EXTRAVEHIVULAR  MOBILITY  UNIT  SPACE  SUIT:  CRITICAL  HUMAN  FACTOR  APPRAISAL  

Introduction  This  essay  analyses   the  anthropometric,  visual,  control,  cognitive  and  environmental  considerations  involved   in   the   use   of   NASA’s   “Extravehicular   Mobility   Unit   Space   suit”.   Key   Human   factor  considerations  associated  with  its  design  are  discussed  and  possible  improvements  are  suggested.    

Chosen  product  The  space  suit  is  the  greatest  asset  and  symbol  of  human  space  exploration.  It  enables  human  beings  to  undertake  missions  and  challenges  in  an  environment  that  is  completely  hostile  and  unfavourable  for   life   to  exist.   It   is  a  miniature  self-­‐sufficient   spacecraft.  The  NASA’s   “Extravehicular  Mobility  Unit  Space  suit”  was  designed  to  be  the  primary  life  support  system  in  the  hostile  environment  of  Earth’s  Orbital.   It   provides   pure   oxygen   at   pressures   upto   4.3   psi(30   kPa)   while   removing   excess   carbon  dioxide  and    waste  heat  from  the  suit.  A  life  support  system  essential  in  the  suit  lasts  for  upto  8  hours  and   it   weighs   around   178   kg.   Each   space   suit   costs   around   $15-­‐40   million   because   of   its   high  development  costs.  

 

FIG  1.1:  SCHEMATIC  DIAGRAM  OF  A  SPACE  SUIT  

Anthropometric  Considerations  Anthropometry  is  the  measurement  of  dimensions  and  certain  other  physical  characters  of  the  body,  such  as  volumes,  centre  of  gravity,  inertial  properties  and  masses  of  body  segments  etc.    

A  wide  range  of  ethnic  and  racial  backgrounds  were  considered  for  both  male  and  female;.  NASA  for  its   design   considered   the   average   size   of   Japanese   female   as   the   lower   constraint   and   American  (White  or  African)  male  as  upper  constraint  .  A  three  point  average  was  taken  around  5th  Percentile,  50th   Percentile   and   90th   Percentile   of   the   population   to   get   an   accurate   estimation   as   it   ensured  accommodation,  compatibility,  operability  and  maintainability  by  an  astronaut  belonging  to  any  genre.  

Male (American) Female (Japanese) 5th

percentile 50th

percentile 95th

percentile 5th

percentile 50th

percentile 95th

percentile Weight 65.8 kg Height 169.7 cm

82.2 kg 179.9 cm

98.5 kg 190 cm

41.0 kg 148.9 cm

51.5 kg 157 cm

61.7 kg 165 cm

TABLE  BRIEFING  ANTHROPEMTRIC  FINDINGS  

The  measurements  were  considered  in  the  head  plane,  neck  plane,  thorax  plane,  abdominal  plane,  hip  plane,  thigh  flap  plane,  knee  plane,  ankle  plane,  shoulder  plane,  elbow  plane  and  wrist  plane  for  mobility  considerations.  Also,  microgravity  effects  on  the  design  were  considered  because  due  to  weightlessness,  the  human  body’s  height  increases  while  the  body  assumes  a  neutral  body  posture  and  the  body  circumference  changes  with  mass  loss.    Compatibility  due  to  cost  issues  played  a  significant  role  in  design  process  and  hence  the  suit  was  constructed  dimensionally  to  accommodate  such  groups  with  a  design  ceiling  for  reusability  for  each  percentile  cases.

The  dimensional  data  where  catalogued  and  NASA  used  it  to  define  its  work  envelope  for  all  Extra  vehicular  activities  as  in  NASA  Standard  3000  and  NSTS  077000  which  are  shown  below.  This  allowed  NASA  to  understand  the  reach  of  a  potential  astronaut  and  the  kind  of  training  that  would  be  required  to  be  provided  to  them  before  a  mission  so  that  minimum  time  is  spent  on  that  activity  in  space.    

