AIAA-SpaceSuit-Water-Intrusion_05062016_final

Finding Solutions to NASA’s Spacesuit
Water Intrusions during EVA
Keisha Antoine, PhD, PE
Antoine Technical Consulting LLC, Houston, TX
Yvonne Vigue-Rodi
Adelante Sciences Corporation, Houston, TX
AIAA Annual Technical Symposium
May 6, 2016

May 6, 2016 AIAA Houston Annual Technical Symposium
Introduction & Problem Statement
• NASA ISS crew members have been experiencing in-flight anomalies during EVAs
for the past 3 years.
• Water intrusions within the helmet on separate EVAs have caused spacewalks to
be terminated early for the safety of the crew members.
• NASA leadership and ground support engineers and technicians are working
diligently to prevent future recurrences.
• Excess water in ventilation loop came from thermal loop because of
fan/pump/separator malfunction

Astronaut Date EVA # EMU #
Luca Parmitano July 9, 2013 22 3011
Luca Parmitano July 16, 2013 23 3011
Terry Virts February 25, 2015 30 3005
Tim Kopra January 15, 2016 35 3011
Water Intrusion Incidences During Recent
EVAs on ISS
Corrective Actions
• Helmet Absorption Pad (HAP)
• Major overhaul with refurbished components including fan/pump/separator
• New EMU servicing procedures – regular water sampling, more frequent water
loop scrubs, filter replacements

Based on our study of the problem
Our Objectives
1. Understand source of the water found in the helmet
2. Identify source of silica in phase separator
3. Propose recommendations

May 6, 2016 AIAA Houston Annual Technical Symposium 5
Glossary
ALCLR Airlock Cooling Loop Recovery
EMU Extravehicular Mobility Unit
EVA Extravehicular Activity
HAP Helmet Absorption Pad
ISS International Space Station
IV Intravehicular
METOX Metal oxide canister
MIB Mishap Investigation Board
PLSS Portable Life Support System
PGS Pressurized Garment System
RCA Rapid Cycle Amine
SWME Spacesuit water membrane evaporator

About the EMU aka Spacesuit
EMU (Extravehicular Mobility Unit)
provides a life support system for the
crew member. It is a self-contained,
pressurized environment with:
• Temperature control
• Oxygen and ventilation
• CO2 and trace contaminant removal
• Protection from space radiation &
debris
• Water for hydration
• Communication with ground and fellow
astronautsPhoto courtesy NASA, obtained from How Stuff Works
In essence, all that’s required for a crew member to survive and work in the hostile
environment of space.

EMU Water Intrusion Anomaly &
Consequences
Water Intrusion Anomaly
• Water intrusion into the helmet
through the ventilation port during
EVA
Consequences
• Safety of the astronaut at high risk
(Luca Parmitano with 1.5 L of water
in helmet)
• Shortened spacewalk. 6.5 hr
reduced to 1hr 45 min.
• Schedule slippage for repairs on
ISS. Fixed number (4) of EMUs
available on-orbit shared among
crew members
• Opportunity cost due to shortened spacewalk:
• Scheduling to replace faulty EMU parts
• Impacted by limited storage space in & flight
schedule of visiting vehicles
• Less opportunity for spacewalks
• Cost of one (1) suit $12M

Spacesuit Sample Schematic

Liquid Cooling Ventilation Garment
(LCVG)
The LCVG is for thermal regulation of the astronaut during EVA.
It is worn underneath the bulky pressurized garment.
Photo credit – Wikipedia

Portable Life Support System (PLSS) –
Advanced EMU
Off-nominal CO2
sensor reading
seems to be a
symptom,
although it had
been ignored
Water found here
Water found here
Water found here

Incumbent Fan/Pump/Separator
• ISS PLSS has the functions of the ventilation fan, cooling
water pump and 2-phase separator combined into one unit
sharing a single motor. This is the Fan/Pump/Separator.
• Apollo PLSS had a separate fan and pump
• Saves 10 W of power

Fan/Pump/Separator Failure History
A total of 96 failures due to each component: fan, pump and water
separator individually.

