Diving in Space - NASA · PDF file0 30 60 90 120 150 Time (min) 180 0 2 ... Example of Prebreathe Reduction Program (PRP) ISS Overnight ... Pre-Challenger Shuttle Shuttle 50 Diving

Diving in SpaceDiving in Space

Mik G h dtMike Gernhardt

Diving in Space | National Aeronautics and Space Administration | Mike Gernhardt 1

https://ntrs.nasa.gov/search.jsp?R=20090002616 2018-05-09T12:03:01+00:00Z

Biomedical and Technological Challenges of EVABiomedical and Technological Challenges of EVA

• Decompression (denitrogenation required to work in low pressure suit (4.3 psi))

• Thermoregulation (-120oC to + 120oC)g ( )

• Nutrition (200 kcal/hr requirement)

• Hydration (1 liter/EVA)y ( )

• Waste Management

• Radiation

• Micrometeoroids and Orbital Debris

• Suit Trauma

• Mobility/Dexterity: current pressurized suits reduce mobility and dexterity

Visibilit


• Visibility

Type II DCS – Percentage of All DCS vs. Diving MethodsType II DCS – Percentage of All DCS vs. Diving Methods

9 01 0 0

4 05 06 07 08 0

01 02 03 0

l l ic k s A

Comme rc

ia l

R ecreat io

n al

S cien tific

USN Sa fety

Cente

rUSN D

ive Tria

ls

B rook s

NASA

US• Character of Altitude DCS Different from Diving DCS

• Undersaturated Neurological Tissues

From DAN, 2005


• Undersaturated Neurological Tissues

• “Softer Bubbles” Metabolic Gases

Altitude DCS - Nitrogen Elimination during Oxygen PrebreatheAltitude DCS - Nitrogen Elimination during Oxygen Prebreathe

2500

V

V60-90

Cumulative NitrogenElimination(ml)

N 2 e l im in a t io n in 5 a n d 1 0 m in u t e h a lf -t im e c o m p a r t m e n ( ~ b r a in a n d s p in a l

c o r d )1 0

V0-30

V30-60

4

6

8

1 0

030 60 90 120 1500

Time (min)180

0

2

0 2 0 4 0 6 0 8 0

Time ( minutes)

- Over 50% of nitrogen eliminated in first 30 minutes- Brain, spinal cord Halftime ~ 5-10 minutes, muscle and skin halftimes

- 15-25 minutes at resting conditions

Time ( minutes)

- 15-25 minutes at resting conditions - Resting prebreathe reaches point of diminishing return for reducing pain

only DCS- Type II DCS incidence higher on “Zero Prebreathe”


Gerth, W.A., R.D. Vann, N.E. Leatherman, and M.D. Feezor. 1987. Effects of microgravity on tissue perfusion and theefficacy of astronaut denitrogenation for EVA. Aviat. Space Environ. Med. 58(9, Suppl.): A100-105

Shuttle Pre-breathe Ground StudiesShuttle Pre-breathe Ground Studies

Two Pre-breathe protocols approved

• 4 hour in-suit resting oxygen pre-

for flight operation

g yg pbreathe

• 12 hr 10.2 psi staged decompression procedure

• R value ( tissue ( )/tension (360)/suit

pressure)= 1.65


Flight Experience Shuttle 10.2 psi Staged Protocol – Zero DCS Flight Experience Shuttle 10.2 psi Staged Protocol – Zero DCS

120

Time at 10.2 psi prior to 60

80

100

120

Numbe r of EVAs

shuttle EVA

0

20

40

12-16 16-20 20-24 24-144Time (hours)Time (hours)

25

dex

12 hr*

Theoretical Tissue Bubble growth as a function of

10

15

20le

Gro

wth

Ind

0 m

in T

issu

e 12 hr

16 hr*

20 hr*

growth as a function of 10.2 exposure time

0

5

0 100 200 300 400EVA Time (min)

Bub

bl 480

24 hr*


EVA Time (min)

Defining and Controlling Risk in Operational Research Programs – Example of Prebreathe Reduction Program (PRP)Defining and Controlling Risk in Operational Research Programs – Example of Prebreathe Reduction Program (PRP)

ISS OvernightCampout

Enabling Counter Measure Research

( NASA TRL 3/4)Background

40

60

80

100

% D

CS

20/26 (77%)

11/26 (42%)

*Arm & leg work at 75% VO2 max with

seated subjects

p=0.03

0

20

Rest 0:10 Heavy Work*1:00 O2 Prebreathe

USAF prebreathe exercise

Shuttle Prebreathe Ground Trials (~ 25% DCS, ~ 5% symptoms that would

Limitations•Timeline, back to 40

60

80

CS

10/20

Legs (p=0.0008)Arms (NS)

USAF prebreathe exercise

symptoms that would terminate an EVA.) Acceptable Risk?- 4 hour prebreathe- 10.2 psi staged protocol

,back EVAs, •02 usage,ISS 02 concentration•crew isolation and

0

20

40

Ambulatory Non-Amb.