By  undertaking  such  a  study,  NASA  shortlisted  the  individuals  whom  they  could  consider  for  their  potential  Astronauts  Program.    By  ensuring  uniformity  in  body  features;  though  mission  requirements  being  the  chief  selection  factor  for  choosing  an  individual;  the  inter-­‐compatibility  of  space  suits  amongst  astronauts  allows  serious  weight  reduction.  The  most  interesting  aspect  of  the  space  suit  is  that  the  hard  upper  torso  is  uniform  for  all  astronauts  on  a  mission  while  the  arm  as  well  as  leg  lengths  vary  .  It  allows  to  carry  minimum  amount  of  suits  being  required  to  be  taken  on  board  a  mission.  These  extensions  are  attached  to  the  torso  using  connect  rings.  

FIG  1.2:  EVA  WORK  EVELOPE;  NSTS    077000(UNITS  IN  INCHES)  

 

FIG  1.3:  SITTING  WORK  ENVELOPE  IN  HORIZONTAL  PLANE  

Joint  Motion  Design  Considerations  The  primary  role  of  the  EVA  suit  is  to  allow  astronauts  to  undertake  activities  involving  as  much  degrees  of  freedom  possible  in  terms  of  body  movement.  The  weight  of  the  suit,  materials,  life  support  system  as  well  as  space  environment  makes  it  difficult  to  undertake  any  of  such  activity  normally  as  done  in  the  controlled  environment  of  Earth.  The  torque  required  to  bend  an  unoccupied  pressurized  space  suit  by  applying  torque  forces  from  outside  were  compared  to  the  strength/force  applied  by  human  test  subjects  wearing  space  suit.  The  joints  along  the  knee  bend  around  single  axis  whereas  the  shoulder  joint  and  wrist  bends  around  three  axis  to  emulate  free  body  movement  to  the  closest.  It  was  found  that  to  bend  the  knee  at  a  72-­‐degree  angle;  a  torque  of  8.1Nm  was  required  while  to  bend  the  elbow  at  80  degree;  a  torque  of  3.4  Nm  was  required.  These  torque  forces  were  emulated  on  the  suit  in  such  a  way  that  a  normal  human  action  in  a  controlled  gravity  environment  would  produce  a  similar  movement.  Though  the  weight  factor  of  the  suit  acts  variable  for  perceived  motor  actions;  a  number  of  motion  sensors  placed  across  the  key  joints  of  the  body  and  a  continuous  motorized  simulation  of  human  action  similar  to  the  principle  of  bionic  arm  could  make  locomotion  much  easier.  

Visual  considerations  The  ways  in  which  dynamic  information  could  be  displayed  or  communicated  to  an  astronaut  includes:  

 Quantitative  readings    When  the  display  is  a  precise  numeric  value,  which  can  be  ascertained  by  the  user  from  the  data  within  the  suit  and  is  displayed  on  the  mini  screen  on  the  hand  of  the  astronaut  

Voice  over  readings    It  is  used  to  convey  values  or  trends  from  surroundings,  environmental  information  and  work  status  from  the  mission  control  that  depends  on  the  data  relayed  to  it  from  on-­‐board  sensors.    These  are  produced  on  the  alphanumeric  display  located  on  the  DCM  unit  of  the  space  suit.  

Check  readings  These  include  information  related  to  matching,  comparison  and  completion  of  conditions  put  forward  by  mission  control.  These  are  again  translated  to  the  Astronaut  through  voice  over  information  from  Mission  Control  

Important  numbers  like  oxygen  available,  power  available  are  displayed  on    the  DCM  which  is  mounted  on  the  chest.  It  contains  all  the  switches,  gauges,  valves  and  LCD  displays  which  are  required  to  operate  and  control  the  Primary  Life  Support  Subsystem(oxygen  tanks,  CO2  filter,  cooling  water,  radio,  power,  warning  system  etc.).  Since  its  not  in  the  line  of  sight  of  the  astronaut;  a  sleeve  mounted  mirror  is  used  to  control  its  operations.  Such  a  system  enhances  complexity  hence  hand-­‐mounted  button  controls  are  prescribed  though  the  size  of  the  gloves  plays  a  decisive  factor  in  choosing  such  an  option.  

