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Fig. 1 | Sustainable Earth

Fig. 1

From: From space back to Earth: supporting sustainable development with spaceflight technologies

Fig. 1

An example for a closed loop. Beginning with CO2 and H2O, these can be transformed e.g. via plant growth to O2 and Carbohydrates (i.e. edible bio mass). Consumption, e.g. by the human crew, transforms these via metabolism to CO2 and H2O again, yet also waste (either from the human metabolism or e.g. in the form of non-edible biomass). This waste has to be transformed into its constituents again, resulting in the initial condition. This is a simplified representation. Actual compositions of materials are more complex (e.g. including nitrogen)

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