Atmosphere Control of a Mars GreenhouseMars Deployable GreenhouseMars EnvironmentPlant Growth RequirementsPlant Growth RequirementsEnvironmental ParametersAtmosphere Separation TechnologiesTrace Contaminant Control TechnologiesSelection of Atmosphere Control TechnologySelection of TCC TechnologyReferencesQuestions?Atmosphere Control of a Mars Atmosphere Control of a Mars GreenhouseGreenhouseColleen HigginsColleen HigginsASEN 5519ASEN 5519December 9, 2003December 9, 2003Mars Deployable GreenhouseMars Deployable GreenhouseNASA Design NASA Design Competition Competition ––MarsPortMarsPort2001 2001 ––2002 School Year2002 School Year8 Team members, 8 Team members, including PhD studentincluding PhD studentSupport human Support human exploration on Marsexploration on MarsMars EnvironmentMars EnvironmentAverage temperature Average temperature range: 186 range: 186 ––268 K268 K--8787°°C C ----55°°CCAvg. pressure: 6 Avg. pressure: 6 mbarsmbarsEarth ~ 1013.25 Earth ~ 1013.25 mbarsmbarsDay: 24.66 hoursDay: 24.66 hoursSurface gravity: Surface gravity: 3.69 m/s3.69 m/s22Surface density: Surface density: 0.02 kg/m0.02 kg/m33Earth ~ 1.217 kg/mEarth ~ 1.217 kg/m3Percent Percent AbundanceAbundanceAtmospheric Atmospheric ConstituentsConstituents0.030.03Water (HWater (H22O)O)0.070.07Carbon Carbon Monoxide (CO)Monoxide (CO)0.130.13Oxygen (OOxygen (O22))1.61.6Argon (Argon (ArAr))2.72.7Nitrogen (N)Nitrogen (N)95.3295.32Carbon Dioxide Carbon Dioxide (CO(CO22))3(Owen, 1992) (Kieffer et al., 1992)Plant Growth RequirementsPlant Growth Requirements10x10x5 cm10x10x5 cm30x30x30 cm30x30x30 cm5x5x15 cm5x5x15 cm15x15x15 cm15x15x15 cmVolume of Volume of Root ZoneRoot ZoneEthyleneEthyleneEthyleneEthyleneTBDTBDEthylene/Ethylene/Gaseous Gaseous AmmoniaAmmoniaContamination Contamination ControlControl~ 90~ 9050 50 --757550 50 --707050 50 --8585Humidity Humidity (%(%RhRh))20 20 --282820 20 --282815 15 --252522 22 --2828Temperature Temperature ((°°C)C)12 12 --18181818181818 18 --2424Photoperiod Photoperiod (hr)(hr)0 0 --AmbientAmbient300 300 --400400275 275 --400400250 250 --275275Light Light ((µµmol/mmol/m22g)g)SproutSprout(bean, alfalfa)(bean, alfalfa)FruitFruit(tomato, (tomato, pepper)pepper)RootRoot(onion, carrot)(onion, carrot)VegetativeVegetative(leaf, lettuce)(leaf, lettuce)(Eckart, 1996)Plant Growth RequirementsPlant Growth RequirementsEquation of Equation of Photosynthesis Photosynthesis 6CO6CO22+ 6H+ 6H22O + light O + light →→CC66HH1212OO66+ 6O+ 6O22Need ONeed O22during night during night to burn carbohydrates to burn carbohydrates stored in their rootsstored in their rootsMinimum of 5 kPa for Minimum of 5 kPa for healthy plant growthhealthy plant growth(Wheeler et al., 1996)Courtesy of thinkquest.orgEnvironmental ParametersEnvironmental ParametersEnvironment ControlsEnvironment ControlsVentilationVentilationTemperature ControlTemperature ControlGas CompositionGas CompositionRelative HumidityRelative HumidityAtmospheric ManagementAtmospheric ManagementSeparation/Storage of OSeparation/Storage of O22Restoring consumed CORestoring consumed CO22Conserving, restoring and Conserving, restoring and recycling Hrecycling H22OO< 50ppb< 50ppb(at 100 kPa)(at 100 kPa)Ethylene GasEthylene GasOptionalOptionalInert Gas Inert Gas CompositionComposition> 5 kPa> 5 kPaOO22Partial Partial PressurePressure0.1 0.1 ––3 kPa3 kPaCOCO22Partial Partial PressurePressure40 40 ––90%90%Relative Relative HumidityHumidity10 10 ––30 30 °°CCTemperatureTemperatureMarsPort Design ParametersAtmosphere Separation TechnologiesAtmosphere Separation TechnologiesCOCO22frozen from atmosphere when in contact with surface frozen from atmosphere when in contact with surface below its deposition temperaturebelow its deposition temperaturedoes not accomplish Odoes not accomplish O22separation due to the presence of a separation due to the presence of a buffer gas such as nitrogenbuffer gas such as nitrogenFreeze OutFreeze Outreacting organic molecule and oxygen releases Hreacting organic molecule and oxygen releases H22O and COO and CO22does not recover Odoes not recover O22produced by photosynthesisproduced by photosynthesisOxidationOxidationcryogenic air separated based on boiling pointscryogenic air separated based on boiling pointsprocess uses large amounts of energy to cool air to a liquid process uses large amounts of energy to cool air to a liquid statestateDistillationDistillationseparate gases by allowing certain molecules to pass more separate gases by allowing certain molecules to pass more freely than othersfreely than othersmolecules that are polar (COmolecules that are polar (CO22) easier to separate) easier to separateMembraneMembraneminerals with ability to absorb different gases based on the minerals with ability to absorb different gases based on the crystalline structure of the mineralcrystalline structure of the mineralchanging the size of spacing within structure will allow changing the size of spacing within structure will allow different molecular sizes to fit insidedifferent molecular sizes to fit insideZeolitesZeolitesTrace Contaminant Control Trace Contaminant Control TechnologiesTechnologiesorganic compounds broken down into Horganic compounds broken down into H22O, COO, CO22and Nand N22catalysts are available to accelerate oxidation processcatalysts are available to accelerate oxidation processozone is most effective catalyst, but can also cause ozone is most effective catalyst, but can also cause destruction of human and plant tissuesdestruction of human and plant tissuesTiOTiO22absorbs light in UV spectrum, creates ionic potentials at absorbs light in UV spectrum, creates ionic potentials at surface of the catalyst that oxidize contaminants at low temps. surface of the catalyst that oxidize contaminants at low temps. ((BaskaranBaskaranet al., 1998)et al., 1998)OxidationOxidationreducing a gas to a liquid and passing it near a cold plate to reducing a gas to a liquid and passing it near a cold plate to separate out volatile compounds, contaminants not destroyedseparate out volatile compounds, contaminants not destroyedEthylene liquefies at 169.4 K, COEthylene liquefies at 169.4 K, CO22at 194.7 K at 194.7 K ––COCO22would would also be