Adv. SpaceRes.Vol. 12, No. 5,pp. (5)211—(5)217,1992 0273—1177/92$15.00Printed in GreatBritain. All rightsresa~ved. Copyright© 1991 COSPAR

BIOSPHERE2: A PROTOTYPEPROJECTFORAPERMANENTAND EVOLVING LIFE SYSTEMFORMARS BASE

MarkNelson,*JohnP. Allen** andWilliam F. Dempster**

~ ofEcotechnics,LondonWC1, U.K**SpaceBiospheresVentures,Oracle,Arizona85623,U.S.A.

ABSTRACT

As partof the ground-basedpreparationfor creatinglong-termlife systemsneededfor spacehabitationandsettlement,SpaceBiospheresVentures(SBV) is undertakingtheBiosphere2 projectnearOracle,Arizona.Biosphere2,currentlyunderconstruction,isscheduledtocommenceits operationsin 1991witha two-yearclosureperiodwith a crewof eightpeople.Biosphere2 is a facility which will beessentiallymaterially-closedto exchangewith theoutsideenvironment.It is opento information andenergyflow.Biosphere2 is designedto achievea complexlife-supportsystemby the integrationof sevenareasor“biomes”— rainforest,savannah,desert,marsh,ocean,intensiveagricultureandhumanhabitat.Uniquebioregenerativetechnologies,such as soil bed reactorsfor air purification, aquaticwasteprocessingsystems,real-time analyticsystemsandcomplexcomputermonitoringandcontrol systemsare beingdevelopedfor theBiosphere2 project.Its operationshouldaffordvaluableinsight intothefunctioningofcomplex life systemsnecessaryfor long-term habitation in space.It will serve as an experimentalground-basedprototypeandtestbedfor the stable,permanentlife systemsneededfor humanexplorationof Mars.

BIOSPHERE2 PROJECT

TheNASA Reporton the90-DayStudyon HumanExplorationof theMoonandMarsidentifiedasperhapsthebiggestchallengeinmeetinghumanneedsin spacetobe“thedevelopmentof regenerativelife supportsystems,which could eventuallyprovide food aswell asrecyclewastes,with a subsequentreductioninthe quantity of suppliesthat mustbe transportedfrom Earth”. It noted that “life support systemsforexploration...musthavecapabilitiesfor airrevitalization,waterpurification, foodsupply,wasteprocess-ing, environmentalmonitoringandcontaminationcontrol,thermalandhumidity controlandfire suppres-sion” /1/.

Yet despitethis recognitionof theneedfor suchregenerativesystemsit remainsall tootrue,asthe90DayStudynotes,that“little isknownabouttheoperationalcharacteristicsandrisksassociatedwith long-termoperationof regenerativelife supportsystems,which havenotbeentestedon humansinsituationscloselysimulatingthespaceenvironment.”

The goal of theBiosphere2 project is to createthe first indefinitely operatingbioregenerativesystemcapableof full humanlife support,a prototypeof the type of facility which caneventuallyserve aspermanentspacehabitation— andto closelymonitorandmanageits operation.

Biosphere2 is designedas a mini-biosphericsystem.It will be essentiallymaterially isolatedfrom itssurroundingsby askinof spaceframeanddoublelaminatedglasspanelsaboveground;andby a stainlesssteelliner belowgroundwhich createsa completeair- andwater-tightenvelope.Energeticallyit is opento bothsunlight (an averageof 65 percentof photosyntheticactiveradiationpassesthroughthe glassstructure)andenergyproducedfor the operationof its heating,cooling, andothermechanicalsystems(Table 1). Informationallyit is alsoopen,communicatingviacomputer,telephone,andvideolinks.

