10:45 〜 12:15
[MIS21-P09] Is the regolith suitable for martian agriculture? Potential utility of vesiculated regolith
キーワード：土中微生物、発泡体、火星の爆発的噴火
In the movie “Odessey” the main character, who was left alone on Mars during the exploration grew potatoes for survival. On Mars soils suitable for growing crops do not exist so that some ideas are necessary to transform the surface materials such as regolith to soil. In the scope of long-term residence on planetary surface such as Moon and Mars, autonomous food production and crop cultivation have been investigated. Several ideas are already proposed and these studies are categorized as space agriculture( Souza, D. 2020. “Agriculture in Mars: Habitat Marte Findings.” ,Yamashita et al 2009,On-site resource availability for space agriculture on Mars ). As for the characteristics of soils to promote growth of crops, following factors have been proposed; contents and species of organics for nutrition, amount and storage/transport capacity of water, chemical composition of water in equilibrium with minerals and pH and etc. But gross pictures have not yet been clarified. In this study a slightly different approach is adopted to evaluate ability of surface materials as crop-growing soil. The criterion of "fertility;ability to promote crop growth" is evaluated by the activity of soil microorganisms in terms of CO2 emission. We find highly vesiculated pyroclastic materials have high potentiality for this purpose.
On the surface of Mars fine granular materials such as regolith and dust are widely distributed. The starting question in this presentation is "Is the martian regolith suitable for martian agriculture?" What kind of regolith materials is suitable?, If identified where to obtain? To answer these questions we have conducted a series of simple experiments to evaluate "fertility" of regolith-analog materials.
We used a commercial small CO2 sensor with WiFi/Bluetooth communication ability ( RATOC Systems Inc., ). The sample is mixture of analog of surface regolith and mulch( 2:1,3:1 in wight ratio). They are put into a sealed plastic case and monitor CO2 concentration at 1min. Interval. Tested analog of the regolith is vesiculated ones: Kawagodaira pyroclastic flow deposit, Hachinohe pyroclastic flow deposit, Kanumatuchi (pyroclastic fall deposit of Akagi volcano), Chuseri pyroclastic fall deposit at Towada and non-vesiculated ones: glass sand (commercial name:Zariganinosuna) and glass beads of 0.5mm. In the first several hours all the samples exhibit similar increase in CO2 concentration. In the long term observation quite different behaviors are observed. In Kawagodaira PFlow deposit high concentration about 4000ppm has been maintaied while in Zariganisnosuna
after reaching the maximum the concentration is gradually decreasing in the time scale of several days. This behavior is same as the case of glass beads. Other vesiculated samples exhibit similar behavior except for Kanumatuchi. In vesiculated samples microorganisms could survive and grow while non-vesiculated samples the activity of microorganisms is inhibited. The existence of micropores seems to be a controlling factor. We can conclude vesiculated microporous materials are good candidates for fertile soil. The importance of micropores in the activity of microorganisms has been already pointed out by Or et al(2007) and we could confirm their arguments.
Availability of vesiculated materials on Mars: Several investigations have clarified recent activities of explosive eruptions on Mars by using high resolution imagery. Around these vents in Cerberus Fossae(Moitra et al EPSL 567(2021) )and Arabia Tera(Bates et al Icarus 390 (2023)) highly vesiculated fall deposits are expected to exist. In Elysium Planitia enormous numbers of rootless cones are found. The edifice are estimated to be composed of vesiculated pyroclast by the investigation of similar edifice at Iceland(Noguchi et al JVGR (2016). These places are potential site for the source materials of fertile soils.
On the surface of Mars fine granular materials such as regolith and dust are widely distributed. The starting question in this presentation is "Is the martian regolith suitable for martian agriculture?" What kind of regolith materials is suitable?, If identified where to obtain? To answer these questions we have conducted a series of simple experiments to evaluate "fertility" of regolith-analog materials.
We used a commercial small CO2 sensor with WiFi/Bluetooth communication ability ( RATOC Systems Inc., ). The sample is mixture of analog of surface regolith and mulch( 2:1,3:1 in wight ratio). They are put into a sealed plastic case and monitor CO2 concentration at 1min. Interval. Tested analog of the regolith is vesiculated ones: Kawagodaira pyroclastic flow deposit, Hachinohe pyroclastic flow deposit, Kanumatuchi (pyroclastic fall deposit of Akagi volcano), Chuseri pyroclastic fall deposit at Towada and non-vesiculated ones: glass sand (commercial name:Zariganinosuna) and glass beads of 0.5mm. In the first several hours all the samples exhibit similar increase in CO2 concentration. In the long term observation quite different behaviors are observed. In Kawagodaira PFlow deposit high concentration about 4000ppm has been maintaied while in Zariganisnosuna
after reaching the maximum the concentration is gradually decreasing in the time scale of several days. This behavior is same as the case of glass beads. Other vesiculated samples exhibit similar behavior except for Kanumatuchi. In vesiculated samples microorganisms could survive and grow while non-vesiculated samples the activity of microorganisms is inhibited. The existence of micropores seems to be a controlling factor. We can conclude vesiculated microporous materials are good candidates for fertile soil. The importance of micropores in the activity of microorganisms has been already pointed out by Or et al(2007) and we could confirm their arguments.
Availability of vesiculated materials on Mars: Several investigations have clarified recent activities of explosive eruptions on Mars by using high resolution imagery. Around these vents in Cerberus Fossae(Moitra et al EPSL 567(2021) )and Arabia Tera(Bates et al Icarus 390 (2023)) highly vesiculated fall deposits are expected to exist. In Elysium Planitia enormous numbers of rootless cones are found. The edifice are estimated to be composed of vesiculated pyroclast by the investigation of similar edifice at Iceland(Noguchi et al JVGR (2016). These places are potential site for the source materials of fertile soils.