% D

2/203/21

1/21

95% CI


p g p- 146 EVAs exposures with no reports of DCS

comfortDuke, NASA micro-gravity

simulation ( non ambulation)

Enabling ResearchEnabling Research

10 minutes 75% V02peak 88% lower


10 minutes 75% V02peak, 88% lower body, 12% upper body

Prebreathe Reduction ProgramPrebreathe Reduction Program

• Start by defining acceptable DCS risk for ISS mission and developing

Prebreathe ReductionLaboratory Studies-5 Year Operational developing

accept/reject limits for countermeasure trials

• Early development

-5 Year OperationalResearch Plan

Integrated DecompressionStress Predictive Model

Early development focused on delivering acceptable/effective counter measure

AcceptableDCS RiskDefinition

2 Hr.Prebreathe

Protocol

1.5 Hr.Insuit

Prebreathe

Relationship between

Micro-g sim. andexercise

Break inPrebreathe

Studies

SupportingStudies

• Later development focused on increased efficiency and improved scientific

Phase 1 √

Phase 2 √

Phase 3 √

Phase 4 √

Phase 5.1 **

Phase 5.2

Phase 5.3

Phase 5.4

Brooks Studies *

adynamia cross over study

JSC

Phase 6.1

Phase 6.XX

- Lactate measurements

- Oxygen Consumption *

- Cardiac Output

- Blood flow

- Nitrogen Elimination

scientific understanding of counter measure mechanisms

Phase A **

EVA exercise simulations


Accept: DCS Accept: DCS << 15% and Grade IV VGE 15% and Grade IV VGE << 20% , @ 95% 20% , @ 95% C.lC.lReject: DCS Reject: DCS >> 15% or Grade IV VGE 15% or Grade IV VGE >> 20% , @ 70% 20% , @ 70% C.lC.l

Multi-Center Study: NASA, Duke, DCIEM, Hermann UTMulti-Center Study: NASA, Duke, DCIEM, Hermann UT

2hr oxygen prebreathe

Exercise 10 mins @ 75% V02peakAnd/or light exercise (160-253 Kcal/hr)

Micro-gravity simulation( non-ambulation)


Simulated EVA exposure at4.3 psi 4 hrs Use of “Suit Simulator” for

EVA Exercise

Prebreathe TrialsPrebreathe Trials1010 DCSDCSPhase I

Phase II

Ph III

40 min40 min

LightLight

RestRest

RestRest

RestRest

1010minmin75%75%

VOVO2 peak2 peak

4 hr4 hr

EVAEVA

SimuSimu--

DCSDCS19%19%

0%0%

22%22%Phase III

Phase IV

ActivityActivityRestRest

RestRest95 min Light Activity95 min Light Activity

SimuSimu

lationlation

22%22%

14%14%

PRP Phase I-IV 2 hr oxygen prebreathe exercise protocols

60

70

80

DCS

DCSVGEn=47

n=9• High intensity exercise (75% peak oxygen

20

30

40

50

60DCSor

Grade IVVGE(%)

n=56

n=45

(75% peak oxygen consumption [VO2 peak])

• Low intensity activity (5.8 mL·kg-1·min-1 VO2)

0

10

I II III IVPhase

( g 2)

• Neither High or low intensity exercise was acceptable

C li Hi h ith DCS and Grade IV VGE observations (shown with 95%


• Coupling High with low intensity exercise was acceptable

DCS and Grade IV VGE observations (shown with 95% upper confidence limit bars dashed lines indicating accept levels for DCS and VGE incidences)

Exercise and Inert Gas KineticsExercise and Inert Gas Kinetics

P1N2 = P0 + (1 - exp – k1t ) * (Pa - P0),

k1 = [(1 / exp (-λ * mL*kg-1*min-1)) / 519 37]k1 = [(1 / exp (-λ mL kg-1 min-1)) / 519.37].