Important   information  relating   to   the   functionality  of   the  spacesuits   is   transferred   to   the  Astronaut  through   the   voice   over   from   Mission   Control.   Once   a   warning   has   been   made,   the   Astronaut  undertakes  necessary  movement/action  to  mitigate  it.  The  amount,  type  and  clarity  of  data  provided  are  key  points  that  need  to  be  taken  into  consideration  hence  a  continuous  track  with  Mission  Control  becomes  a  necessity  as  well  as  failure  mode.  For  example  instead  of  voice  commanding  an  Astronaut  to  decentralise  the  pressure  within  the  suit  or  make  them  known  of  the  available  amount  of  oxygen  left  for  the  mission;  the  on-­‐suit  sensors  should  transfer  the  data  straight  into  the  visor  of  the  astronaut.    Eye   gestures   and   voice   commands   should   be   used   instead   of   switches   and   dials   to   ensure   limited  errors.  

 

FIG  1.4:  DISPLAY  AND  CONTROL  MODULE(DCM)  OF  A  SPACE  SUIT  

 

Control  Considerations  For   all   types   of   systems  with   different   objectives,   the   basic   human   function   in   control   remains   the  same.   Human   receives   information,   processes   it   voluntarily   from   brain   or   involuntarily   from   the  central  nervous  system,  decides  an  option  and  executes  the  action.  The  action  undertaken  by  human,  serves  as  the  control  input  to  the  system.  It  is  necessary  that  the  control  and  display  maintain  some  sort  of  compatibility.    

Spatial  Compatibility  Spatial   compatibility   basically   deals   with   the   physical   similarities   between   the   display   and   their  corresponding  controls.  The  Space  suit  helmet  and  the  display  and  control  module  (DCM)  located  on  the  front  of  the  suit  limits  the  field  of  view  of  a  space-­‐suited  person.  The  field  of  view  as  published  in  NSTS-­‐077000   and   the   work   envelope   available   is   shown   below   which   is   compared   to   a   new  modification   suggested   by   Graziosi,   Stein   and   Kearney   for   further   improvements(GSK).   These  constraints   when   multiplied   with   the   torque   limit   available   to   perform   an   action   limits   the   work  envelope  even  further   into  a  complex  shape  and  increases  the  dependency  of  sensitivity  of   joints  as  the   astronaut   could   face   fatigue   and   prolonged   duration   of   task   requiring   a   tedious   hand   eye   co-­‐ordination.    

 

FIG  1.5:  FIELD  OF  VIEW  AVAILABLE  TO  AN  ASTRONAUT(ALSO  IMPROVED  CONSIDERATIONS)  

Movement  compatibility  Movement   compatibility   becomes   important   in   many   different   circumstances.     The   one   that   is  considered  for  a  space  suit  are  the  movement  of  a  control  device  like  Jetpack  that  produces  a  specific  system  response.  

The  Manned  Manoeuvring   Unit   (MMU)   commonly   known   as   ‘jetpack’   is   a  modular,   self-­‐containing  propulsive  backpack  which  attaches  to  the  space  suit  and  is  donned  &  doffed  by  an  unassisted  non-­‐tethered   Astronaut   in   the   space   suit.   It   increases   the   mobility   of   an   Extra-­‐vehicular   activity   by  allowing  astronauts  to  undertake  activities  further  away  from  the  payload  bay  to  other  portions  of  the  spacecraft,  which  cannot  be  accessed  by  them  tethered.    

Two   independent   identical   propulsion   subsystems   are   used   which   provide   translational   and  rotational  forces  when  necessary.  Each  propulsion  system  consists  of  four  ‘triad-­‐assembly  (three  axis)’  thrusters   that   are   controlled   by   a  motor-­‐driven   isolation   valves.   These   are   controlled   by   the   hand-­‐controller  and  gyro  inputs.  By  manoeuvring  these  rotational  hand  controllers,  it  provides  a  switching  

logic  that  converts  the  motions  of  the  handle  in  three  axis  to  translational  commands.    The  astronauts  use   their   fingertips   to  manipulate   the   controllers  where   the   right-­‐hand   controls   the   rotation  of   the  whole  unit  for  roll,  yaw  and  pitch  while  the  left  controller  takes  it  up,  down,  left  and  right.    In  future  NASA   should   try   to  make   these  gestures   controlled  by  eye  movement  where   they   can   implement   a  same  working  principle  that  of  a  head  mounted  helmet  display  used  by  fighter  pilots.      

 

FIG  1.6:  SCHEMATIC  CONTROLS  OF  A  JETPACK  

Cognitive  considerations  NASA  has  done  an  extensive  research  on  how  humans  process  information  about  their  environment  and   themselves.   It   makes   human-­‐machine   interface   as   an   important   design   process.   Cognitive  engineering,   cognitive   psychology   and   engineering   psychology   are   terms   generally   associated  with  this.    