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TABLE 1. Energyof Biosphere2

Electrical Peak Demands KilowattsBiosphere 2 Airtight Enclosure 1500Energy Center 1500

TOTAL 3000Generating Capacity* 3750

(S Fossil Fueled Generators)

Cooling Peak Demands Refrigeration (Tons) Kilojoule / HourIntensive Agriculture 900 11,395,000Wilderness 1900 24,056,000

TOTAL 2800 35,451,000

Heating Peak Demands BTU / Hour Kilojoule / HourIntensive Agriculture 3,400,000 3,587,000Wilderness 7,000,000 7,385,000

TOTAL 10,400,000 10,972,000

Solar Energy Entering Glass5 BTU / Hour Kilojoule / Hour KilowattsIntensive Agriculture 8,200,000 8,651,000 2,403Wilderness 17,500,000 1,462,000 5,129

TOTAL 25,700,000 27,113,000 7,532(5Peak)

TABLE 2. Areas of Biosphere2

Areas Square Feet Square Meters Square Acres HectareGlass Surface 170,000 15,794 3.90 1.58

FootprintsIntensive Agriculture 24,020 2,232 .55 .22Habitat 11,592 1,077 .27 .11Rainforest 20,449 1,900 .47 .19Savannah/ocean 27,500 2,555 .63 .26Desert 14,641 1,360 .34 .14West Lung (airtight portion) 19,607 1,822 .45 .18South Lung (airtight portion) 19.607 1.822 .45 .18

TOTALAIRTIGHT FOOTPRINT ....137,416 12,766 3.15 1.28

Energy Center 30,000 2,787 .69 .28West Lung (weathercover dome) 25,447 2,364 .58 .24South Lung (weathercover dome) 25,447 2,364 .58 .24

Ocean Water Surface Area 7,345 682 .17 .07Marsh Surface Area 4,303 400 .10 .04

TABLE 3. Volumesof Biosphere2

Volumes Cubic Feet Cubic MetersIntensive Agriculture 1,336,012 37,832Habitat 377,055 10,677Rainforest 1,225,053 34,690Savannah/Ocean 1,718,672 48,668Desert 778,399 22,042Lungs (at maximum) 1,770,546 50,137

TOTAL 7,205,737 204,045

Soil, Water, Structure, Biomass 671,635 19,019Air 6,534,102 185,026Ocean Water (1,000,000 gallons, approx) 133,690 3,786Fresh Water (200,000 gallons, approx) 26,738 757

Biosphere 2: Prototypefor PermanentSpace Habitation (5)213

I

Figure 1. Biosphere 2 longitudinal section showing wilderness biomes, right to left: rainforest, savannah (at top ofrock cliffs)marine and marsh (at base of rock cliffs), and desert. This longitudinal section measures539 feet.

Thelife systemsof Biosphere2 aredesignedasan interplayof sevenbiomicareas:humanhabitat,intensiveagriculture,rainforest,savannah,desert,marshandocean(Figurel). Theairtight footprint of Biosphere2 is about12,700squaremeters(Table 2). This figure includesthe two variablevolume “lungs” whichallow equilibrationof volume expansionsandcontractionscausedby differencesin temperatureandbarometricpressurebetweenBiosphere2 andtheoutsideenvironment.Thetotalvolumeis about200,000cubicmeters(Table3).

Thermalcontrol is avital functionfor themaintenanceof necessaryenvironmentalconditionsfor the lifesystems.Biosphere2 isdesignedto useairhandlingunitswith hot,chilled andevaporativelycooledwatercoils which do not violate closurerequirements.The air handlerswhich are distributedthroughoutthestructurehaveacombinedcapacityof about1.2million cubicfeetperminute/2/. The ability to providedifferential cooling/heatingin varying areasof the facility permit the biomic areasto havesomewhatdifferent“climates”,althoughthe entireregimeis tropical(Table4).

Designedfor aprojectlifetimeof 100years,Biosphere2 will bemanagedby an insidecrewof eightpeoplewho will be fully sustainedby its operationfor air and water recycling, food productionandwasteprocessing.A numberof innovative technologiesbeing developedfor the Biosphere2 project havepotential for increasingbioregenerativelife supportcapability, necessaryfor the SpaceExplorationInitiative includingMarsexplorationandhabitation.

