Source of AcquisitionNASA Johnson Space Center

HUMAN FACTORS AND THE INTERNATIONAL SPACE STATION

Brian Peacock, Sudhakar Rajulu, Jennifer NovakNational Space Biomedical Research Institute,

Houston, TexasThomas Rathjen, Mihriban Whitmore, James Maida, Barbara WoolfordNational Aeronautics and Space Administration, Johnson Space Center,

Houston, Texas

The purposes of this panel are to inform the human factors communityregarding the challenges of designing the International Space Station (ISS)and to stimulate the broader human factors community into participatingin the various basic and applied research opportunities associated with theISS. This panel describes the variety of techniques used to plan andevaluate human factors for living and working in space. The panelmembers have contributed to many different aspects of the ISS design andoperations. Architecture, equipment, and human physical performancerequirements for various tasks have all been tailored to the requirements ofoperating in microgravity.

INTRODUCTION

The NASA space human factors community(SHFE) has the responsibility of contributing to thedesign and operation of current and future spacevehicles. NASA also supports advanced humanfactors research and development. The tools thatNASA uses to identify and prioritize human factorsresearch needs are the Space Human FactorsEngineering project plan and the BioastronauticsCritical Path Roadmap. Human factors knowledgeis communicated in terms of engineeringrequirements via the NASA-STD-3000 document.

The project plan and the complementary annualimplementation plan address the spectrum of humanfactors research, development and implementationactivities covering physical, cognitive,psychosocial, environmental and systems factors.The human factors component of the critical pathroadmap addresses those questions that need to beanswered before long duration exploration missionscan be undertaken. As in most large organizationshuman factors personnel in NASA interact withengineering, operations, training and medicalfunctions in a generally seamless way. Similarly,NASA human factors research activity overlapswith a wide variety of disciplines includingmedicine, psychology and engineering.

The activities of the NASA space humanfactors engineering function are monitored andguided by a Science and Technology WorkingGroup (STWG) which consists of broad humanfactors expertise from academia, the military,industry and consulting organizations. These currentoperations include support for International SpaceStation and the Shuttle for construction,maintenance and scientific research. In particularthe NASA SHFE personnel address acoustics,vision systems, interior volume control, stowageand waste, inventory management, food systemsand performance of the multicultural crew. Theadvanced research and development activities aredriven by the challenges of exploration classmissions which are characterized by: extendedduration in a micro gravity environment, limitedcommunications, minimal or no re-supply and theever present hostile space environment.

PHYSICAL PERFORMANCE

The macro spatial design of the ISS isconstrained by the challenges of carrying thevarious modules into orbit in the Shuttle cargo bay.Given these constraints the human factors andhabitability specialists at NASA apply thetechniques of anthropometry, biomechanics andtask analysis to the design of the spatial and

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operational environment. The astronaut populationis relatively small in number and theAnthropometry and Biomechanics Facility (ABF)routinely takes a full set of anthropometric andstrength measures of all astronaut applicants.Recently these measures have been supplementedby frill body scanning of most of the currentastronauts. These precise spatial and strengthmeasures are essential for both design and safety.The microgravity environment results in spinalelongation and body shape changes due to fluidshift. These changes are important in the design ofExtra Vehicular Activity (EVA) suits as well asshuttle transfer facilities.

Strength Capabilities

Crewmember mobility and force outputcapability is limited by EVA clothing and isaffected in several ways by the lack of gravity. Acombination of lack of ground reaction forces andthe need to wear hard shell-type suits changes thecapabilities and limitations of humans in space.Hence, strength capabilities of humans areconsiderably different in space and areunfortunately not comparable or analogous tohuman strength data from an earth gravityenvironment. In addition, crewmembers arerequired to perform certain unique tasks such assatellite retrieval or transport heavy masses inspace. There are no analogous tasks in a 1-genvironment that can be easily modified tounderstand how humans would be limited whileperforming such micro-g specific tasks. Hence, theABF has been conducting research to gather data(Rajulu et al., 1994, Rajulu, et al., 1993; Rajulu,1999) and to develop anthropometric andbiomechanical models (Rajulu and Klute, 1992;Gonzalez et al., 2001) for micro- and partial gravityenvironments. These models can be applied to theprediction of performance capabilities under microand low gravity conditions and with alternativedesigns of EVA suits, hardware, and work practices.Effective use is made of micro gravity simulatorssuch as the frictionless surface simulator and theKC 135 airplane. This "vomit comet" performs aseries of climbs and dives providing up to 25seconds of zero g and 2 g conditions.

Physical Restraints and Mobility Aids

The micro gravity environment presentsproblems of postural stability while crew membersperform either high force tasks or precise tasks aswith glove boxes. The maintenance of anappropriate posture for extended time periods canlead to fatigue and a decrement in performancecapability. Strategically placed restraints andmobility aids, such as foot restraints or hand railsare key to both the maintenance of comfortablepostures and for exerting the higher forces neededto manipulate and transfer large mass objects suchas racks. The human factors community has beenintimately involved with task analysis, equipmentand restraint design to facilitate such micro gravitytasks. The involvement of the human factorscommunity was so appreciated by the crewmembers that they presented Dr Whitmore with theprestigious Snoopy award for her contributions.