An  astronaut  training  for  an  Extra  Vehicular  Activity  forms  the  core  of  any  mission.  Astronaut   learn  whilst   they  are  being   trained,   achieve   accurate   level  of  performance   required   to  perform  a   task   for  which   they   are   designated   as   Mission   Specialist.   Research   has   shown   that   while   undertaking   a  repetitive  and  undemanding  task,  a  person  continues  to  learn  and  thereby  refine  their  work  strategies.  They  develop  a  much  more  efficient  way  of  accomplishing  their  task  over  the  time.      

Cognitive  factors  might  play  a  major  role  when  an  Astronaut  gets  acquainted  to  a  particular  control  or  means   to   manipulate   that   control   to   reach   a   desired   result.   In   time   they   would   be   automatically  making   adjustments   and   the   control   action   to  mitigate   a   circumstance  would   become   a   secondary  nature  or  involuntary  process.  

Model   human   processor   is   composed   of   three   systems:   perceptive,   cognitive   and   motor   systems.  Perceptual  and  cognitive  systems  have  memories  associated  with  them.  The  decay  time,  code  and  the  capacity  are  the  three  parameters  that  describe  the  storage  of  information  within  the  brain.  The  code  is  the  form  in  which  the  information  is  stored  in  the  memory.  The  decay  time  is  the  amount  of  time  the  information  would  remain  in  the  memory  with  a  50  percent  chance  of  retrieving  the  information(half-­‐life).  The  capacity  being  self-­‐explanatory  and  is  enormous  for  humans  to  remember  an  action  or  set  of  actions.   The   cognitive  memory   consists   of   a  working  memory   and   a   long   term  memory.   Problems  arise  when  working  memory  and  long  term  memories  contradict  each  other.    

Once   an   Astronaut   is   assigned   to   a   mission,   they   undertake   training   classes   in   a   school.   The   EVA  training   for   the   Astronauts   is   done   at   NASA’s   Neutral   Buoyancy   lab   situated   at   the   Johnson   Space  Center,  Houston,  Texas  as  well  as   for   some  cases   its  undertaken  at   the  Gagarin  Cosmonaut   training  Centre  in  Russia.  A  swimming  pool  tank  is  used  to  simulate  weightlessness,  as  at  neutral  buoyancy,  an  object  doesn’t  floats  or  sinks,  something  similar  to  the  weightlessness  of  a  micro  gravity  environment  of  space.  Astronauts  can  practice  on  how  to  move  heavy  objects  as  a  force  of  gravity  exists  in  a  pull  or  push  motion  between  any  two  objects  given  by  Newton’s  First  and  Third  Law  of  Motion.   It  helps  to  emulate  the  actions  of  slow  movements  on  an  object  and  to  learn  the  effects  of  forces  in  micro  gravity.  This  gives  them  a  technical  and  theoretical  aspect  of  the  mission  where  they  perform  simulations  of  procedures,  which  are  to  be  used  during  the  mission.    

For  every  spacewalk  to  be  performed,  a  several  sets  of  training  units  are  to  be  completed.  EVA’s  can  last  upto  5  hours;  which  is  a  tedious  process  and  has  high  levels  of  stress  and  exhaustion.  Hence  an  Astronaut   needs   to   be   mentally   and   physically   prepared   for   all   possible   circumstances   which  can/could/should   occur   during   their   mission.     Such   training   also   involves   simulating   contingency  scenarios   when   an   activity   could   go   wrong   and   should   be   prepared   to   undertake   all   possible  mitigation  strategies.  Judgement  of  minute  decisions  can  be  question  of  life  and  death  hence  serious  emphasis  is  undertaken  on  the  cognitive  aspects  of  training.  Assignments  to  take  part  in  spacewalks  during  any  mission  depend  on   their  EVA  skills   evaluation,  which   is  undertaken  at  an  early   stage  of  EVA  training  program.  Hereafter  the  shortlisted  candidates  are  provided  with  a  vigorous  EVA  training.    

