Apollo Experience Report Assessment of Metabolic Expenditures

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C O P Y

APOLLO EXPERIENCE REPORT -ASSESSMENT OF METABOLIC EXPENDITURES

J . M . Wuligoru, W , R. Huwkins, G . F . Humbert,

L. J . Nelson, S. J . Vogel, and L . H . KEcznetz

Lyndon B . Johnson Space Center

Houston, Texus 77058

N AT I O N A L A E R O N A U T I C S A N D S PA C E A D M I N I S T R AT I O N WA S H I N G TO N ,D. C. M A R C H 197



1. Report No.

NASA TN D-7883

APOLLOEXPERIENCEREPORTASSESSMENT O F METABOLIC EXPENDITURES

2. Government Accession No. 3. Recipient's Catalog No.

March 1975

6. Performing Organization Code

4. Title and Subtitle 5. ReDort Date

Lyndon B. Johnson Space CenterHouston, Texas 77058

7. Author(s)

J. M. Waligora, W. R. Hawkins, G. F. Humbert, and L. H.Kuznetz, JSC, and L. J. Nelson and S. J. Vogel, Boeing Company

9. Performing Organization Name and Address

11 . Contract or Grant No.

JSC-074848. Performing Organization Report No.

JSC S-394Work Unit N o,

914-50-95- 3-72

13. Type of Report and Period Covered

Technical Note. Sponsoring Agency Name and Address

14. Sponsoring Agency Codeational Aeronautics and Space AdministrationWashington, D. C. 20546

7. Kev Words (Suggested by Authork)Heart Rate

* Oxygen Consumption* Liquid-Cooled Garment- Energy Levels-Extravehicular Activities

I

5. Supplementary Notes

18. Distribution Statement

STAR Subject Category:12 (Astronautics, General)

6. Abstract

A significant effort was made to a ss es s the metabolic expenditure for extravehicular activity onthe lunar surface. After evaluation of t he real -ti me dat a availa ble to th e flight con troll er duringextravehicular activity, thr ee independent methods of metabolic ass ess men t were chosenbased on the rel ation ship between hea rt ra te and metabolic production, between oxygen consump-tion and meta boli c production, and between the thermod ynam ics of th e liquid-cooled gar men tand metabolic production.Real -tim e u se of t his informati on by the Apollo flight surgeon is discussed. Results and analy-ses of the Apollo missions and comments concerning futur e applications a r e included.

The metabolic assessment procedure is analyzed and discussed.

19. Security Classif. (o f this report) 20. Security Classif. (of this page) I21. NO. ;pages 22 . Price

Unclassified Unclassified I $3.25

* For sale by the National Technical Information Service, Springfield, Virginia22151



APOLLO EXPERIENCE REPORT

EDITORIAL COMMITTEE

The mater ial submitted fo r the Apollo Experience R epo rts(a series of NASA Tec hnic al Notes) wa s reviewe d and ap-proved by a NASA Editorial Review Board at the Lyndon B.Johnson Space Cente r consi stin g of th e following mem be rs :Scott H . Simpkinson (Chairman), Richard R . Baldwin,Ja me s R. Bates , William M. Bland, J r . , Aleck C. Bond,Robert P. Burt , Chris C. Critzos, John M. Eggleston,E. M . Fields, Donald T. Gregory, Edward B. Hamblett, J r . ,Kenneth F. Hecht, David N . Holman (Editor/Secretary),and Car l R. Huss. The pr im e reviewer fo r this report

was Donald T. Gregory.



APOLLO EXPERI ENCE REPORT

ASSESSMENT OF ME TAB OLIC EXPENDITURES

B yJ . M. Waligora, W . R . Hawkins, G. F. Humbert,L. J. Nelson,* S . J. VogeI," and L. H. Kuznetz

Lyndon B . Johnson Space Center

S U M M A RY

Before the first Apollo extr aveh icul ar activity, the staff of the NASA Lyndon B.

Johnson Space Center (formerly the Manned Spacecraft Center) developed operationalmethods to deter mine the energy expenditures of the crewmen. Thes e methods wer ereq uir ed to allow adequate physiological evaluation of the crewme n, to determi ne theusage r at e of life-support syste m consumables, and to provide information for r eal -time activity scheduling and fo r planning future missions.

