The Space Shuttle Extravehicular
Mobility Unit (EMU)
The world’s smallest spacecraft, or,
the ultimate in Personal Protective
Equipment to operate in perhaps the
most dangerous environmental
where man has ever gone.
Mercury Space Suit
1958-1963
• 1 astronaut in the capsule
• Used in high altitude fighters
• The suit had 2 layers, inner
gas bladder layer and outer
restraint layer
• The suit restricted easy
movement
• Discomfort due to poor
temperature control and
inability to turn the head
within the pressurized suit
Project Gemini
Space Suit 19641966
• Based on X 15 flight suit
• 6 layers of nylon, Nomex layer
and link net retaining layer
• Gloves detachable with locking
rings that allowed rotation of
the wrist.
• Later versions added additional
layers of Mylar insulation for
temperature control
• Improved mobility in shoulders
and arms and was more
comfortable when worn
unpressurized during space
flights lasting up to 14 days.
Project Gemini
Space Walk 1965
• First USA EVA, astronaut left the
vehicle June 3, 1965
• Connected to the capsule by an
oxygen feed hose that served as
a tether line with
communication.
• No actual walking was involved
• Use of small hand held gun
propulsion gun
• Astronauts had logged nearly 12
hours of space experience
• Proved that useful work could be
done outside of the a spacecraft
w/o life threatening exhaustion.
Apollo Space Suit 1963-1972
• Actual lunar spacewalks
on the moon were
being planned.
• Serve as backup to
pressure system
• Had to allow flexibility
in the shoulder, arm,
legs and waist
• Astronauts were
expected to bend and
pick up samples
Apollo Space Suit
• Had to function both in
microgravity and in the
one-sixth gravity of the
Moon’s surface
• A self contained
portable life support
system would be
needed, astronauts no
longer tethered to craft
life support system
Apollo Space Suit
• Water cooling garment
• Multi layered pressure
garment to contain the
pressure in the suit
• Bellow like rubber joints
at the waist, elbows,
shoulders, wrist, knees
and ankles
• Provide protection
against micro
meteoroids and wear
and tear of walking on
the moon
Apollo Space Suit For EVA
• The suit had 14 layers made
up of
– 5 layers of aluminized Mylar,
4 layers of Dacron
– 2 layers of an aluminized film
and outer layer
– 2 layers of thermal protection
– 1 outer layer to provide
flame/fire protection.
Outermost was white Teflon
material
Comments re Apollo Suit
• “The little EMU, the
combination of
spacesuit and backpack
that sustained our life
on the surface
operated magnificently
…….. Far too little
time….we were like a
five year old boy in a
candy store.”
Apollo EVA Space Suit
• Clear polycarbonate plastic pressure helmet with
communications headset and sun filtering visors
and blinders
• Suit also included protective boots, a portable life
support system (PLSS) and custom sized gloves
with molded silicone rubber finger tips
• The life support system was a backpack unit,
provided oxygen for breathing and pressurization,
water for cooling and radio communication for
lunar excursions lasting up to 8 hours
• During the Apollo program, 12 astronauts spent a
total of 161 hours of EVA on the Moon
Apollo Specifications
Missions: Apollo 7-14 / 15-17
Function: Intra-vehicular activity (IVA), orbital Extra
Vehicular Activity (EVA) and terrestrial Extra-vehicular
activity
•
Operating pressure: 3.7 psi
•
IVA Suit weight: 62 lbs.. / 64.6 lbs..
•
EVA Suit weight: 76 lbs.. / 78 lbs..
•
Total EVA Suit weight: 200lbs / 212 lbs..
•
Primary Life Support: 6 hours / 7 hours
•
Backup Life Support: 30 minutes / 30 minutes
•
Custom built for each astronaut, 3 suits for each
astronaut
Lunar Rover
• Changes were made to the
Apollo EVA suit to allow the
astronauts to operate the
Lunar Rover
• Two new joints at neck an
leg.
• A waist joint was added
• EVA backpacks were
modified to carry more
oxygen, LiOH, more power
and more cooling water.
Skylab 1973-1974
• NASA’s first space station
• Launched 6 months after the last Apollo Moon
landing
• Shield ripped away soon launch that deployed
2 of the 6 solar panels.
• Panels were freed after an EVA
• Additional EVA for repairs
• Skylab astronauts logged 17.5 hours of
planned EVA and 65 hours of unplanned EVA
Skylab Space Suit
• Modified Apollo suits
• Lunar EVA backpack
was replaced with
Gemini style umbilical.