A series of ergonomic evaluations of existingShuttle and potential ISS crew restraints wasconducted to identify the human factorsrequirements for crew restraint design specificallyfor use with the glove boxes (Whitmore, McKayand Mount, 1995). The experimental work on thesestudies included video analysis of working posture,human modeling analysis, and a compilation ofcrew comments and questionnaire responses. Themost significant accomplishment of this effort wasdetermining the need for two- (optional three-)point restraining of crew in order to accommodatecomfortable crew posture and repetitive, fine motortask control performance in micro gravity. Theother significant guidelines were simplicity,stability, flexibility, and easy ingress/egress. Aconcept with two-point restraining used for therobotic operations onboard the Shuttle was modifiedand used at the glove box. Currently, this modifiedtwo-point crew restraint is being used for all therobotic operations during the ISS assemblymissions. In addition, findings and lessons learnedfrom these evaluations have been provided to thedevelopers for two concepts that are beingdeveloped one for the ISS robotics operations in theCupola, a module being developed by one of theInternational Partners, and one for the Life SciencesGlovebox, a payload module. These ergonomicsevaluations not only contributed to the design of

more effective and safe crew restraints for confinedworkstations but also helped promote the awarenessof ergonomics in optimum glovebox and crewrestraint designs. The activity also contributed to therefinement of methods for quantifying on-orbitobservational data.

ARCHITECTURE AND HABITABILITY

The interior of the International Space Stationsupports activities such as sleeping, eating, personalhygiene, exercising, materials transfer,maintenance, scientific experimentation, stowageand so on. A particularly challenging problem inthe space environment that is relevant to all of thetasks performed on ISS is associated with spatialorientation or knowing how one's body ispositioned relative to the immediate or extendedsurroundings. Without the contribution of the usualground-based vestibular cues, the astronaut isforced to rely exclusively on visual cues. However,this strategy is undermined by the fact that the ISSis designed in accordance with a modularityrequirement. In other words standard hardware"units" such as racks, trays, boxes can be traded andexchanged for other locations on ISS. This designrequirement was levied on ISS in order to facilitateadaptability of the hardware, extended use overtime, and efficient human operations.Unfortunately, the modularity results in uniformityacross the visual field and thereby reducesmeaningful visual cues. Inadequate spatialorientation can result in human user errors as benignas irritation associated with accidentally navigatingdown the incorrect pathway only to have to doubleback. However, this same error can be lifethreatening if it occurs during an emergencyevacuation from ISS. The countermeasures forthese challenges of "neuro-vestibular dysfunction"include the provision of global orientation cues inthe ISS modules and passageways to provide acontinuous awareness of relative and absoluteorientation, as well as more specific informationindicating distinct emergency escape routes, andfinally to training and drills to ensure thatnavigation during emergencies is well practiced.The global orientation cues are simple and intuitive— parts of the structure are always white for the`ceiling' or `overhead' position and the

corresponding parts are colored for the `floor'position. The floor colors are used to code thespecific module.

Since a Shuttle and a Soyuz space craft mayboth be docked to ISS at the same time, and specificcrew members are assigned to each vehicle foremergency evacuations, it is important to be able tolocate the proper emergency exit. Coding signs toshow the way to the exits in three dimensionspresented a challenge.

MODELING

A major challenge for Extra Vehicular Activity(EVA) is the 90 minute night and day cycle. Thevisual difficulties include visual adaptation andappropriate supplemental lighting. There are alsodifficulties due to glare, either direct or reflected,shadowing, and the transitional periods between dayand night. The human factors modeling group haveconstructed precise models of the temporal changesin the visual environment thus enabling the detailedplanning of activities. When there is deviation froma planned activity , real time modeling can be usedto predict exactly what the visual circumstances anddifficulties will be and whether or not a task can becompleted satisfactorily. Robotic operations arealso sensitive to the visual aspects of anenvironment particularly when indirect viewingwith cameras is critical. The modeling is used bymission planners to determine the effectiveness ofavailable lights and cameras to see targets andalignment guides.

Human modeling is also applied during designactivity to supplement or replace the costly and lessversatile use of crew members in analog devices.Such methods have been used in the evaluation ofdesigns for physical and visual access. A recentlyconvened "Interior Volume Control" function istasked with the maintenance of adequate operationaland emergence access as the various pay loads areinstalled in the ISS. An associated problem comeswith the temporary stowage of equipment, material,tools and trash is the space constrained dynamicenvironment. Again modeling of the interiorenvironment, with precise human models facilitatesimportant design, location and operationaldecisions. These same human modeling techniques

have been applied to EVA activities, both formission planning as well as for training. A humanmodel can save time and money when appropriatelyused as a substitute for a real human. (Maida 2001;1999)

INTERNATIONAL PARTNERS

The decision to pursue internationalcollaboration in the design and operation of the ISSbrings additional challenges to crew members,mission operations, designers and the human factorscommunity. Because of the lack of availability of anemergency return vehicle the operational staff of theStation is limited to 3 crew members, who can usethe Soyuz if needed. The makeup of crews duringthe current construction phase requires delicateattention to selection, training, management andpolitical sensitivities. The international partnersinclude the USA, Russia, Japan, Brazil and theEuropean Space Agency. Each of these partnerscontributes to the design and construction of thestation modules and expects a balanced assignmentof crew members. International management stylesdiffer, there are language difficulties, there are evendifferences in the engineering units needed fordesign. Representatives of the NASA space humanfactors community regularly interact withcounterparts in other countries to resolve design andoperations challenges. Some of the challengesinclude the selection of exercise equipment, food,tables, communications arrangements and personalliving quarters as well as the delegation of routineand contingency duties.