Part Failure mechanism Fixes
Fan Corrosion of Hall Effect Device
exposed to moist ventilation
loop.
Retrofit to separate the stator from the
armature and the ventilation loop.
Potential corrosion of the fan bearings
which are exposed to the ventilation
loop.
Water
pump
Thermal rotor growth from
internal corrosion of the
permanent magnet potting
within the rotor. This caused an
↑ thermal loop contaminants.
Airlock Cooling Loop Recovery
(ALCLR) unit was included to remove
contaminants of from the thermal
loop.
2-phase
Separator
Blockage due to contaminants
from upstream ALCLR
Inline monitoring of water conductivity
and more frequent monitoring of pH
Evaluation of replacement of biocide
and biocide filter are underway
Fan/Pump/Separator Failures

Water intrusion was due to blockage of pitot phase separator by silica particles from
contaminated ALCLR beds. Condensate was prevented from being fed to the pitot
and forced back into the feedwater bladders causing
1. Overflow from a portion of the slurry fed from the gas trap which drifted into the
fan volute
2. Excessive sublimator carryover (condensed ventilation loop moisture not picked
up by the sublimator slurper which migrates beyond the sublimator in the
ventilation loop)
These two sources contribute excess free water in the ventilation loop ~ 15 mL/min.
Objective 1: Understand source of the water

Objective 2: Identify Source of Silica in
Phase Separator
Biocide filter. Located upstream of the ion exchange resin bed. Currently lignite-
based activated carbon. This is a mined component. We think that it is a possible
source of SiO2 contamination.
Biocide filter

What NASA is doing
Approaches
Excess moisture
in ventilation loop
Mitigate water intrusion
events & causes
ISS EMU
• Helmet absorption pad (HAP)
• ALCLR
• water quality monitoring
(conductivity & pH) &
maintenance
• Replace lignite activated carbon
biocide filter with synthesized
organic filter
• Change biocide from iodine to
silver
• Loading of resin beds
• Water pump redesign?
Advanced EMU
• separation of
fan/pump/separator functions

ALCLR fixes
1. Eliminate silica source
2. Biocide - Change of iodine to silver. Chlorine is known to cause stress corrosion
cracking in steel pipes and iodine is known to cause stress corrosion in
aluminum, titanium and zircaloy.
ISS PLSS fixes
1. Institute alarm for excess water in ventilation loop. Either pay attention to “CO2
Sensor Bad” alarm in suit or create specific alarm for low flow water in ventilation
loop.
2. Redundant fans and pumps like in the Russian Orlan-M
Future Work
1. Avoid excess water in the ventilation system by thoughtful separation of the
ventilation and thermal loops
2. Redundant fans and pumps
Objective 3: Propose Recommendations

References
1. International Space Station (ISS) EVA Suit Water Intrusion – High Visibility Close
Call, IRIS Case Number: S-2013-199-00005, December 20, 2013 (Mishap
Investigation Board Report)
2. J. Steele, T. Elms, B. Peyton, T. Rector, M. Jennings, “Redesign of the
Extravehicular Mobility Unit Airlock Cooling Loop Recovery Assembly”, 46th
International Conference on Environmental Systems, 10-14 July, 2016, ICES-
2016-[221]
3. C. Campbell, “Shuttle/ISS EMU Failure History and the Impact on Advanced EMU
Portable Life Support System (PLSS) Design”, 45th International Conference on
Environmental Systems, 12-16 July, 2015, ICES-201-[327]
4. B. Conger, C. Chullen, B. Barnes, G. Leavitt, “Proposed Schematics for an
Advanced Development Lunar Portable Life Support System”, American Institute
of Aeronautics and Astronautics
5. “NASA publishes Findings of Investigation into Space Suit Water Leak”, February
26,2014Spaceflight 101 Space News and Beyond,
http://www.spaceflight101.net/eva23emuwaterintrusionmishapreport.html
6. https://en.wikipedia.org/wiki/List_of_International_Space_Station_spacewalks

Keisha Antoine, PhD, PE
Antoine Technical Consulting, LLC
Keisha@antoinetech.com
Yvonne Vigue-Rodi
Adelante Sciences Corporation
Yvonne.Viguerodi@adelantesciences.com

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