1.32 Extravehicular Activity (EVA) Operations Overview

1.32 Extravehicular Activity (EVA)
Operations Overview
As a result of the Extravehicular Activity (EVA) Operations Overview presentation,
students should be prepared to do the following:
•  Identify the reasons for conducting an EVA and the role that EVA plays in the space
•  Identify the types of EVAs that are trained and may be performed on orbit.
•  Identify the roles of the Extravehicular Mobility Unit (EMU), Simplified Aid For EVA
Rescue (SAFER), Shuttle Airlock, and ISS Joint Airlock.
•  Identify the roles that different Space Shuttle and Space Station equipment and tools
play during an EVA.
•  Identify the methods and procedures of EVA Prep, EVA, and Post EVA operations for
Shuttle and Station.
•  Define the role MOD plays in the EVA program.
•  Define the roles that different training facilities play in EVA training.
NOTE: MOD EVA also has some responsibilities for Russian-based Orlan EVAs. However, this
material is beyond the scope of this briefing.
•  EVA Categories
•  EVA Systems
•  EVA Equipment and Tools
•  EVA Operations Overview
•  MOD’s EVA Role
•  EVA Training Facilities
•  Web Links
EVA Categories
Extravehicular Activity (EVA)
•  Definition: Crewmember leaves the protective environment of a pressurized
spacecraft cabin and ventures out into vacuum of space wearing an EMU
• Purpose
- Contingency Repairs
- Mission Success Repairs
- Experiments or Testing
- Spacecraft Servicing (Hubble Space
- Space Structure Construction [International
Space Station (ISS)]
EVA Categories
ISS vs Shuttle Terminology
Three basic categories of EVA exist:
1.  Nominal* or Scheduled EVA:
EVA planned prior to launch and
included in the nominal mission
2.  Off-Nominal* or Unscheduled EVA:
EVA not included in the nominal
scheduled mission activities but
which may be required to achieve
mission or operational success.
3.  Contingency EVA:
EVA required to effect the safety of
the crew and vehicle (Orbiter or ISS)
(we have performed 0 contingency
*Terminology for ISS based EVAs
EVA Systems
•  Extravehicular Mobility Unit (EMU)
•  Simplified Aid For EVA Rescue (SAFER)
•  Shuttle Airlock
•  ISS Joint Airlock
EVA Systems
The EMU is an independent system that
provides the crewmember with
environmental protection, mobility, life
support, and communications during
EMU provides consumables to support an
EVA of 7 hours maximum duration.
Primary Life
Support System
•  15 minutes for egress
•  6 hours for useful work
•  15 minutes for ingress
•  30 minutes for reserve
EMU is an integrated system consisting of
two subassemblies:
•  Life Support System (LSS)
•  Space Suit Assembly (SSA)
EVA Systems
Two EMUs* are baselined to be flown on each shuttle flight with enough consumables
to support 3 two-crewmember (Orbiter contingency) EVAs.
Of these 3 EVAs:
•  One 7-hour EVA may be supported.
•  Two EVAs of 3-hours and 4-hours respectively may be supported for contingency
EVA operations.
* A third EMU is sometimes flown as a spare on flights with a scheduled EVA or to
preserve redundancy on ISS assembly flights.
* Three or four EMUs can be flown on flights requiring two EVA teams.