TABLE 4. Temperature Ranges of Biosphere 2 TABLES. ProjectedAtmosphericComponents of Biosphere 2(Extremes Allowed)

Low PRESSURE TotalMassCelsius Fahr Celsius Fahr MM.HG PSI KPA KiIogram~

Rainforest 35 95 13 55Savannah 38 100 13 55 Oxygen 136.1 2.63 18.13 31800Desert 43 110 2 35 Nitrogen 507.6 9.82 67.67 103775Intensive Agriculture 30 85 13 55 Carbon Dioxide .21 .004 .028 67

Water Vapor 13.4 .26 1.79 1761Argon 6.1 .12 .83 1782NOTE: Pressures do not total to standard 760 mm hg or 14.7 psibecause at 3900 feet elevation, atmospheric pressure is only about663 mm hg (12.8 p~i).

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Agricultural System

Intensiveagriculturalsystemshavebeenunderdevelopmentsincethe projectcommencementin 1984.Somefifty major cropvarietiesare utilized andare designedto supportthe eight crew with a balanceddiet includingmeat,fish, eggsandmilk throughtheraisingof African pygmygoats,pygmyswine,tropicalfowl andTilapia fish. Becauseof the smallwaterandair buffersof Biosphere2, agriculturalsystemsthatdo notusechemicalpesticidesorherbicideshavebeendevelopedfor theproject.Closeintercroppingandrotationof cropsaredesignedto maximizeyieldswithin thelimitationsof light levelsprovidedby ambientsunlight.Processingof inediblebiomassand animal wastesandtheir returnto the agriculturalsoilsaredesignedto testif high levelsof soil fertility canbemaintainedoverthe intended100yearlife of Biosphere2.

Soil BedReactors

The agriculturalareaservesa dual functionbecauseof theuseof “soil bedreactors”(SBR)asa meansofair purification as well as biomassproduction. SBRs do not require expendablematerialsor muchmaintenance,and relying on biological processeswould appearto be morereliableand less subjecttocatastrophicfailure than alternativetechnologies/3/. They havebeen usedsuccessfullyto controlmalodorousgasemissionsby industriesin EuropeandNorth America /4,5/. Literaturesearchesrevealextensivereferencescitingevidencethata widevarietyof contaminantgasesmaybemetabolizedby soil.Indeed,it is the diversity of microbial function coupledwith their rapidgenerationtime that providesastrongreasonforutilizing this “natural”mechanismas asafeguardfor anticipatedandunanticipatedtracegasbuildupsfor spacemissionsandbases.

For spaceapplicationsin bioregenerativesystems,the use of lunar regolith as a componentin theirsubstrate,suitably amendedto improve fertility, will decreasetheir weight/volumecosts.Long-termimpactof removalof atmosphericcontaminantson the soil is not known thoughSBRshavebeeninoperationfor long periodsof time in Europe.TheseSBRshaveonly requiredperiodicwateringduringdry periodsand occasionaluseof compostas a carbonsourcefor themicrobialcommunitiesof thesoil.Continueddevelopmentof detailedsoil nutrient cycling modelsare neededaswell as increasedexperi-mentalwork/6/. DetailedresearchconductedforSpaceBiospheresVenturesin 72 replicateSBRsystemsfor over a year indicatedthat continuedhigh level of crop productivity andsoil fertility was possiblesimultaneouslywith the air purificationfunction/7/.

In the humanclosuresthatSBV conductedin September1988,MarchandNovember1989(closuresof3, 5 and 21 daysrespectively)in the Biosphere2 TestModule, an SBR that servedas the primary foodbiomassproducerwas included along with a numberof other life systems,including aquaticwastetreatmentchambers,and avariety of otherplantsin soil containers.Therewasno appreciablebuildupofanyof themajortracegases(measuredby continuoussensors)norof anyothergasesas revealedby gaschromatographymassspectrometry(GCMS)analysis/8,9/. The entiresoil of the intensiveagricultureareaof Biosphere2 will functionasa soil bedreactor.If needed,theentireatmosphereof the facility canbe pumpedthroughthis soil in less than a day.Becauseof therelatively smallbuffer containedin theBiosphere2 atmosphere(Table 5), and the consequentrapidcycling timesof components,the effectivemanagementof air qualityandpreventionof tracegasbuildupareof primaryimportance.