Model Predictions vs Actual

20

25

30

35

0

5

10

15

20%DCS

I II III IV V 1 V 3 V 4I II III IV V-1 V-3 V-4

PRP Trials

Hosmer-Lemshow Goodness of fit statistic = 2.188 with 5 degrees of freedom, p = 0.82 ( significance > .05)


Exercise Prebreathe Protocol: Experience to DateExercise Prebreathe Protocol: Experience to Date

• Overview- The exercise prebreathe protocol has been used successfully on 34 EVAs from the International Space Station (ISS)- no DCS

• Five Shuttle assembly flights and two increment EVAs• Starting in July 2001• Starting in July 2001

• These assembly missions would have been difficult or impossible to execute as base-lined, without the protocol


A United States Airlock: Doorway to SpaceA United States Airlock: Doorway to Space

U.S. “Quest” Airlock


The Challenge of Moving Past ApolloThe Challenge of Moving Past Apollo

A ll k bl h hi t• Apollo was a remarkable human achievement

• Fewer than 20 EVAs, maximum of three per mission

• Constellation Program up to 2000 EVAs over• Constellation Program, up to 2000 EVAs over the 10 year Lunar program

• Limited mobility, dexterity, center of gravity and other features of the suit required significant crew compensation to accomplishsignificant crew compensation to accomplish the objectives. It would not be feasible to perform the constellation EVAs using Apollo vintage designs

• The vision is to develop an EVA system that isThe vision is to develop an EVA system that is low overhead and results in close to (or better than) one g shirt sleeve performance i.e. “ A suit that is a pleasure to work in, one that you would want to go out and explore in on your day off”day off

• Lunar EVA will be very different from earth orbit EVA – a significant change in design and operational philosophies will be required to optimize suited human performance in lunar


opt e su ted u a pe o a ce u agravity

Challenges for EVA on the MoonChallenges for EVA on the Moon• Dealing with risk and consequences of a significant Solar Particle Event g q g

(SPE) • Long duration missions with three 8hr EVAs per person per week

– Apollo suits were used no more than 3 times– Individual crewmembers might perform up to 76 EVAs in a 6-month missionIndividual crewmembers might perform up to 76 EVAs in a 6 month mission– Suit-induced trauma currently occurs with even minimal EVA time

• With Apollo style un-pressurized rover (UPR), exploration range is limited by EVA sortie time and 10 km walkback constraint

– Science community input that optimal scientific return within this range could be– Science community input that optimal scientific return within this range could be accomplished within ~ 30 days of EVA

– Two UPRs could extend exploration range up to 15-20 km (crew-day limited)• Apollo highlighted the importance of dust control for future long duration

missions• Increased Decompression Sickness (DCS) risk and prebreathe requirements

associated with 8 psi 32% O2 cabin pressure versus Apollo with 5 psi 100% O2

• The high frequency EVA associated with the projected lunar architectures g q y p jwill require significant increases in EVA work efficiency (EVA prep time/EVA time)


“The Wall of EVA”“The Wall of EVA”“The Wall”

250

ISS Construction (projected)

“The Wall”

200

150

A H

ours

100EVA

GeminiApollo/Skylab

Pre-ChallengerShuttle Shuttle

50Apollo/Skylab


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“The Mountain of EVA”“The Mountain of EVA”

5000“The Mountain”

3500

4000

4500 Available Lunar EVA Hours (LAT-2 Option 2) – based on Three 8 hour EVAs per week using Unpressurized Rovers

2500

3000

3500

A H

ours

g pNeed to extend range well

beyond 10 km

1500

2000EV

A

Gemini “The Wall”

500

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Gemini

Apollo/Skylab Pre-ChallengerShuttle

Shuttle


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Intermittent Recompression - BackgroundIntermittent Recompression - Background

C t l f l f• Current plans for lunar surface exploration include Small Pressurized Rovers (SPRs) that are quickly ingressed and q y gegressed with minimal loss of consumables

• This capability enables crew members to perform multiple short extravehicular activities (EVAs) at different locations in a

9Recompression(EVAs) at different locations in a

single day versus a single 8-hr EVA

5

6

7

8

psia

)

Cabin Pressure

p

• Previous modeling work and empirical human and animal data indicate that the intermittent recompressions may reduce

2

3

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Pres

sure

(p

EVA EVASuit

Pressure


recompressions may reduce decompression stress

0

1

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Time (hours)