Th re e independent methods were used to determine crewmen energy expenditures.The heart -rate method w a s based on the d irec t linear relationship between energy ex-penditure and heart rate, which w a s dete rmine d befo re each flight. The oxygen methodwas based on the proven clinical procedu re that r ela tes energy expenditure to oxygenconsumption. The liquid-cooled-ga rment method w a s based on a modified directcal ori met ric approach to energy measurement. Preflight testing of these methodsdemonstrated inadequacies and inaccuracies that were co rrect ed, and a system wasdeveloped that facilitated integratio n of the thr ee methods into an acc urat e est imate ofenergy expenditure.

During each extravehicular activity, this integrated estimate w a s reported to themissi on control flight surgeon and to the life-support sys tem monitors. Thus, t heflight. surgeon was pr epa red to make recommendations concerning the immediate andfu tu re well-being of the crewm en. Postfligh t anal yses of the re su lt s, combined withmotion analy sis, permi tted accura te asse ssm ent s of energy expenditure for specificluna r sur fac e tas ks. It was concluded that these methods provided reliab le information

3 3on crewmember energy expenditures, which ranged from 822 X 10 to 1267 X 10 J / h r(780 to 1200 Btu/hr) fo r the Apollo lunar surfa ce extravehicula r ac tivities.

%oeing Company.



INTRODUCTION

Information about energy expenditure at the onset of planning fo r Apollo e xtra ve-hicular activity (EVA) w a s meager. The observations made during the Gemini EVAperi ods indicated that the energy expenditures wer e great er than expected. The basisfo r the comparison was the heart ra te s observed during altitude chamber simulations

and those observed during the actu al EVA. The gre ate st deviation between the expectedhe ar t rat es and the observed heart r a te s occ urr ed during the Gemini XI EVA. Insteadof providing a quantitative meas ureme nt of met abol ism, the se observa tion s only indi-cated that at times the metabolic r at es we re more than the life-support syst em couldaccommodate. Data wer e available fr om 1/6-g tr ai ne rs of many types; however, t her ew a s a gener al lack of confidence i n thi s type of lun ar s urf ace sim ulat ion, par tic ula rlywhen the data were applied to energy expenditures for movement on the unknown terrainof the lunar surf ace .

A measurement of crew metabolic ra te s w a s required for several reasons. Thebasic measurement was import ant to the flight surgeon because it provided a measureof how closely a crewman w a s approaching hi s maximum work ra te either acutely, as

during a maximum effort when a c rewma n's maximum oxygen consumption might beexceeded, o r chronically, as when a susta ined moderately high work r at e might lead toexhaustion. The metabolic ra te al so provided data that could affect the flight surg eon' sevaluation of othe r information rega rdin g a crewman . For example, a hea rt r at e of130 beat s/mi n would indicate one level of conc ern for a crewman vigorously at workand another for a crewman at res t .

The metabolic ra te measurement was al so important to the monitors of the port-able life-support syst em (PLSS) because the useful life of a PLSS on the lunar surfacedepended on the usag e ra t e of c onsu mabl es (oxygen, subl imat or wate r supply, andcarb on dioxide abso rber ). The usage rat e of the se consumables is closely related tometabolic rate; t h i s relationsh ip was particu larl y significant in the cas e of the water

supply to the sub limator that provided the cooling for t he PLSS because t he re w a s nomeasurement of sublimator water supply.

The metabolic ra te mea surement provided essen tial information for t he lunarsurf ace activity plan ners who ass emble d a schedule of crew ac tivi ties based on preflightestimations of the metabolic expenditure and the tim e requ ired to perfor m each activity.Thes e planners were respo nsible for modifying the crewman's activity in re al ti me ifthe metabolic expenditures for the activities o r the time required to perf orm the activi-tie s deviated from the predicted values.

