….designing a smart suit for the Moon and Mars
L.H. Kuznetz, PhD
EVA Physiology, Systems and Performance Project
USRA-NASA JSC
August 27, 2009

“If you’re spending billions to return to the Moon and go to
Mars, you better define mission success and optimize it”
• Mission Success= f (productivity, crew safety)
– Productivity= f (total EVA time, surface area covered)
• EVA time depends on
–
Consumables
–
Suit design
– Traverse management
• Surface area covered depends on
– Working, walking, running speeds
– Metabolic rate
– Work efficiency (02 transport cost, task/work indices)

• LEGACI
– Lunar/Mars Exploration Guidance Algorithm and
Consumables Interrogator
– An algorithm to optimize EVA Productivity and Safety
• Developed at JSC in EVA Physiology, Systems, and Performance Project
• VIOLET
– Voice Initiated Operator for Lunar/Mars Exploration Tracking
– The voice of LEGACI
• Developed at NASA-Ames Research Center

• Metabolic rate (4 methods + backup)
– pCO2; Liquid cooled garment temps;O2 tank pressure; Heart rate; Accelerometry
• Energy cost of work tasks on the Moon and Mars
• Consumables remaining
– Portable Life Support System O2, feedwater, battery power & C02 scrub time remaining
• Suit oxygen leakage
– Real time puncture awareness, out of spec suit leaks
• Crew thermal comfort and Heat Storage Countermeasure
– Countermeasure to Cognitive Deficits (CDO)
– Countermeasure to Loss of Tracking Skills (LOTS), hypo/hyperthermia
• Automatic LCG inlet temperature management
– Minimizes crew distraction, consumables use
– maximizes crew safety and productivity
• Environmental heat leak management
– Real time thermal assessment and excessive albedo avoidance

• EVA Surface Time remaining
– Time management, Traverse goal management, science prioritization
• Guidance and navigation help back to habitat
– Walkback emergency management
• Speed required, distance and time remaining to get back safely
• Redundancy/ self-checkout
– 41 node man running real time in the background
• Alarms
– Excessive sweat
– Excessive metabolic rates
– Excessive heat storage
– Low consumables (O2, feedwater, battery power, CO2 scrubber)
– Excessive suit leak
– Low suit pressure
– High pCO2
– Nutrition required warning
– Hydration (drinking) required warning
– Radiation warning (desirable add on)

• Provide instantaneous information to crew on EVA status
• Relieve crew of unwanted visual distractions
–VIOLET audio feedback less disruptive, more comforting
• Relieve crew of active thermal management (auto lcg option)
• Provide suit autonomy from ground
• Reduce ground support requirements
• Enhance crew safety

• Crew health and safety are paramount
• Apollo had close calls we must avoid

• 16 incidents ≤ 10% remaining
• 11 incidents ≤ 8% remaining
• 3 incidents ≤ 5% remaining
• 1 incident = 2% remaining

• Real time metabolic rate, consumables management and traverse guidance algorithms
• Used PLSS 02, LCG and Heart rate data
• Joint project between SLSD, CTSD, MOD
• Managed all EVAs in real time from MOCR
– MAT (Metabolic Assessment Team)
• Provided only information known about work tasks on lunar surface

The Apollo Metabolic Assessment Team (MAT)
Thermoregulatory flight monitoring and control during Apollo EVAs

Apollo Program Results: Metabolic Rate versus tasks on the Lunar Surface

Crew safety and traverse management: Apollo 17 and 15

This capability has been lost and must be restored

LEGACI and VIOLET: The next generation algorithm
Met Rate 1
Met Rate 2
Met Rate 3
Accelerometer
Met Rate
LEGACI and VIOLET
Accelerometer Data
Met Rate 5
‘Best’ Met
Rate
• Consumables Management
• Guidance & Navigation
• Biomedical Status & Alerts
Met Rate 4
Heart Rate
Heart
Rate
User- Prompted
1.
Metabolic rate
2.
Time for return to base
3.
Time remaining and limiting consumable
4.
Heart rate
5.
Consumables Utilization
Efficiency
(Planned vs. Actual)
Alerts
1.
Acute and chronic overheat / overexertion alert
2.
Suit leak alerts and time of useful consciousness
3.
Recharge alerts
(Met rate, EVA Nav & Guidance)
4.
Walkback range alerts
5.
Environmental heat load advisory
6.
Nutrition & hydration advising?