Tissue Bubble Dynamics Model (TBDM)- Provides Significant Prediction and Fit of Diving and Altitude DCS DataTissue Bubble Dynamics Model (TBDM)- Provides Significant Prediction and Fit of Diving and Altitude DCS Data

• Decompression stress index based on tissue bubble growth dynamics (Gernhardt, 1991)

• Diving: n=6437 laboratory (430 DCS cases)– Logistic Regression Analysis: p <0.01

H L h G d f Fit 0 77– Hosmer-Lemeshow Goodness of Fit = 0.77 • Altitude: n=345 (57 DCS, 143 VGE)

– Logistic Regression Analysis (DCS): p <0.01 – Logistic Regression Analysis (VGE): p <0.01 – Hosmer-Lemeshow Goodness of Fit (DCS): p = 0.35Hosmer Lemeshow Goodness of Fit (DCS): p 0.35– Hosmer-Lemeshow Goodness of Fit (VGE): p = 0.55

r = Bubble Radius (cm)t = Time (sec)t = Time (sec) a = Gas Solubility ((mL gas)/(mL tissue))D = Diffusion Coefficient (cm2/sec)h(r,t) = Bubble Film Thickness (cm)Pa = Initial Ambient Pressure (dyne/cm2)v = Ascent/Descent Rate (dyne/cm2⋅cm3)g = Surface Tension (dyne/cm)M = Tissue Modulus of Deformability (dyne/cm2⋅cm3)


M Tissue Modulus of Deformability (dyne/cm cm )PTotal = Total Inert Gas Tissue Tension (dyne/cm2)Pmetabolic = Total Metabolic Gas Tissue Tension

Gernhardt M.L. Development and Evaluation of a Decompression Stress Index Based on Tissue Bubble Dynamics. Ph.D dissertation, University of Pennsylvania, UMI #9211935, 1991.

Intermittent Recompression - BackgroundIntermittent Recompression - Background

• Intermittent recompression during saturation decompression was previously proposed as a method for decreasing decompression stress and time (Gernhardt,1988)

– Gas bubbles respond to changes in hydrostatic pressure on a time scale much faster than the tissues

• Intermittent recompression (IR) has been shown to decrease decompression stress in humans and animals (Pilmanis et al. 2002, Møllerløkken et al. 2007)

6437 laboratory dives (430 DCS cases)

Gernhardt, M.L. Mathematical modeling of tissue bubble dynamics during decompression. Advances in Underwater Technology, Ocean Science and Offshore E i i V l 14 S b ibl T h l S i t f U d t T h l 1988


Engineering, Volume 14: Submersible Technology. Society for Underwater Technology, 1988.Pilmanis A.A., Webb J.T., Kannan N., Balldin U. The effect of repeated altitude exposures on the incidence of decompression sickness. Aviat Space Environ Med; 73: 525-531, 2002.Møllerløkken A, Gutvik C, Berge VJ, Jørgensen A, Løset A, Brubakk AO. Recompression during decompression and effects on bubble formation in the pig. Aviat Space Environ Med; 78:557-560, 2007.

DiscussionDiscussion

A

BB

20

8101214161820

Gro

wth

Inde

x59% DCS

02468

0 100 200 300 400Time (min)

Bub

ble

6% DCS


Pilmanis A.A., Webb J.T., Kannan N., Balldin U. The effect of repeated altitude exposures on the incidence of decompression sickness. Aviat Space Environ Med; 73: 525-531, 2002.

DCS Incidence TBDM PredictionsTime (min)

Intermittent Recompression - 3 x 2hr EVA at 4.3 psiIntermittent Recompression - 3 x 2hr EVA at 4.3 psi40

35

40

25

30

dex

(BG

I)

0 5hr between 2hr EVAs

6hr Continuous EVA

20

Gro

wth

Ind 0.5hr between 2hr EVAs

1hr between 2hr EVAs2hr between 2hr EVAs

10

15

Bub

ble

G

3hr between 2hr EVAs

0

5


00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Time (hours)

Floating Through the Terminator in the Sea Space ContinuumFloating Through the Terminator in the Sea Space Continuum


Slide TitleSlide Title


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Diving in Space - NASA · PDF file0 30 60 90 120 150 Time (min) 180 0 2 ... Example of Prebreathe Reduction Program (PRP) ISS Overnight ... Pre-Challenger Shuttle Shuttle 50 Diving