Before the fi rs t Apollo EVA, se ve ra l gro ups a t the NASA Lyndon B. Johnson SpaceCenter (JSC) formerly the Manned Spacecraft Center (MSC)) had been concerned withmetabolic rates . A medical operations group was responsible f o r providing metabolicrate estimates f or specific tasks and fo r monitoring the crew during 1/6-g training atMSC; a medical rese arc h group provided the metabolic req uirem ents for the design ofthe life-support system and sponsored several research programs to evaluate various1/6-g simulations. An engineering group attempted to us e hea t-l oss data f ro m theliquid-cooled garment ( L C G ) to es timat e metabolic ra te i n calculating the usage of sub-limat or water supply. In 1969, before the f i r s t Apollo EV A (on the Apollo 9 mission),

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the Life Sciences Directorat e formed a Metabolic Assessment Team that w a s composedof pe rsonnel fr om the Life Scienc es Director ate and a member fr om the Engineeringand Development Di rect orat e, all of whom had been working i n the a r e a of metabol ism.The team also benefited fr om support received fr om the Mission Evaluation Team andoth er MSC groups. The Metabolic Asse ssme nt Te am w a s charged with the responsi-bility f or reviewing and evaluating real -tim e data that would be avai labl e during EVAand for devising procedure s to use these data i n measuring the crewman's metabolicrates dur ing EVA.

A s a res ult of the team's initial stud ies, t hre e independent methods based on themost common laboratory methods were implemented:

1, The relationship between heart rate and metabolic rate

2. The relation ship between oxygen consumption and metabolic ra te

3 . The relationship between the heat removed fr om the crewman by the LCG andmetabolic rat e

Each method w a s used during ground-based tes ts and each w a s found to provide usefuldata but to have deficiencies when used alone.methods and the real-time modifications made to improve them ar e presented i n thefollowing sections.

The advantage s and deficie ncies of t hes e

HEART-RATEMETHOD

Hear t r at es wer e used during Apollo flights to estim ate metabolic expendituresduring specific extravehicular activities. Because the hear t ra te is an indicator of

total physiological and psychological stress, it is not entirely dependent on metabolicrate. The hear t-ra te method w a s , however, the only method with a timelag shortenough to allow a minute-by-minute est ima te of the energy expendi ture.

In addition to the inac cura cies (psychogenic fac tor , heat sto rage , and fatigue)usually ass ocia ted with this method of metabolic -rate estimatio n, thr ee unique problemswe re encountered during the Apollo missions : calibrat ion-cur ve inacc urac ies, crew-memb er deconditioning, and the technique used to deter mine hear t ra te . Control of theusual i naccuraci es was not considered feasible because insufficient data were availableduring the EVA; however, a s explained in this re po rt , con trol of the unique sou rc es ofinaccuracy w a s attempted.

Calibration curv es (hea rt rat e compared with metabolic rat e) fo r each individualwere determined before each mission by using standard ergometric calibration tech-niques. Heart -rat e data were obtained under rest ing conditions and at seve ral workra tes ; l eas t - squares ana lys i s w a s used to determine a l inear regression curve.

S tandard e r ro rs as l a rge as 2 1 1 x 10 J/hr (200 Btu/hr) wer e not unusual. Changes intest protocol (mo re data points at various work rates) did not significantly incr eas e theaccu racy , and i t was concluded that this modification to the standard laborat ory ca li-brat ion procedur es w a s not worthwhile.

3

3



Deconditioning of cre wmen between preflight and postflight mea sur eme nts res ult edin a 10- to 35-beats/min inc rea se in hea rt ra te fo r any given workload experiencedbefore deconditioning. Attempts were made to use this information to cor re ct the EVAheart-rate/metabolic-rate curve by shifting (biasing) the curve. Fur the rmor e, toobtain information that would allow inse rti ng bias into the curve (which w a s assumed tobe progress ive with the length of exposure to weightlessness), eff ort s were made toobtain heart-rat e data during succ essiv e in-flight sleep perio ds before the EVA. These

corre ctive eff ort s improved the esti mate s only slightly because a wide variati on inindividual crewmember respo nse contributed greatly to the inac cur aci es inher ent inthis method.