• What is metabolic rate?
– Energy production at macro (muscular) level
– Energy production at micro (cellular) level
Respiration Equation
C
6
H
12
O
6
+ O
2
= CO
2
+ H
2
O + heat + work
Glucose uptake
(calories burned)
Oxygen uptake C02 production
Heat or work production
• How is it measured?
Respiration equation – requires CO2, O2, RQ, caloric intake
Direct calorimetry--heat balance from liquid cooling garment
Indirect functions: heart rate, movement (accelerometry, IMUs
USING MULTIPLE MET RATES : REDUCES ERRORS
FILLS IN MISSING DATA GAPS
( heat storage, heat leak, suit leak)

1. Metabolic Rate is like Horsepower
2. EVA Consumables are like gas
3. Gas mileage is a function of suit design
4. Productivity and Mission Success depend on 1-3
How much??

QConvection to gas stream
Q Latent evaporation
Q Radiant
Heat leak
QLCG
METABOLIC RATE AND LIFE SUPPORT CONSUMABLES
Feedwater
Boil off rate
Q Metabolic
Q electrical load Q LiOH Heat

8400
7200
6000
slow down, skip station or terminate early
Nominal plan
Consumable depletion line
4800 add science, extend EVA
3600
2400
1200
EVA length: 5.2 hrs 6.6 hrs 9 hrs
1 2 3 4 5 6 7 8
EVA time, hours

The Exploration Envelope:
How far you can go = f (met rate)= f (suit design)
3 km
6, 8 km/hr

LEGACI & VIOLET at work: Suit Test 2, NASA JSC

NASA Johnson Space Center
Crew and Thermal Systems Division
EVA and Spacesuits Systems Branch
TEST AREA LAYOUT (EVA Exploration tasks)
North suit biosensors (7)
Suit Cooling
System
UTAF
Video
Monitor
2
O
C
AQ
D
Suit
Donning
Area
Motion
Capture/EVA
Exploration
Task Area
Indicates Camera Location
Treadmill
POGO
Instrumentation
Console ill
Tr ea dm
C on tr ol s/
D is pl ay
Motion
Capture DAQ
& Displays

• Note: the following graphs demonstrate the algorithm’s capabilities, and represent a mixture of real time results, modeled LEGACI output and examples. For privacy purposes, the data should not be construed as unique to any test subject or individual participating in IST-2.

6000
5500
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
0.00
50.00
100.00
150.00
200.00
250.00
Met rate, HR
Met rate O2 met rate pC02
Met rate, LCVG
MR avg all
Best Logic

Cum metrate:
Caution: 02 cum >> HR cum indicates possible suit leak
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
0 50 100 150 200 250 time, minutes
300 350 400 450 cum 02 pC02 cum
HR cum
LCVG cum
500

1.0
0.8
0.6
0.4
0.2
0.0
0.00
Sweat Vs. T ime
50.00
100.00
T i me, mi nutes
150.00
200.00
250.00
Sweat, RH1
Sweat, 41 NodeMan

4500.000
4000.000
3500.000
3000.000
2500.000
2000.000
1500.000
1000.000
500.000
0.000
0.00
-500.000
LCG heat deficit, heat storage rate, CDO* and LOTS** alarms
LCG Heat Removal Vs Prediction (08-01-2007)
50.00
100.00
150.00
EVA time, minutes
200.00
250.00
300.00
Legaci
41 Node Man met rate vs LCVG cooling
3000
2000
1000
0 met rate lcvg Q removal time, minutes
*Cognitive deficit limit
**Loss of tracking skills est heat stored vs time
300
200
100
0
0 20 40 time, minutes
60 80
CDO
Series1

worst case consumable use
500.00
300.00
100.00
-100.00
0.00
60.00
120.00 180.00 240.00 300.00
time, minutes

Example of consumables remaining computation
Portable Life Support System (PLSS) feedwater:
(from HR (blue) and lcvg (pink)
Caution: redlines computed using zero heat leak. Hot albedo will reduce time remaining
0 50 100 150 200 250 300 350 400
EVA time, minutes

Heat transfer rate out of suit, Btu/hr
O2 leakage rate out of suit, cc/minute
300
200
100
0
0 50 100 150
EVA time, minutes
200 250