AquaticWasteProcessingSystems

Anotherpromisingtechnologythat SBV is advancingare aquaticwasteprocessingsystems.Wastesofimportanceto spacebioregenerativesystemsincludehumansolid andliquid waste,graykitchenwater,andavarietyof potential volatile technogenicgasesfrom the materialsof the enclosedspacehabitat.Yetvery little technologydevelopmentfor bioregenerativesystemshasoccurredto dateandmany of thetechnologiesproposedinvolve extremeenergycostsand technologicalmaintenance.As SchwartzkopfandCullingford note in a recentpaper:“Many previousCELSS(closedecologicallife support system)conceptshaveincorporatedhigh energymethodsof wastedegradationsuchas wet oxidationor super

Biosphere2: Prototypefor PermanentSpace Habitation (5)215

critical wet oxidation. In theprocess,all of theenergystoredin the chemicalbondsof thewastematerialsis lost. By usingeitherbioregenerativetechnologiesor appropriatephysiochemicaltechnologies...someof the chemical bond energycanbe providedto the systemby convertingwastesinto low complexitymaterialswhich canbe usedas foodstocksfor bacteria,algaeor higherplants”/10/.

The creationof aquaticsystemssometimescalled“marshwasteprocessingsystems”utilizes the naturalability of aquaticplant/microbialassociationsto perform thewasteprocessing,metabolizingor concen-tratingpotentialpollutants,while atthe sametimeproducingvaluablebiomassgrowth.The high rateofproductivity/transpirationof theseaquaticplantsalso makethem usefulas sourcesof purifiedwater inbioregenerativesystemaftercondensingthe moistureevapotranspiredthroughplant leaves.

AquaticSystemsIn IntegratedBioregenerativeTestbeds

SpaceBiospheresVentureshastakentheleadinapplyingaquaticwasteprocessingsystemstooperationalbioregenerativelife supportsystems.During 1987 SBV with consultationfrom B.C. Wolverton,of theNASA StennisCenter,developeda miniaturizedmarshsystemfor processingof humansolid andliquidwastesalongwith kitchengraywaterin the Biosphere2 TestModule.Thissystemsupportsa variety ofaquaticplants,includingwaterhyacinthandcanna.Effluent from this marshsystemwasmonitoredandthencycled into the irrigation watersystem.This systemwasutilized during all the SBV humanclosureexperimentsduring which time onepersonlived in the Test Module utilizing a bath room andkitchenfacilities connectedto themarshsystem.No odorproblemsfrom themarshsystemswerereportedduringanyof theseexperiments(Figures1,2).

Similar aquaticwasteprocessingsystemstotheoneusedin theBiosphere2 TestModulewill beemployedin Biosphere2 for human wasteandgray water regenerationfor its human crew of eight. BecauseBiosphere2 is designedfor alonglife andwill becloselymonitoredanalyticallyto studyits operation,itis expectedthat valuableinformation abouttheoperationof suchmarshsystemsinclosedbioregenerativesystemswill be thusgained:theirmaintenanceneeds,reliability andperformanceover time.

Artificial IntelligenceSystemsFor ControlAnd Management

SpaceBiospheresVentureshasdesignedandis implementinga5-levelhierarchyapproachto developinga“NerveSystem”forClosedBioregenerativeLife SupportSystems.Thefive functionallevelsare1) point

Nflc.(e 0,010/fl WflfltO NocycW5 Syc Ph,.pSok.NeF. ~ 00.1. R.,y,lng Sy

JO-Oct 20-Oct 09-Nov J9-No~ 20—Nov 19—Oct 29—Oct 09—N.o 19—No, 29—Nov

-1009 Nc,.,nb — 1999

Figure 2. Nitrate and phosphate levels in the aquatic plant waste processing system in Biosphere 2 Test Module during the 21day human closure. The researcher entered a previously seated and functioning system on 2 November, 1989. Rises in nitrateconcentration coincide with the input of batches. Growth of plants and symbiotic microbes then reduced levels, until the nextbatch release. Note how after last batch was introduced (21 November) and human exited system 23 November, levels werepulled down to below 2 PPM, lower than they were before entrance of human and start of waste processing.