The use of heart rat e alone as an independent indicat or of metabolic r a t es underspace-flight conditions i s not recommended. Er ro rs as l a rge as 80 perce nt have beennoted. However, the us e of hear t ra te a s a dependent method w a s useful when the totalmetabolic expenditure a s meas ured by oxygen and LCG methods could be used as arefer ence. After the fi rs t Apollo flights, u se of the hea rt- rat e method as an indepen-dent real -time method w a s discontinued; the method was then used as a real-time andpostflight dependent method. The relationship between hea rt r at e and metabolic rat ew a s based on hourly mea sur eme nts of the total EVA energy expenditure as determinedby th e oxygen and LCG measurement s. The hea rt- rat e method then allowed real -ti meand postflight measu remen t of specific act ivi tie s on a minute-by-minute bas is. Anexample of the heart-rat e method is the measure ment of metabolic ra te duri ng deploy-ment of the heavy Apollo luna r su rf ac e expe riment s package by the luna r module pilo t.This activity took 2 to 3 minut es to acco mplis h, The respo nse of the oxygen and LCGmethods did not allow isol ation of th is activi ty, but the he ar t- ra te method respondedquickly to this activity and provided the best information on energy expenditure for theactivity .

OXYGENMETHOD

The oxygen method involved using t he PLSS oxygen bottle pr es su re decay toest ima te oxygen consumption and ther eby metabolic rate . The oxygen bottle pr es su rewas telemetered from each EVA crewman and displayed in real time.

Special problems were assoc iate d with using this method as a metabolic-rateindicator. For be st acc ura cy of the oxygen metho d, a measu rement of res pir ato ryquotient (RQ) as well a s oxygen consumption is required. The RQ is a ra ti o of theamount of carb on dioxide produced and the amount of oxygen consumed. Th er e w a s nomeasurement of carbon dioxide production; therefore, the RQ had to be estimated.

A random noise e rr or w a s experienced in the tel emeter ed oxygen bottle pre ss ur edata. To minimize this er ro r, a metabolic computation was not perfo rmed until asignificant drop in bottle pres su re oc curre d. Consequently, at lower metabolic rates,upda tes did not yield information freq uently enough during EVA fo r adeq uate evalu ationof consumab les st at us and cre wmem ber condition.

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The s uit oxygen leakage ra te w a s variabl e and had to be estima ted. The maximumoxygen leakage r at e allowed by the pressure suit specification was equivalent to a meta-

bolic rate of approximately 2 1 1 X 10 J / h r (200 Btu/hr).

Y L L

i .4c =

.-e

t g2 3.3-

; .2

w wL L

1.1y 3

The following attempts we re made to reduce e r r o r s associat ed with the oxygenmethod. Th e RQ was determined on se vera l occasions during crew training and duringmanned tests in the thermal-vacuum facili ties; this determination enabled moreaccurate estimates during missions. A suit-leak check w a s pe rfo rme d at the NASAJohn F. Kennedy Space Cent er be for e launch re adi ne ss to provid e an indication of l eakrates to be expected during the mission. These leak rat es were used a s initial valuesin the oxygen-consumption metabolic program. A pre ssu re integri ty check w a s pe r-formed before each lunar surf ace EVA, and the measure d leak ra te s were used to up-date the program. Experience indicates that the s uit leak will incr eas e during use,especially i f activity is vigorou s. Accordingly, upward adjust ments wer e made in theprogram as the EVA progr ess ed.

-

E

- <E

- 5

LIQUID-COOLED-GARMENT METHOD

8 -

6-

4 -

2 -

Because of the limitatio ns of the oth er methods availa ble to esti mate metabolicrat e, dire ct calorime try was the third method to be considered. A l l the energy pro-duced by metabolism is accountable eithe r as heat produced o r as physical work; directcalorimetry is the mea suremen t of thi s energy production. A complete energy account-ing requ ired measure ment of heat removed by the LCG, h eat (both sensib le and latent)removed by the gas s tre am, heat leak into or out of the pr es su re suit , and energy dis-sipated outside the suit either a s work or as heat fr om frictional work.

The available PLSS data were lim -ited to LCG inlet and outlet temp erat ureand gas inlet temperature and, at first ,app eare d to be inadequate to calcula te anenergy balance. However, the availab il-ity of a thermal model of man in apres sure su i t (ref . 1) together with con-siderable empi rica l data on heat removalf rom man in a pres sure sui t ( ref . 2)allowed est im at es of the types of heatlo ss not directly measured.

