199.81.92Mass 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 massNeed to reduce suit system mass by 2/3 or limit the work day.Mass or Weight? Which is the concern?MassWeightEARTH150 lbm = 68 kg150 lbf = 667 NMARS57 lbf = 253 N
40 Evaluation & Mock-upDecision 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 evaluateflexibility for technology changeIn-use maintenance
42 Mass Reduction Techniques 1) Breakthrough design conceptsExamples are: the gasbag outer cover, the combined base plate / hatch with through bolt mounted LRU’s.2) Detail part weight optimizationThis 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 areaThis 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 phaseSame 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.ProductsDesign 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.