• Optimizes the human/suit interface
• Prevents heat storage buildup
• Frees crew of manual diverter valve changes
– Apollo 17 EVA 2 CDR: 20 changes
– Apollo 16 EVA 1, CDR: 9 changes
– Apollo 16 EVA 1, LMP: 9 changes
– Apollo 12 EVA 2, CDR: 9 changes
• Manual override or audio guidance available
• Control can be individualized to user
– Metabolic rate, heart rate or heat storage driven

Met rate driven
Tin (degrees F) =
100.4- .0282 * metabolic rate met rate in
BTUs/hr
Heat storage driven
Tin (degrees F) =
60 - .08333 * heat storage
Heat storage in
BTUs
Heart rate driven
Tin (degrees F) =
C1 HR + C2
(c1, c2 are constants)
Default Logic
(equal contributions from each mode)
T inlet = 0.33 (100.4 - .0282 * metabolic rate) + 0.33 (60 - .08333 * heat storage) + 0.33 (C1 – C2 *HR)

Humans are notoriously poor judges of their own thermal state
– Estimated fatalities/year
• 150,000 worldwide from hyperthermia in 2003 (source WHO)
• 688 deaths/year US (source (CDC 2006)
• 689/yr US from hypothermia (3 per 100000 in Alaska, CDC 2005)
• Hospitalizations exceed 10,000/year
– Many high school football, wrestling injuries due to heat
– $1 B lawsuit against NFL in Cory Stringer case
– Mild hypo/hyperthermia compromises judgment, tracking skills
– Applicable examples to EVA astronauts?

9 0 . 0
8 0 . 0
7 0 . 0
Selected LCG inlet temp
6 0 . 0
5 0 . 0
Optimum LCG inlet temp
4 0 . 0
3 0 . 0
0 . 0 0 5 . 0 0 10 . 0 0 15 . 0 0 2 0 . 0 0
EVA time, minutes
2 5 . 0 0
Potential Consequence:
1. Elevated sweat rate
2. Elevated heat storage
3. Cognitive deficit
4. Human System Performance impairment
3 0 . 0 0 3 5 . 0 0 4 0 . 0 0

9 0 . 0
8 0 . 0
7 0 . 0
6 0 . 0
5 0 . 0
4 0 . 0
3 0 . 0
0 . 0 0 5 0 . 0 0 10 0 . 0 0
EVA time, minutes
15 0 . 0 0
Potential Consequence:
1. Delayed onset of sweating
2. Minimal sweat rate
3. Excessive consumables (feedwater)
4. Potential impact to LiOH system (dryout)
5. Elevated pC02
Optimum LCG inlet temp
1.0
0.8
0.6
0.4
0.2
0.0
0.00
Selected LCG inlet temp
2 0 0 . 0 0
50.00
2 5 0 . 0 0
Sweat Vs. Time
100.00
150.00
Tim e, m inutes
200.00
250.00
3 0 0 . 0 0
300.00

Optimum LCG inlet temp
0.00
50.00
100.00
EVA time, minutes
150.00
Selected inlet temp
200.00

• Promotes crew safety
– Humans are poor judges of their own thermal state
• Manual undercooling can compromise judgment
• Manual overcooling can compromise suit performance
• Saves consumables
• Max LCG cooling uses more feedwater then Min
• May reduce up-mass and cost over time

• Human body/spacesuit simulator
• Embedded in LEGACI logic
• Runs and updates predictions in real time
• Pedigree of accurate predictions dating to Apollo
• Provides real time correlations to LEGACI
• Provides backup if biosensors fail
• Provides information not available on LEGACI
– Suit thermal heat leak
– Suit temperatures
Heat Transfer Rate
166
– Body temperatures
164
162
160
Q Thru Suit
158
156
154
152
0.00
50.00
100.00
150.00
200.00
250.00
minutes

LEGACI and VIOLET will provide the following
• Real time instantaneous EVA status, warnings and advisories
–Consumables remaining
–Physiological advisories (nutrition, hydration, heat storage)
–Guidance and navigation (position, speed, time, distance to safe haven)
–Suit/thermal status (leak rate, radiant environment, heat balance)
• Enhanced accuracy
• Reduction of unwanted visual distractions
–audio feedback (Violet) less disruptive, more welcoming
• Automatic thermal control option (auto lcg)
• Suit autonomy from ground
• Reduced ground support requirements
• Enhanced crew safety