An LCG heat -balance compute rprogram was constructed to est imatemetabolic rate. Using the thermoregu-latory model, a relatio nship betweenLCG heat r emov al and metabolic ratefor each LCG inlet temperature (fig. 1)was defined. This estimate of meta-bolic rate was not dependent on propercrew selecti on of inlet temperatu re.The est imat e provided valid data on themetabolic ra te of a crewman who had

5 . 5 r 1 0 r

Lwi -inlet water temperature

I I I I I 15w 1oM) 1SM) 2wO 2500 3aM

Metabolic rate, BtulhrL 1 I J0 527 1054 1581 2108 2635 3162

Metabdic rate, klihr

O L 0'

Figure 1. - Example of factor 1 LCG pro -gram; metabolic rate plotted a s a func-tion of hea t picked up by the LCG foreach of a family of inlet te mpe ra tur es .Relationship is based on the assump-tion that a steady sta te exists; crewmancomfort is not assumed.

5



not selected a comfortable water tempe ratu re (provided h e was in o r near s teadystat e). This estimat e of metabolic rat e, based on inlet tem per atu re and the differen cebetween inlet and outlet tem per atu re, was accu rat e only when the data were r at he rstable. The estimate was not accur ate during a rapid transient of water tempe fatu reo r metabolic rate. To provide data dur ing transient periods, a simp ler esti mate ofmetabolic ra te was used that c onsisted of a line ar equation relating metabolic ra t e toLCG heat rem ova l (fig. 2) . This est ima te was ac cur ate only when comfortab le coolanttempe ratu res were selected by the crewman. A difference in the two esti mates ov er aper iod of t im e indicated that the crewma n was functioning at eit he r a hotter o r coolerbody temperature than optimum. On se ve ra l occasion s, this condition led to the flightsurgeon 's recommendation t o change the LCG div ert er valve setting.

A manual input, identified as "factor, 'I was made availabl e in the pro gra m. Whenthe factor equaled zero , the metabolic r at e w a s based on the esti mate using the differ-ence between inlet and outlet t emp era tur e; when the fac tor equaled 1, the metabolicra te was based on the es tima te using the differ ence between inlet and outlet tem per a-tu re combined with th e abs olut e value of th e inlet tempe rat ur e. An ope rati ona l proc e-du re was developed for c ontr ol of the fac to r input in a consistent manner.w a s chosen af te r obtaining two con sist ent 12-minute read outs . After any tra ns ien t

change, factor zero w a s reselected. Other real -time inputs to the prog ram included theheat l eak into the suit and the LCGflow rate .we re provided by the Mission Evaluation Team be fo re flight and, aft er the Apollo 14mission, during each EVA by means of a telephone link to the medical scie nce suppo rtroom.

Factor 1

These values were based on analysis and

Because of it s analy tica l na tur e, th e LCG method was of no val ue until it could beverified with t est data fr om t rain ing ru ns in the MSC Space Environmental SimulationLaborato ry chamber. The te st da ta indicated that the LCG method predicted the sub-limator water usage and the carbon dioxide absorption in lithium hydroxide canistersas accurately as or mo re accu rately thanthe o the r methods and that th e method

would be of value.

In calcula ting an es tim ate of subl i-mat or water usage, the LCG method w a sof spe cia l value becaus e a heat leak intoo r out of the sui t affected both the LCGmethod and the subl imato r wate r usage.Ther efor e, t he accura cy of the heat-leakest imate w a s not c ritic al fo r estimatingsub lima tor wate r usage, although it wascrit ical for estimating metabolic rate.

Experience with the heat-balanceprogram during early Apollo missionsincr ease d confidence in the progr am andprovided familiarity with its strengthsand weaknes ses. The LCG method pro -vided the best prediction of s ub lim ato rwater usage when predictio ns we re

I I I ..L . L - - _ _ I0 500 1wO 1500 2wO 2500 3Mx1

Metabolic rate, Btuihru-0 527 1054 1581 2108 2635 3162

Metabolic rate kllhr

Figure 2. - Example of factor ze ro LCGprog ram; metabolic rate plotted a s afunction of heat picked up by the LCG.Relationship is based on the assumptionthat the crewman is maintaining a com-fortable LCG inlet temperature.