• Breathing air for and
liquid water for cooling
• Emergency oxygen
bottle attached on leg
Skylab Suit Specifications
• Function: Intra-vehicular activity and orbital
Extra vehicular activity
• Operating pressure: 3.7 psi
• IVA Suit Weight:
64.6 lbs..
• EVA Suit Weight: 72 lbs..
• Primary Life Support: Vehicle provided
• Backup Life Support:
30 minutes
Space Shuttle Program 1981 - 2004
• EMU designed to be used with
the Space Shuttle for building
the International Space
Station, launching and repair
satellites and other items.
• Modular system that allows
interchangeability of
component and address sizing
requirements.
• Very different than Apollo
Suit, have hard upper torso
and integrated PLSS.
EMU in Use
• The Baseline EMU went into
use on 4/12/81, through
2002
• The first EVA was 4/6/83
• From 1983 to 2002, EMU
supported 58 EVAs for a total
of 619.5 man-hours.
• Crewmembers went EVA for
7, 8 or more hours every
other day w/o ill effects
• Enhanced EMU went into
service in 1998.
• From 2002 to present only
enhanced suits in use
Space Shuttle EMU
• Can fit 5th to 95th percentile male and female
astronauts
• First a training suit is created and then a
mission suit is created
• Upon completion of the mission, space suit is
disassembled
• Modular System, 18 different items
• 7 in the Life Support System
• 11 Space Suit Assembly
Enhanced EMU
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SAFER Capability
Pivoted Hard Upper Torso
Orbital Replacement Unit
Enhancements to the EMU”s pressure
garments
• Heated gloves
• Changes to the CCC
EMU Specification
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Mission Duration 7 hours EVA
Operating Environment 0 Pisa to 14.7 Pisa
Suit Operating Pressure 4.3 psid (differential
Emergency Life Support 30 minutes
Useful life
Up to 30 years
Weight 275 pounds
Donning 15-30 minutes
Space Suit Assembly
• The suit is made up of
o 2 layer cooling and ventilation
o Urethane coated nylon pressure bladder 2 layers)
o Aluminized Mylar/thermal meteoroid garment (7
layers)
o Outer layers (2 layers)
• Other parts of the Space suit assembly
o Fiberglass hard upper torso
o Ball bearing joints (Arm, wrist, leg)
o Polycarbonate helmet and visors
o On orbit resizing
What Makes up the EMU
• Liquid and Cooling Ventilation Garment
(LCVG)
• Service and Cooling Umbilical (SCU)
• EMU Electrical Harness (EEH)
• Display and Control Module (DCM)
• Extravehicular Visor Assembly (EVA)
• Helmet
• Arm Assembly
• Gloves
Make Up of EMU
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Lower Torso Assembly (LTA)
Hard Upper Torso Assembly (HUT)
Primary Life Support Subsystem (PLSS)
Secondary Oxygen Pack (SOP)
Contaminant Control Cartridge (CCC)
Battery
Airlock Adapter Plate
Communications Carrier Assembly CCA)
In Suit Drink Bag (IDB)
Primary Life
Support System
(PLSS)
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Oxygen supply
Suit pressurization
Communications
Breathing gas purification
Temperature Control, water
cooling equipment
• Independent emergency
life support
• Orbital Replacement Unit
capability
EMU Helmet Assembly
• Transparent shell, Neck
Ring, Vent Pad, Purge
Valve and an adjustable
Valsalva Device
• Vent assembly diffuses
the incoming gas over
the astronauts face
• Have several visor filters
• Astronauts wears the
communications carrier
assembly, Snoopy Hat
EMU Front View
EMU Display and Control Module
Donning the EMU
• Suit can be put on in 15 - 30
minutes
• When working in the
Shuttle Cabin, crew
members breathe a mix of
nitrogen and oxygen at 101
kilopascals
• The Suit’s atmosphere is
pure oxygen at 28.6
kilopascals
• Prebreathing is done at 70.3
pascasl while percentage of
oxygen kilopascals is
increased
Donning the EMU
• Crew doing EVA dons a mask connected to the
oxygen supply in the shuttle
• The length of time w/o cabin depression and
prebreathing is related.