EVA Systems
Life Support System Components:
•  Primary Life Support Subsystem
-  Provides breathing O2, electrical
power, comm, cooling
-  Responsible for suit pressure control
-  Circulates O2 and removes CO2,
humidity and trace contaminants
-  Controls thermal environment
•  Secondary Oxygen Pack (SOP)
-  Provides a minimum of 30 minutes
of emergency O2 in open loop purge
-  Activated automatically during
EVA, if necessary
•  Contaminant Control Cartridge (CCC;
LiOH Cartridge or METOX Cartridge)
-  Removes CO2 and trace
EVA Systems
Life Support System Components
•  Battery
•  Space to space EMU Radio (SSER;
EMU Radio)
•  Caution and Warning System (CWS)
•  Display and Control Module (DCM)
-  Provides CWS messages, EMU
parameters, and EMU controls to
•  Real Time Data System (RTDS)
-  Provides EMU status parameters and
biomed data for transmission to
Mission Control
EVA Systems
Space Suit Assembly Components:
•  Hard Upper Torso (HUT)/arms
•  Lower Torso Assembly (LTA)
•  Extravehicular (EV) gloves
•  Helmet/Extravehicular Visor
Assembly (EVVA)
•  Liquid Cooling and Ventilation
Garment (LCVG)
•  Operational Bioinstrumentation
System (Biomed)
•  Communications Carrier Assembly
(CCA; Comm Cap)
•  Disposable In-Suit Drink Bag (DIDB)
•  Maximum Absorption Garment
EVA Systems
SAFER (Simplified Aid for EVA Rescue)
SAFER is a self-contained, propulsive backpack self-rescue system that provides the EV
crewmember with self-rescue capability when orbiter is not present or cannot
immediately perform EVA rescue.
• Propellant: Pressurized nitrogen gas
• Controlled by a single hand controller
• Stowed in ISS airlock, used on ISS
• Sufficient propellant and power for one
self-rescue (~13 min)
• Test flight on mission STS-64; self
-rescue capability on STS-76
• Power up of production model SAFER
on STS-86
• Tethered test flight of production
model SAFER on 2A and 3A
EVA Systems
SAFER (Simplified Aid for EVA Rescue)
EVA Systems
Shuttle Airlock
The shuttle airlock provides the following:
•  The means for a suited EVA crewmember to transfer
from the orbiter to the EVA environment without
having to depressurize the crew cabin.
•  EMU life support during prep/post EVA operations:
-  O2
-  Power
-  Cooling
•  Recharge of EMU consumables:
-  O2
-  Battery
-  Feedwater
•  Ability to move between Space Hab or Spacelab with
the attachment of the tunnel adaptor
EVA Systems
ISS Joint Airlock
ISS Joint Airlock:
•  Primary for US ISS EVAs (both Orbiter
and Station based)
•  Compatible for use with Russian Orlans
•  Made up of two parts: Crew Lock and
Equipment Lock
– Equipment Lock is used for
stowage, recharge and servicing of
EMUs, and to don/doff the EMUs
– Crew Lock is the volume nominally
depressed to vacuum for crew to go
Equipment Lock
Crew Lock
U.S. Lab
EVA Equipment & Tools
EVA crewmembers use specific tools for each task
and this generic equipment:
•  Tethers
-  55' safety tether, 2 waist tethers, wrist tethers
-  EVA tether protocol is that crewmembers and
equipment must be tethered at all times
-  Always make a connection before you
break a connection.
•  Mini Workstation (MWS)
-  Attaches to front of the EMU
-  Used to carry small tools
-  MWS end effector and retractable tether
provide restraint to EV CM at worksite
• Body Restraint Tether (BRT)
-  Attaches to the MWS
-  BRT end effector provides semi-rigid restraint
to EV CM at worksite
-  Requires less time than setting up a Portable
Foot Restraint and is more stable than a MWS
end effector
-  Also used for translating small objects
EVA Equipment & Tools
•  Pistol Grip Tool (PGT)
– EVA torque wrench (i.e. a bolt turner)
– Has a programmable torque limiter and
turn limiter
– CM needs to be secured depending on
amount of torque required
– 2ft-lbs to 25ft-lbs of torque available
– Generally used for ISS assembly
missions and maintenance EVAs
 1-G Testing of the PGT
EVA Equipment & Tools
Foot Restraints
-  Attaches to structure via a socket
-  Provides EV CM rigid restraint at a
-  Different types:
-  Portable foot restraint (PFR) (Shuttle)
-  Articulating PFR (APFR) (US ISS)
-  Interoperable APFR (IAPFR) (US &
Russian ISS)
Tool Stanchion (no picture)
–  Attaches to APFR or CETA Cart
–  Levers allow CM to yaw and tilt with
respect to APFR
–  Holds tools and provides temp
stowage of old ORUs
EVA Equipment & Tools
• Crew and Equipment Translation Aid
(CETA) Cart
–  Essentially an EVA equipment cart
–  Translates by CM manually pulling
it along truss
–  Use brakes to stop and stay parked
–  Typical use: small ORU
replacement on front truss face
• Crane
– Used to transfer ORUs during maintenance EVAs
– Pitch and yaw capabilities
– Telescoping boom (18 feet)
– Smaller than Russian crane (STRELA)
EVA Operations Overview
EVA operations can be divided into three phases.