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compa red with me as ur eme nt s of rema ini ng feedwater. Com par iso ns of LCG andoxygen data indicated that the heat-balance progr am, as designed, compensated fo rinappropriate diverter-valve settings ; however, accuracy w a s reduced if comfortablesetti ngs were not maintained by the crewman. The res pon se of th e heat-balanceprogram w a s demonstrated to be s l o w, which w a s expected, but the progra m didbegin to respond almost immediately to a change in metabolic rate.

INTEGRATI O N OF ME THODS

Because e arl y s tud ies indicated many s our ces of uncert ainty in each method whenuse d individually, the decision was made to use all th re e methods simultaneously. Themetabolic team received all incoming r a w data, processed the data in accordance withthe best real-t ime est ima tes for values of the unmeasurable fac tor s involved, used there sul ts obtained fr om each of the individual methods to provide corre ction fa cto rs forthe ot her methods, and provided one integrated value for the flight surgeon. It wasrealiz ed that this pro cess could be ite rative and that updates could, as the EVA pro-

gr ess ed , cause retrospec tive changes in values. However, a ft er completion of themission and after complete postflight analysis of the data, the results could be com-pa re d with the EVA crewma n's subje ctive evaluation of the workl oads; thus, a betterbas e for planning future lunar tr av er se s could be established.

The res ul ts obtained fro m the Apollo 11 mission were used to plan re st periodsand to establish limits on heart and respir atory ra te s (not only absolute limits but als oli mi ts fo r predicti ons of developing difficulties). These resul ts le d to an extension ofthe lunar surface stay time for the Apollo 1 2 mis sio n without l o ss of confidence. Simi-l a r l y, the experience and information gained fr om preceding mi ssions were incorpor-ated into the planning for the next mission. The confidence level increa sed as theinformation base increas ed; both stay times and useful work on the lunar sur faceincreased, and a high level of confidence was maintained th at s afety had not beenadvers ely affected.

During the actual EVA, the flight surg eon had to be re ady at al l tim es to makerecomm endati ons concerning the advisability of continuing an activity or to aid inplanning a deviation in the mission plan. The princi pal co ncer ns of the flight surgeo nwer e the re ser ve capacity of the crewman and hi s physiological status. The phys-iological status w a s based on a variet y of fact ors , som e of which we re histo ric al(e. g. , the extent of deconditioning resulting fro m 3 days of wei ghtles sness duringtr ans lu na r coast, the amount of fatigue, the preflight physical condition of the cr ew -man, the individual crewman response observed during training for specific activi-ties, the amount and kind of exe rc is e used by the crewman during translunar coast,and the amount and depth of s lee p obtained by the crewman). Other fa ct or s werere al ti me in that they were derived from cur rent activity. Within this context, theflight surgeon required data on both the cumulative and the peak energy demandsbeing expe rie nce d by the crew man during the EVA. Data on cumul ative energy expend-i tu res are mos t direc tly applied in determining the sta tus of consumables and in de te r-mining the general physical sta tus and reserv e. Excessively high hear t ra tes ,hyperventilation, and heat s to rag e can be relat ed to instantaneous peaks of ene rgyexpenditure. The refo re, data that tend to quantitate these peaks a r e evaluated and useda s specifics in the total consideration of crew statu s.

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The integ ration of th e th ree methods h as provided both cumulative and peak data.Use of these d ata during the missi on has prevented the crewmen fro m exceeding pr es etheart-rate and respir atory-rate limits and has assured that physiological limits forheat stor age wer e not exceeded.

Hear t r at es higher than those expected were noted during Apollo EVA peri ods.Because these incr eas es were present during both res t and work periods, i t is thoughtthat they result ed fr om deconditioning experienced duri ng the fi rs t 3 days of transluna rcoas t weightlessness. These higher hear t ra te s have been carefully included in allconside rations . With mor e understanding of the biomedical effects of both weightless-ne ss and lunar sur face exposure, techniques may be developed to minimize the unde-sir abl e changes.