Particular challenges that have many earthbound equivalents are those of crew memberproductivity, operation quality, health and safety.The activities on the station include, in approximateorder of priority, sleep, food, exercise, medicalmonitoring, personal time, construction,maintenance, scientific experimentation and publicaffairs, including the role of tour guide. Naturallythe scientific community desires efficiency in theconduct of their experiments that are thefundamental purpose of the venture. However, likeall the best made plans things don't always goaccording to plan and the highly motivated crewmembers sacrifice personal time to "get the jobdone." As mission duration increases to 6 months or

a year, the cumulative effects of microgravity,confinement, isolation and contingency activitieswill take their toll on crew members. Thus activityscheduling and close monitoring of themultinational crew behavior and performancebecomes an operational necessity and a goldmine ofhuman factors knowledge that will be critical in theplanning of long duration exploration missions.

REFERENCES

Gonzalez, L. J., Maida, J., Rajulu, S., (2001) "PredictingStrength and Fatigue For Suited and Unsuited ConditionsFrom Empirical Data", Bioastronautics Investigators'Workshop, January 17-19, 2001, Galveston, Texas, pp. 22-23.

Maida, J.C., L. Javier Gonzalez, S.L. Rajulu, and E. Miles(2001), Predicting Fatigue for Isolated Joints Wearing anExtra-Vehicular Mobility Unit (EMU)., SAE DigitalHuman Modeling for Design Engineering Conference,Arlington, VA.

Maida, J., Novak, J., Mueller, K., (1999). "Effects of TrainingUsing Illumination In Virtual Environments", HumanComputer Interaction, HCI 1999 Proceedings.

Maida, J., (1999) "An Illumination Modeling System forHuman Factors Analyses", Electronic Proceedings of the1999 International Conference on Computer-AidedErgonomics and Safety, Barcelona, Spain, May 19-21,1999.

Morgan, D., Wilmington, R., Pandya, A., Maida, J. andDemel, K., (1996) "Comparison of ExtravehicularMobility Unit (EMU) Suited and Unsuited Isolated JointStrength Measurements", NASA Technical Paper 3613,June 1996.

Novak, J. B., Balmer, D., Morphew, E., Smart, K. (2001)"Operational Habitability For Long Duration SpaceFlight". Presented at the Aerospace Medical Association72nd Annual Scientific Meeting, Reno, Nevada, May 2001

Novak, J.B. (2000) Human Engineering and Habitability: TheCritical Challenges for the International Space Station.Aviation, Space and Environmental Medicine. V.71(9),Section II, p.A 1 17-Al21.

Novak, J.B. (2000) Summary of Current Issues regardingSpace Flight Habitability. Aviation, Space andEnvironmental Medicine. V.71(9), Section 11, p.A 131-A 132..

Novak, J. B., Liddell, G. & Sampaio, C. (1997). HumanEngineering Applied to International Space Station

Design. 27th International Conference on EnvironmentalSystems,tems, Lake Tahoe, Nevada. {SAE Technical PaperSeries No. 972400)

Rajulu, S.L., Klute, G.K., and Fletcher, L. (1994), "Evaluationof COSTAR Mass Handling Characteristics in a Friction-less Environment - A Simulation of the Hubble SpaceTelescope Repair Mission," NASA Technical Paper 3489,NASA-JSC

Rajulu, S.L, Poliner, J., and Klute, G.K. (1993), "LoadsProduced by a Suited Subject Performing Tool TasksWithout the Use of Foot Restraints," NASA TechnicalPaper 3424,. NASA-JSC.

Rajulu, S.L. (1999), "Light-Weight Seat Lever OperationCharacteristics", NASA Technical Paper 209577, NASA-JSC

Rajulu, S.L., and Klute, G.K., (1992), "BiomechanicalAnalysis of Locomotion Patterns in Partial GravityEnvironments," Proceedings of the Human Factors Society36th Annual Meeting, Atlanta, GA.

Smart K., Novak, J. B., Carr, D., Bowen, C. (2001) ISSEmergency Egress - A System for Crewmember PathwayIndication, 31st International Conference onEnvironmental Systems, Orlando, Florida (SAE TechnicalPaper Series No. 2001-01-2184)

Whitmore, M., McKay, T.D. and Mount, F. E. (1995).Ergonomic evaluation of a Spacelab glovebox.International Journal of Industrial Ergonomics, 16, 155-164.