Operations to prepare for EVA
EVA Tasks
Operations after EVA
EVA Operations Overview
Operations to prepare for EVA
•  Equipment Prep
–  Prepares the airlock and the EMUs to be checked out before EVA. This is
normally performed a few days before the EVA or before the Orbiter docks to
the Station.
•  EMU Checkout
–  Checks all EMU systems. Performed a few days before the EVA or before the
Orbiter docks to the Station.
•  EVA Prep
–  All steps performed the day of the EVA prior to going EVA, including:
–  EMU Donning
–  Prebreathe with 100% oxygen
EVA Operations Overview
Operations to prepare for EVA
O2 Prebreathe reduces the risk of Decompression Sickness (DCS)
Mask prebreathe time
In-suit prebreathe time 4 hours
Ops Overview
(Details of EVA Prebreathe
protocols are in the
Aeromed Flight Rule
Breathe O2
in-suit for 4
hours while
cabin is at
14.7, go out
the door.
10.2 (12
10.2 (24 hr)
1 hour
1 hour
80 minutes
75 minutes
40 minutes
1 hour
Breathe O2
on mask
cabin to
10.2, wait
12 hours
before insuit
go out the
Breathe O2 on
mask while
cabin to 10.2,
wait 24 hours
before in-suit
prebreathe, go
out the door.
Exercise on bike
for 10 min. at
beginning of mask
depress airlock to
10.2, breathe insuit for 1 hour, go
out the door.
EVA Operations Overview
EVA Tasks
30 min
Airlock depress
15 min
Airlock egress
Worksite operations: Shuttle and ISS-based
–  All Shuttle EV crewmembers are trained to perform the
following Orbiter contingency tasks (if necessary) for each
•  Failed airlock hatch latches or actuator tasks
6 hours
•  Failed Remote Manipulator System (RMS) tasks
•  Manual stowage of radiators or Ku-band antenna
•  Manual closure of payload bay doors
•  Installation of payload bay door latch tools
•  Manual separation of Shuttle from ISS (96 bolt task)
–  EVA crewmembers assigned to a flight are also trained for
scheduled, unscheduled, or contingency tasks.
15 min
Airlock ingress
30 min
Airlock repress
EVA Operations
Operations after EVA
EMU Doffing
EMU Maintenance and Recharge
–  O2 Tank recharge
–  Battery recharge
–  H2O tank refill
–  METOX regeneration/ LiOH swap
–  Suit cleaning
–  Suit resize (if required)
Post EVA Entry Prep
MOD’s EVA Role
Three EVA Organizational groups at Johnson Space Center
EVA Office (XA)
Long-range flight planning
Purchasing of flight hardware
General oversight
Engineering (EC5)
Development and testing of EVA hardware
MOD (DX32, DX35)
Operations development
Crew training
Flight control
EVA Training Facilities
•  Shuttle Full-size Mockup Trainers
-  Crew Cabin Trainer (CCT) and CCTII
-  Full Fuselage Trainer (FFT)
•  Precision Air-Bearing Floor (PABF)
•  EVA Comm Trainer
•  Space Station Mockup Training Facility (SSMTF)
Airlock Mockup
•  Virtual Reality Lab
•  Vacuum chambers
-  11 foot chamber
-  Environmental Test Article (ETA) chamber
-  Space Environment Simulation Lab (SESL)
-  Space Station Airlock Test Article (SSATA)
•  EMU Caution and Warning System (ECWS) Trainer
•  Neutral Buoyancy Laboratory (NBL)
•  KC-135
WEB Links
DX32/35 Home page –
EVA History/Advanced suit program –
Hamilton Sunstrand(designers of the EMU) Applications/SpaceSuits/
EC5 Homepage –