• A prebreathe of 30 minutes is safe providing
decompression takes place at 24 hours before
• Later after the astronauts don the entire suit,
and seal the helmets, an additional
prebreathe of 30-40 minutes
Donning the EMU
1. Put on the Maximum
Absorbency Garment
Enter the airlock
2. Put on the LCVG
3. Attach the EMU
Electrical Harness to the
HUT (EEH)
4. Attach the Display
Control Module (DCM)
to the HUT
5. Attach the arms to the
HUT
6. Rub the helmet with
anti-fog
Donning
7. Place the wrist mirror and checklist on the
sleeves
8. Insert a food bar and water filled IDB inside of
the hut
9. Check the lights and TV camera
10. Place the visor over the helmet
11. Connect the Communications Carrier
Assembly to the EEH
12. Step into the Lower Torso Assembly and pull it
above the waist
Donning
13. Place the Service and Cooling Umbilical into the
DCM
14. Squirm into the upper torso portion of the suit
with the arms attached
15. Attach the cooling tubes of LVCG to the PLSS
16.Attach the EEH electrical components to the
PLSS
17. Lock the Lower Torso Assembly to the HUT
18. Put on the CCA and eyeglasses
Donning – Almost Ready
19. Put on comfort inner gloves
20. Lock on the helmet and EVA
21. Lock on the outer gloves
22. Check the EMU for leaks
READY
• EMU automatically depressurizes to operating
pressure
Ready For EVA
• No leaks mean the airlock is depressurized
• The EMU automatically depressurizes to its
operating pressure
• The suit is tethered to the air lock
• The outer air lock door is opened
• The SCU is disconnected from the EMU
• The astronaut steps out of the airlock into the
shuttle cargo bay
US versus Russian
• The suits and their self contained life support
systems appear similar from the outside
• Not compatible
• Each suit has its own strength and weaknesses
• US Suit is more difficult to put on, operates at a
lower pressure, offers greater freedom of
movement
• Russian suit easier to put on, and adjusts to
different sizers easier however it is sized for a
smaller range of body sizes
Comparison
• US Suit is modular but need to inventory sizes of
the various components
• Russia space suit has a higher operating pressure,
that makes it easier to do certain tasks and
reduces the time for pre-breathing Russian EVAs
are different and are typically shorter
• Russian tethers are easier to use
• Space Station has both, astronauts are trained on
both
EMU with MMU
Manned Maneuvering Unit
• Propulsion backpack used on 3 space shuttle
missions in 1984
• Fit over the PLSS
• Allowed astronauts to perform untethered EVA
spacewalks at a distance from the shuttle
• Gaseous nitrogen was the propellant
• Use stopped after Challenger accident
• SAFER provides capability to return to Space
Station
An EMU with MMU in Use Distant Shot
An EVA to launch a communications satellite
Changes Shuttle Priorities
• After the loss of the Challenger, most routine
satellite launches even for NASA missions had
returned to unmanned rockets.
• After the loss of the Columbia the President
decided that the shuttle program would be
retired as soon as construction of the ISS was
completed.
• It was the end of an era for manned
spaceflight
Making Upgrades to Hubble Telescope
Personal Protective Equipment
• Where hazards can not be minimized or eliminated
by engineering means.
• PPE for eyes, face, head and extremities, protective
clothing shall be provided and maintained in a
sanitary and reliable condition .
• The use requires a detailed assessment and
training
• Assess the hazards to the eyes and face
– Flying particles
– Injurious light radiation
PPE Cont’d
• Respiratory Protection
– Breathing contaminated air
– IDLH environments
– Supplied air system
– Medical approval and surveillance
• Head Protection
– Possible danger of head injuries
– Impact or flying or falling objects
PPE Cont’d
• Foot Protection
– Possible foot injury due to falling or rolling objects
• Fall Protection
– Falls from an elevation
• Hand and Skin Protection
– Severe cuts or lacerations, severe abrasions,
thermal burns and harmful temperature extremes
Some Interesting Facts
• The suits cost 12 million dollars each, revised now
to 20 million
• There were 16 PLSSs made up originally
– 2 suits were lost on the Challenger
– 2 suits were lost on the Columbia
– There may be have been 2 recent suits lost in a Soyuz
mishap.
• On ISIS, there are 2 complete US suits, 2 Russian
Orlan suits and 1 Short EMU, generic
• The suits can be recharged from the Space
Station
Who have worn the Suits
• Of the 312 Astronauts since 1959, at least 207
have been Scouts or active in Scouting.
– 39 Eagle Scouts, 25 Life Scouts, 14 Star Scouts, 26 1st
Class Scouts, 17 were 2nd Class, 13 Tenderfeet and 73
other ranks or positions including 27 Girl Scouts
– 3 astronauts on the Apollo 1, 4 of the 7 on the
Challenger and 5 of the 7 on the Columbia were
Scouts
– The 27 Girl Scout alumni flew at least 40 of the 114
Space Shuttle missions