   

FIG  1.7:  EVA  TRAINING  IN  A  SWIMMING  POOL  AND  THE  ACTUAL  EVA  PERFORMED  ON  HUBBLE  SPACE  TELESCOPE  FOR  THE  SAME  TASK  

 

Environmental  considerations  The  physical  environments  (acceleration,  vibration,  thermal,  etc.),  and  the  human  responses  to  these  environments,  and  the  environmental  design  limits  that  are  based  on  these  human  responses  are  interrelated.  The  Astronaut  is  exposed  to  an  intricate  interplay  of  several  of  these  environmental  factors.  In  this  section  the  environmental  factor  considered  for  are  Illumination,  Heat  &  Cold,  and  Work  Area  Environment:  

Illumination  The   illumination   has   an   impact   on   the   comfort   and   performance   of   the   Astronaut   present   in   any  environment.   The   sensitivity   of   eye   is   not   equal   for   all   wavelengths.   Eyes   are   most   sensitive   to   a  wavelength  of  about  550  nm  at  high  level  of  illumination.    

The  amount  of   light  necessary   for  a   task  depends  on   the   task  performer’s  vision,  nature  of   the   task  and  the  environment  in  which  it  needs  to  be  carried  out.  If  the  brightness  is  significantly  greater  than  that  required;  glare  could  occur.  This  in  case  of  an  Astronaut  occurs  when  they  face  the  sun  directly  or  from  the  Earth’s  albedo  reflection  as  well  as  when  they  are  moving   from  an  eclipse  to  a  day  side  of  Earth  about  the  horizon.  

Glare  causes  discomfort  and  reduces  the  ability  to  see.    It  happens  when  some  part  of  the  field  of  view  is  extremely  bright  when  compared  to  a  general  level  of  brightness.  The  degree  of  glare  depends  on  factors   such   as   brightness,   source   of   light,   position   in   the   person’s   field   of   view   and   the   average  brightness  of  the  surrounding.    Glare  is  defined  as  the  brightness  in  the  field  of  vision  that  is  greater  than  the  luminance  to  which  the  eyes  are  adaptive.  It  causes  annoyance,  discomfort  and  loss  of  visual  performance.  Glares  can  be  either  direct  or  reflected.  Glare  can  be  classified  into:  

• Discomfort  glare    o It  causes  discomfort  to  the  user  but  don’t  normally  affect  visual  performance  

• Disability  glare  o It  reduce  visual  performance  and  visibility  and  are  normally  accompanied  by  discomfort    

• Blinding  Glare  o Intensity  of  this  glare  is  so  high  that  after  an  appreciable  amount  of  time  after  they’ve  

been  removed,  no  object  can  be  seen.    

 

FIG  1.8:  THE  SPACE  SUIT  VISOR  AND  GLARE  CONTROLLERS  

The  amount  of  glare  reduces  as  the  light  source  moves  away  from  the  line  of  sight.  Visual  effectiveness  reduces  from  58%  at  40  degrees  to  16  %  at  5  degrees.  Age  also  influences  the  amount  of  glare.  This  could  be  avoided  by  the  use  of  anti-­‐glare  visors  that  reduce  glare.    The  Space  suit’s  visor  are  plated  

with  metallic   gold   to   filter   sunlight   and   also   provides   thermal   and   impact   protection   from  minute  debris.  It  comes  with  an  adjustable  blinder  to  block  the  direct  sunlight.    