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sensingandactivation,2) localdataacquisitionandcontrol,3)systemsupervisorymonitoringandcontrol4) global monitoringandhistoricalarchiveand,5) telecommunications.

Thebackboneof theNerveSystemisaBroadbandNetworkthatcommunicatesdifferentlevelsandpermitsDistributedProcessesto beindependentof otherpeerprocesseswhennecessary.Also, this allows useofdiversecomputeroperatingsystemssuchas PC’s,UNIX, Macintosh,etc. or audio/videosignalsthatotherwisewould be incompatible.In addition, to preparefor Biosphere2 operationsuniquecomputersoftwarehasbeendevelopedfor thefollowing areas:

AtmosphericCarbon Dioxide Modelingand Real-TimeMonitoring of BioregenerativeLife SupportSystems.Work is continuingon a dynamicmodel which simulatesandpredictsC02levels which canincludereal-timeandhistorical datain its calculations.Themodel hasbeenusedto simulateandpredict

C02 levels for Human in ClosedEcosystemexperimentationin the SBV Test Module andwill beemployedfor Biosphere2 operations.

ThermodynamicModeling.Simulation(BIOSYS)andReal-TimeControlin BioregenerativeLifeSuDDortSystems.Materially closedregenerativelife systemsareopenfor informationandenergyexchangeto theouterenvironment.Energyinputsfor photosynthesis,electricalpower,communications,andheatingarerequired.Asaresultantof energeticpermeabilitythereis aneedto offsetexternalfluctuationsanddisposeof wasteheat.

Internalrelativehumidity andenergyefficiencymustalsobemanaged.Machineryforheatingandcoolingair tendsto be complexenoughto typically require a dedicatedhuman stafffor operations,monitoringand maintenance.SBV has developedBIOSYS (a ThermodynamicSimulation Model For ClosedBioregenerativeLife SupportSystems)andReal-TimeExpertSystemApplicationstointegratesimulationandcontrolof internalclimate.

Global Monitoring of ClosedBioregenerativeLife SupportSystems.Bioregenerativeprocessesarenon-linearand thereforemany biological,technicalandhumanfactorsplay key rolesin systemstabilityanddynamics.Thequantity,immediacyandcomplexityof thesefactorshasledSBVtodevelopautomatedmonitoringanddiagnosisof overallsystemstatus.Also, ahistoricalarchiverelationaldatabasecombinesdiversedatasets:environmental,analyticalandbiological (this last set from the SBV BioaccessionsDatabasewhich inventoriesand keepsa historyof all biological introductions).Atmosphericandwaterquality neednotonly to bemonitoredfor realtime levelsbutalso for trendsandexpectedbehavior.TheGlobalMonitorandAdvisor alsoservesasa repositoryinwhich modelsof bioregenerativeandtechnicalprocessescanbe testedin real- time simulations.

Nutrition Diet PlanningandCropProductionScheduling.Within a closedecologicalsystem,spaceandfacilities for providingadequatenutrientsfor humansis limited.The daily human diet should includecalories,protein,fats, andcarbohydratesdeemedoptimalor sufficient. Also, 28 or so essentialaminoacids,vitaminsandmineralsshouldachieveRecommendedDaily Allowanceor“safeandadequate”levelsin thediet. Theaim of thesystemis to providea schedulefor plantingcropssothat eachharvestyieldsanappropriatequantityandcombinationof foodsfor optimaldaily nutrition.Thisrequiresthenutritionalvalues,quantityandtimetableof cropproduction.