The short answer: trend analysis minivan climbing a hill example

• Dr. Michael Gernhardt, NASA-JSC, project management, funding
• Dr Jeffrey Jones, NASA -JSC, Med Ops input, support,
• Astronaut test subject team
• Integrated Suit Test Team, NASA-JSC
– Grant Bue
– Jill Klein
– Jason Norcross
– Jessica Vos
– Jennifer Tuxhorn
– Jim Wessel
– Jennifer Jadwick
– Nick Skytland

C O M M ANDS
W AK E U P
E V A T IM E
W H AT IS M Y M ET AB O LIC R AT E
H E AR T R AT E C HEC K
LIM IT IN G C O N SUM AB LE
H O W M UC H PO W ER IS L EFT
C O O LIN G ST AT US
W ALK B AC K CH EC K
PLE AS E ST O P T ALK IN G
G O T O SLEEP
W H AT T IM E IS IT
W H AT IS M Y H E AT ST O RAG E
FEED W AT ER C H EC K
H O W M UC H O XYG EN IS LEFT
T ELL M E A JO K E
H O W F AR IS T H E H AB ?
W H AT IS M Y O 2 PR ESSU R E
W ALK B AC K RISK
SH UT U P
SW E AT
C O N SU M AB LE S R EPO R T
H E AT L E AK
SU IT LE AK
R AD IAT IO N D O SE
A LERTS
E XCESSIVE M ET R ATE (>3000 B TU / HR )
E XCESSIVE H E AT S TOR AG E (>+300 BTU S )
30 M INUTES O XYG EN R EM AINING
30 M INUTES F EEDW ATER R EM AINING
30 M INUTES S CRUBBER R EM AINING
30 M INUTES P O W ER R EM AININ G
K C AL ALERT ( E AT )
N UTRITIO N ALERT ( DRINK )
H IG H PC02
L O W SUIT PRESSURE
H IG H HE ART R ATE (>160 BPM )
H IG H HE AT LEAK
H IG H SUIT LEAK (>10 TIM ES SPEC )
H IG H R ADIATIO N DO SE
R ETURN TO H AB, W ALKB AC K EM ERG ENCY
N O T E:
T he above com m ands are part of a voice recognition library. O nly key w ords are
required. T he com m and s do not have to given verbatim as they appear ab ove.

• Initial version complete and operating
• Linked to Ames Voice Recognition system
– Violet
• Rev 1 used in Walk-back Test (500 lines of code)
• Rev 5 used in Suit test 1
• Rev 15 used in Suit test 2
• Currently undergoing correlation to test data
• Rev 25 will support future suit tests

• Continued Test Correlation (IST, Thermal Vacuum, field tests)
• Add Path Planning Capability
– IMU (accelerometers)
– Path Planning software for EVA traverse Guidance and Navigation
– Terrain characterization for Traverse modification and safety
• Radiation Dosimeter integration (desirable)
• Biosensor selection and maturation
• Alternative EMU design provision (evaporators, heat sinks, C02)
• Integrated error analysis
• Homologation of Code suitable for GRC Requirements
– Current code: 300000 lines, 1.5 GB, 5 Applications

EPSP
Legaci refinement, homologation and correlation to test data,
Biosensor definition maturation
DEVELOPMENT TIMELINE
Legaci & Violet (rev25)
Requirements definition
MIT?
EVA Path Planner:
IMU, velocity position, EVA traverse re-planner and backup met. rate
EPSP
Engineering breadboard demonstrator
2008
NASA
ARC
Violet
Audio program
Refinement and correlation
2009
2010
2011
2012
Delivery to GRC

Measurement or display LEGACI Requirement
HSIR requirement
Metabolic Rate X X
EVA Consumables Management X
Biosensors
Heart rate X pC02 in helmet X
O2 in helmet or tank pressure
X
LCG inlet temp X
LCG delta temp X
Suit outlet dewpoint
X
Suit outlet gas temperature X
LCG water flowrate X
Suit accelerometers (3)
X
Radiation dosimeters
X
Suit Pressure, gas flow X
Communications Enhancements
Microphones, comm carrier
X
X x x
?
?
X
X
X
X
?
X
X
?