Heat  &  Cold  The   productivity   of   Astronaut   is   strongly   influenced   by   their   comfort   and   health.   The   thermal  environment   is  one  of   the  most  significant   factors  of   those   that  determine  Astronaut’s  comfort.  The  critical   variable   for   survival   is   exposure   time,   which,   for   example,   may   range   from   seconds   for  exposure  to  absolute  vacuum  or  dehydration  which  takes  place  over  the  hours.  The  thermal  effects  on  the   Astronaut   can   be   moderated   by   properly   choosing   the   type   of   clothing.   Differences   between  individuals  in  response  to  thermal  extremes  are  pronounced,  largely  due  to  variations  in  the  length  of  adaptive  period,  called  acclimatization.  Selection  and  training  can  influence  response  to  any  particular  environment  /activity/  clothing  combination.  The  primary  physiological  parameters  related  to  human  thermal   response   are   skin   temperature,   internal   or   core   temperature,   and   weighted   mean   body  temperature.      The   desired   circumstance   is   to   have   the   body   at   a   state   of   equilibrium  with   the   environment   in   a  condition  that   is  comfortable  (typically  defined  as  39*C  body  temperature  and  1  bar  pressure).  The  principal  effect  of  a  microgravity  environment  on  heat  transfer  is  the  loss  of  natural  convection.  The  temperature  fluctuation  varies  from  120*C  in  sunlight  to  -­‐100*C  in  shade.  The  space  suit  provides  air  pressure  to  keep  the  fluids  in  a  liquid  state.  The  space  suit  works  at  an  operational  pressure  of  0.29  atm   space   suits,  which   is   heavily   insulated  with   layers   of   fabric   (Neoprene,   Gore-­‐Tex,   Dacron)   and  covered  with  reflective  outer  layers  (Mylar  or  white  fabric)  to  reflect  sunlight.  To  remove  the  excess  heat  generated  from  the  human  body,  space  suits  have  used  either  fans/heat  exchangers  to  blow  cool  air,  as   in  the  Mercury  and  Gemini  programs,  or  water-­‐cooled  garments,  which  have  been  used  from  the  Apollo  program  to  the  present.  The  suit  itself  has  13  layers  of  material,  including  an  inner  cooling  garment  (two  layers),  pressure  garment  (two  layers),  thermal  micrometeoroid  garment  (eight  layers)  and  outer  cover  (one  layer).  Maximum  Absorption  Garment  (MAG)  collects  the  urine  produced  by  the  astronaut  while   the   Liquid   Cooling   and   Ventilation   Garment  (LCVG)   removes   the   excess   body   heat  produced  by   the  astronaut  during  spacewalks.  NASA   in   its   future  design  should   try   to  decrease   the  number  of  materials  used  especially  Kevlar  and  Nomex  because  of  its  weight  considerations  and  use  carbon  fibres  as  an  alternative  while  having  a  separate  heating  system  for  hands  as  they  get  coldest  while  performing  perspiring  task.    

FIG  1.9:  DIFFERENT  LAYERS  OF  GARMENT  OF  THE  APOLLO  SPACE  SUIT(EMU  GARMENTS  ARE  BASED  ON  SAME  PRINCIPLE)  

Working  Area  Environment  The   microgravity   environment   of   outer   space   is   the   harshest   environment   ever   faced   by   human  beings  that  has  absolutely  no  features  to  sustain  life.  If  exposed  to  the  space  vacuum  a  person  would  become  unconscious  within  15   seconds  because  of  non-­‐availability   of   oxygen.  Hence   the   space   suit  requires   to   maintain   a   pressurized   atmosphere   around   the   human   body   while   providing   regular  supply   of   oxygen   and   removing   carbon   dioxide.   Also,   it   requires   to   maintain   a   stable   working  temperature  despite  tireless  work  and  movement  within  dark  and  light  areas  within  the  orbit.  Also,  protection  from  micrometeoroids  and  radiation  is  a  must  because  of  which  Kevlar  protection  is  used.  As   stated  above,   a  pressure  of  0.29  atm   is  maintained  within   the   suit  while  a   supply  of  100%  pure  Oxygen  air   is  provided  to  astronauts.  To  protect  Astronauts   from  dehydration,  a  supply  of  0.95  L  of  water  in  a  drinking  bag  is  provided  to  maintain  continues  fluid  supply  during  space  walks.    

NASA  in  its  future  missions  should  consider  having  an  inflatable  sail  around  the  Astronaut  to  protect  them   from   serious   debris   impact   and  maintain   an   envelope   of   controlled   environment   away   from  Sun’s  glare.  

Conclusion  

From  the  above  discussion;  it  is  evident  that  the  NASA’s  EMU  Space  suit  is  one  of  the  greatest  feat  of  human   engineering.   It   allowed   humans   to   undertake   physical   activities   in   environments   that   are  completely  hostile   for  any   form  of   life   sustenance  or  human  comfort.  They  have  undertaken  all   the  design  considerations   in  extremely  detailed   fashion,  however   some   improvements  are   still  possible  and  have  been  suggested  such.

Reference  

1.M.S.Sanders,E.J.McCormick  (1993).  Human  factors  in  Engineering  and  Design.  Singapore:  McGraw-­‐Hill.    