RESULTSAND ANALYSI S

Because of th e problems experienced in using each of th e thr ee a sse ssm entmethods, the real -ti me values repo rte d to the flight surgeon and the PLSS consumabl esanalysts were integrated values. When determining an ass ess ed metabolic rate, th eteam leader examined the res ult s of all three methods together with al l other PLSStelemetry data. After the flight, this integrated resu lt w a s furt her updated by compar-ing the resu lts of actual sublimator water supply measur emen ts, water tank warning

1

tones,maximum (assuming suit oxygen leakage w a s zero ). Actual sublima tor wate r supplymeasurements, which were made by the crewmen immediately after the EVA, andwatertank warning tones supplied a maximum limit to the integrated r esu lt s. A l l e r r o r s(such as water spillage) decreased the measured water remaining, increasi ng theapparent metabolic rate . Total oxygen used als o provided an upper l imit to the averagemetabolic ra te (assumin g suit oxygen leakage was zer o). Lithium hydroxide analys is,performed on th e Apollo 9 cani ster , provided a basis for determining carbon dioxide pro-duction, thus an assessment of RQ, which w a s then used to re fine the oxygen-methodand LCG-method res ult s. The postflight integrat ed metabolic re su lt s fo r the ApolloProgr am extravehicular activities ar e shown in table I. The overall e rr or of integratedmetabolic assessments made during the Apollo flights was estimated to be 10 to 15 per-cent, based on method variability.

PLSS lithium hydroxide cani ster anal ysis (Apollo 9 only), and oxygen-method

On the Apollo 15 to 17 missions, which had auxilia ry sublimator water tanks,a warning tone sounded when the main tank w a s depleted.

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TABLE I. - METABOLIC EXPENDITURES FOR APOLLO LUNAR SURFACE EVA

CD RLMP

CDRLMP

Apollomission

111

k J / h r B t u h r k J / h r B tu /h r kJ /h r B t u h r k J h r B t u h r k J/ hr Btu/hr

818 775 1023 969 899 851 - - _ _ 949 900

864 818 1017 963 1232 1167 -- _ _ 1028 975

1267 1200 1471 1393 1269 1202 -- - - 1267 1200 2'43

1006 953 1028 974 1119 1060 - - __ 1054 1000 3'90

1 1

12

17

EVA

1-2

1

3

1-3

1--Mean

Metabolic rate

Geological Lun ar rovingstation Overhead vehicleactivity operat ions act ivi t ies I

Crewman ALSEPdeployment( 4

913 865 902 854 922 875DR _ _LMP

1 1 I- -

I1058

I1002 I 1038

1983

1 1: I 1: I1054

11000

I3.78

CDR 1095 1037 1013 959 1303 1234 578 547 1086 1030LMP 1 962 1 911 I 788 I 746 I 981 I 929 I 447 I 423 I 854 I 810 I 4.83

CDR 869 823 905 857 1146 1085 725 687 917 870LMP 1081 1024 1125 1065 1154 1093 666 631 1065 1010

CDR _ _ - - 933 884 1044 989 470 445 822LMP _ _ _ _ 11023 1 969 1 987 I 935 1 438 I 415 1 874 1 % I 7'38

Tota l t ime . h r I 28.18 1 52.47 I 52.83 1 25.28 I 158.76 I

aCDR = commander, LMP = lunar module pilot.

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CONCLUDING REMARKS

The following conclusions a r e based on Apollo Pr og ra m metabolic expendituremeasur ement estimations . The thr ee methods of metabolic ass ess men t, u sed withknowledge of their defici encies , proved to be valuable ind icat ors of crewman metabolicproduction. The over all aver age metabolic production of Apollo crewmen during extra-

3 3vehicular activity on the lunar sur face ranged fro m 823 X.10 to 1267 X 10 J/hr ( 7 8 0 to1200 Btu/hr).

Lyndon B. Johnson Space Ce nt erNational Aeronautics and Space Administration

Houston, Texas, September 25, 1974914-50-95-13-72

REFERENCES

1. Stolwijk, J . A . J. : A Mathematical Model of Physiological Te mpe ra tur e Regula-tion in Man. NASA CR-1855, 1971.

2 . Waligora, James M. ; and Michel, Edward L. : Application of Conductive Coolingfo r Working Men in a Thermally Isolated Environment. Aerospace Med., vol. 39 ,no. 5 , M ay 1968 , pp. 485-487.

10 NASA-Langley, 1975 s- 39 4



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