The “nerve system”being developedfor theBiosphere2 project is uniquein the field asit canbe usedforsimulationsandthencheckedagainstthe resultsinactualoperatingbioregenerativesystems.Thiswasfirst appliedto TestModule experimentsandwill bealsotrueforBiosphere2 which will haveover2,000internalsensors.

CONCLUSION

The operationof Biosphere2 shouldprovidea wealthof information aboutthe operationof complexbioregenerativelife supportsystemsoverlong periodsof time.The constructionand life systemswere

Biosphere 2: Prototype for Permanent Space Habitation (5)217

designedfor a project lifetime of 100 years,althoughthe first “mission” will be a two yearclosureexperimentwith eight residentresearchersthat will commencein 1991.

Neverbeforehavesuchcompletecroppingareas/bufferingvolumesof air, waterandsoil beenmatedtotechnical/engineeringsystemsof environmentalcontrol andsupport.In additionto insightsBiosphere2mayyield ontheoperationof naturalecosystemsandglobal biosphericsystems,it will functionasauniquetestbedfor space— wherecrewswill operateboth bioregenerativelife support systemsandtechnicalones.Learningto integrateand harmonizeboth life systemsand technical onesandobservingtheirbehaviorduringperturbationsovertimewill bean importantmilestonein beingabletopredictthebehaviorof createdhabitats(“eco-syntheses”)for space.It shouldalso projecta powerful vision for permanentspacehabitation,wherethevital ecologicallife sustainingfunctionsof ourglobal biospherewill havetoberecreatedin miniature,andsustainedrobustlyforcrewwell-being.It may alsoincreasethewell-beingandproductivity of spacecrewsto inhabit amicro-biospherewith boththe increasedsafetyaffordedbyredundancyof function,both at the biological andtechnicallevels and the familiarity andsatisfactionprovidedby a diversityof ecosystems.

REFERENCES

1.A. Cohen,Reportof the90-DayStudyon HumanExplorationInitiative,AdvanceCopy,NASA,(1989).

2. W.F. Dempster,Biosphere2: TechnicalOverview of a Manned ClosedEcological System,19thIntersocietyConferenceon EnvironmentalSystems,San Diego,CA. July, SAETechnicalPaperSeries,No. 891599,(1989).

3. H.L. Bohn andR.K. Bohn, Soil bed scrubbingof Fugitive GasReleases,J. Environ. Sci. HealthA21:561-569,(1986).

4.. D.A. CarlsonandC.P.Leiser,Soil Bedsfor theControlof SewageOdors,J.WPCF38:829-840,(1966).

5. H.L. Bohn,Soil Adsorptionof Air Pollutants.J. Envir.Quality, 1:372-377,(1972).

6. H.L. Bohn,Soil andCompostFiltersof MalodorantGases,APCA25:953-955,(1975).

7. R. Frye and C. Hodges,Soil Bed ReactorWork of the EnvironmentalResearchLaboratoryof theUniversityof Arizona in Supportof theResearchand Developmentof Biosphere2, 33-44in BiologicalLife SupportSystems,ed. by M. Nelson and G. Soffen,SynergeticPress,Oracle,AZ, and in NTISpublicationNASA CP-3094,(1990).

8. M. Nelson,The Biotechnologyof SpaceBiospheresin Fundamentalsof SpaceBiology, ed.by G.Malacinski,JapanScientificPress,SpringerVerlag,(1990).

9.A. AIling, L. Leigh, T. MacCallumandN. Alvarez-Romo,Biosphere2 Test ModuleExperimentationProgram,23-32 in BiologicalLife SupportSystems,ed. by M. Nelsonand G. Soffen,SynergeticPress,Oracle,AZ andin N1’IS publicationNASA CP-3094,(1990).

10. S. Schwartzkopfand H. Cullingford, ConceptualDesignfor a Lunar-BaseCELSSin Engineering,ConstructionandOperationsinSpaceII, Proceedingsof Space90,ed.S.JohnsonandJ.Wetzel,AmericanSocietyof Civil Engineers,(1990).