2.  .Gavriel  Salvendy  (1997).Handbook  of  human  factors  and  ergonomics(second  edition).John  Wiley  &  Sons:  New  York  

3.  NASA;  NASA-­‐STD-­‐3000  Manual;  Section  3;  Available  at:  http://msis.jsc.nasa.gov/sections/section03.html;  accessed  on  15th  May  2014  

4.  NASA;  Constellation  Spacesuit  briefing;  Available  at:  http://www.nasa.gov/pdf/246726main_ConstellationSpaceSuitSystemBriefing.pdf;  last  accessed  on  15th  May  2014  

5.  Craig  Freudenrich;  How  Spacesuit  works;  Available  at:  http://science.howstuffworks.com/space-­‐suit1.htm  ;  last  accessed  on  15th  May  2014  

6.  NASA;  Space  suits  and  spacewalks;  Available  at:  http://www.nasa.gov/audience/foreducators/spacesuits/facts/facts-­‐index.html  ;  last  accessed  on  15th  May  2014    

7.    Patricia  Barrett  Schmidt;  MIT(2001);  An  Investigation  of  Space  Suit  Mobility  with  Applications  to  EVA  Operations  

8.  M  Huynh;  McDonnell  Douglas  Astronautics  Company  Houston  Division(1988);  Assessment  of  the  manned  maneuvering  unit;  Working  Paper  no.  1.0-­‐WP-­‐VA88003-­‐11  

APPENDIX  

Figure A1: Anthropometric Dimensional Data for American Female Body Size of the 40-Year-Old Japanese Female for Year 2000 in One Gravity Conditions

No. Dimension 5th percentile 50th percentile

95th percentile

805 Stature 148.9 (58.6) 157.0 (61.8) 165.1 (65.0) 973 Wrist height 70.8 (27.9) 76.6 (30.2) 82.4 (32.4) 64 Ankle height 5.2 (2.0) 6.1 (2.4) 7.0 (2.8)

309 Elbow height 92.8 (38.5) 98.4 (38.8) 104.1 (41.0) 169 Bust depth 17.4 (6.8) 20.5 (8.1) 23.6 (9.3) 916 Vertical trunk

circumference 136.9 (53.9) 146.0 (57.5) 155.2 (61.1)

612 Midshoulder height, sitting 459 Hip breadth, sitting 30.4 (12.0) 33.7 (13.3) 37.0 (14.6) 921 Waist back 35.2 (13.9) 38.1 (15.0) 41.0 (16.1) 506 Interscye 32.4 (12.8) 35.7 (14.1) 39.0 (15.4) 639 Neck circumference 34.5 (13.6) 37.1 (14.5) 39.7 (15.6) 754 Shoulder length 11.3 (4.4) 13.1 (5.1) 14.8 (5.8)

 

 

 

 

 

 

 

 

FigureA2: Anthropometric Dimensional Data for American Male Body Size of the 40-Year-Old American Male for Year 2000 in One Gravity Conditions

No. Dimension 5th percentile 50th percentile 95th percentile

805 Stature 169.7 (66.8) 179.9 (70.8) 190 1 (74.8) 973 Wrist height 64 Ankle height 12.0 (4.7) 13.9 (5.5) 15.8 (6.2)

309 Elbow height 236 Bust depth 21.8 (8.6) 25.0 (9.8) 28.2 (11.1) 916 Vertical trunk circumference 158.7 (62.5) 170.7 (67.2) 182.6 (71.9) 612 Midshoulder height, sitting 60.8 (23.9) 65.4 (25.7) 70.0 (27.5) 459 Hip breadth, sitting 34.6 (13.6) 38.4 (15.1) 42.3 (16.6) 921 Waist back 43.7 (17.2) 47.6 (18.8) 51.6 (20.3) 506 Interscye 32.9 (13.0) 39.2 (15.4) 45.4 (17.9) 639 Neck circumference 35.5 (14.0) 38.7 (15.2) 41.9 (16.5) 754 Shoulder length 14.8 (5.8) 16.9 (6.7) 19.0 (7.5) 378 Forearm-forearm breadth 48.8 (19.2) 55.1 (21.7) 61.5 (24.2)

 

 

 

 

 

 

 

 

 

 

FigureA3: Torque Vs. Angle for EMU shoulder, elbow and knee; further improvement as prescribed by Dionne, Menendez, Abramov and Morgan